Acute Tricyclic Antidepressant Poisoning

Complex MONDO:0018547 Pathograph 72 Show in embeddings browser Poisoning

Acute toxicity after excessive exposure to a tricyclic antidepressant, usually through intentional or accidental ingestion. Cardiac sodium-channel inhibition, delayed repolarization, vascular and antimuscarinic effects, and central nervous system toxicity can occur together, with severity varying by drug, dose, absorption and coexposures. Severe poisoning can cause seizures, coma, shock, ventricular dysrhythmias and cardiac arrest. Management requires rapid clinical and ECG assessment, supportive care and sodium bicarbonate for clinically important cardiotoxicity.

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20
Pathophys.
33
Phenotypes
72
Pathograph
2
Genes
15
Medical Actions
3
Differentials
9
Models
8
References
1
Deep Research
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Pathophysiology

20
Systemic Tricyclic Antidepressant Burden
Absorbed parent drug and, for some TCAs, active metabolites produce toxic systemic and tissue exposure. Lipid solubility, extensive protein binding, variable metabolism and delayed gastrointestinal absorption influence the course. The contributions of individual pharmacological targets differ among drugs and patients.
Animal models
Amitriptyline distribution and lipid-infusion pig model Domestic swine perturbs Measures redistribution between plasma and sampled tissues after lipid infusion.
Downstream
Cardiac Fast Sodium Channel Blockade
hERG Potassium Channel Blockade
Vascular Alpha-1 Adrenergic Receptor Blockade
Muscarinic Acetylcholine Receptor Antagonism
Neuronal Norepinephrine Reuptake Inhibition
Histamine H1 Receptor Inhibition
Reduced GABAA Receptor Current Demonstrated for selected drugs, concentrations and receptor subtypes in experimental preparations; the strength of this contribution in clinical poisoning is unresolved.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"TCAs are highly lipid-soluble and extensively protein-bound."
Supports distribution and binding properties.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Toxicity results from both the parent drug and active metabolites."
Corrects a parent-drug-only interpretation of the exposure.
Cardiac Fast Sodium Channel Blockade
Tricyclic exposure inhibits cardiac fast sodium-channel function. Amitriptyline depresses the phase 0 upstroke in isolated Purkinje fibers in a rate-dependent manner. Recovery kinetics differ between drugs; experimental recovery times should not be treated as a single class-wide value or a clinical dosing rule.
cardiac Purkinje fiber cell CL:0002068 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cardiac Purkinje fiber cell, annotated with Purkinje myocyte (CL:0002068). CL:0002068 is a cell type from the Cell Ontology.
SCN5A hgnc:10593 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SCN5A (hgnc:10593). hgnc:10593 is a gene from the HUGO Gene Nomenclature Committee.
cardiac voltage-gated sodium channel activity GO:0086006 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased cardiac voltage-gated sodium channel activity, annotated with voltage-gated sodium channel activity involved in cardiac muscle cell action potential (GO:0086006). GO:0086006 is a molecular function from the Gene Ontology. ↓ DECREASED
Downstream
Slowed Cardiac Phase 0 Depolarization
Reduced Myocardial Contractility Reduced excitability can contribute to myocardial depression, alongside dysrhythmias and other drug effects; this is not a single directly measured channel-to-force step.
Show evidence (3 references)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"The principal mechanism of toxicity is cardiac sodium channel blockade, which increases the duration of the cardiac action potential and refractory period and delays atrioventricular conduction."
Supports cardiac sodium-channel blockade as a major mechanism; the downstream graph separates depolarization and repolarization.
PMID:6092616 SUPPORT DIRECT PRIMARY RESULT In Vitro
"The effects of amitriptyline on phase 0 were rate-dependent."
Shows rate dependence in isolated Purkinje fibers.
PMID:20507243 SUPPORT DIRECT REVIEW SYNTHESIS Other
"Sodium channels have faster recovery times after exposure to lidocaine (1-2 s) and phenytoin (0.71 s), than with some TCAs such as amitriptyline (13.6 s), but not others (e.g., imipramine at 1.6 s)."
The review reports drug-dependent experimental channel-recovery kinetics; this is not a direct clinical comparison.
Slowed His-Purkinje and Myocardial Conduction
Slowed conduction through specialized conducting tissue and working myocardium contributes to QRS widening and conduction block. PR changes and drug-induced Brugada-pattern ECGs can also occur; an acquired Brugada pattern does not by itself diagnose an inherited arrhythmia syndrome.
cardiac conduction GO:0061337 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cardiac conduction (GO:0061337). GO:0061337 is a biological process from the Gene Ontology. ↓ DECREASED
Animal models
Nortriptyline-infusion swine model of severe tricyclic cardiotoxicity Domestic swine recapitulates The model is defined by the conduction defect: animals were dosed until the QRS exceeded 120 ms, and QRS duration is the primary electrocardiographic outcome.
Intraperitoneal amitriptyline rat model of tricyclic cardiotoxicity Rat partially recapitulates QRS duration lengthens significantly in every amitriptyline-treated group, so the conduction defect is reproduced.
Downstream
Ventricular Arrhythmogenesis Heterogeneous conduction can favor reentry; this route does not explain all polymorphic arrhythmias.
Prolonged QRS complex
Atrioventricular block
Right bundle branch block
Show evidence (1 reference)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Electrocardiographic changes include prolongation of the PR, QRS and QT intervals, nonspecific ST segment and T wave changes, atrioventricular block, right axis deviation of the terminal 40 ms vector of the QRS complex in the frontal plane (T 40 ms axis) and the Brugada pattern (downsloping ST..."
Describes the reported ECG spectrum without assigning every interval change to one ion current.
Ventricular Arrhythmogenesis
Conduction abnormalities and, in some cases, disturbed repolarization create susceptibility to ventricular dysrhythmias. Conduction-related monomorphic tachycardia and repolarization-related torsades have different mechanisms; ventricular fibrillation and arrest may complicate severe toxicity.
ventricular cardiomyocyte CL:2000046 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves ventricular cardiomyocyte, annotated with ventricular cardiac muscle cell (CL:2000046). CL:2000046 is a cell type from the Cell Ontology.
Downstream
Ventricular tachycardia
Ventricular fibrillation
Cardiac arrest
Show evidence (1 reference)
PMID:11060957 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Cardiovascular toxicity is classically manifested as ventricular dysrhythmias, hypotension, heart block, bradyarrhythmias, or asystole."
Describes the range of cardiovascular complications, not proof that all are reentrant.
hERG Potassium Channel Blockade
Imipramine and amitriptyline inhibit hERG-mediated potassium current in expression systems. Amitriptyline also reduced IKr in isolated rat atrial myocytes. Voltage and use dependence depend on the drug and assay; these experiments do not directly measure receptor occupancy or current in poisoned patients.
KCNH2 hgnc:6251 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves KCNH2 (hgnc:6251). hgnc:6251 is a gene from the HUGO Gene Nomenclature Committee.
rapid delayed-rectifier potassium channel activity GO:0086008 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased rapid delayed-rectifier potassium channel activity, annotated with voltage-gated potassium channel activity involved in cardiac muscle cell action potential repolarization (GO:0086008). GO:0086008 is a molecular function from the Gene Ontology. ↓ DECREASED
Experimental models
hERG-expressing CHO cells CELL LINE Transiently transfected CHO cells underwent voltage-clamp recording during imipramine or amitriptyline exposure. Current inhibition was reversible; detailed imipramine kinetics suggested both closed- and open-state components without direct structural binding evidence.
hERG-expressing oocytes and isolated rat atrial myocytes OTHER Amitriptyline concentration-, voltage- and use-dependent effects were studied in hERG-expressing Xenopus oocytes; a separate isolated-rat-atrial-cell assay measured native IKr inhibition.
Downstream
Delayed Ventricular Repolarization
Show evidence (3 references)
PMID:10510461 SUPPORT DIRECT PRIMARY RESULT In Vitro
"HERG-encoded potassium channels were inhibited in a reversible manner by both imipramine and amitriptyline."
Demonstrates inhibition in transfected CHO cells, not a patient-level channel assay.
PMID:10742304 SUPPORT DIRECT PRIMARY RESULT In Vitro
"In rat atrial myocytes bathed in 35 degrees C, 5 microM amitriptyline blocked I(Kr) by 55%."
Shows the native-current finding in isolated rat atrial cells.
PMID:10742304 SUPPORT DIRECT PRIMARY RESULT In Vitro
"Block of HERG by amitriptyline was use dependent: exhibiting a much faster block at higher activation frequency."
Use dependence was demonstrated for amitriptyline under the reported expression-system protocol, not for every TCA in vivo.
Slowed Cardiac Phase 0 Depolarization
The amplitude and maximum rate of the fast cardiac action-potential upstroke decrease. This depolarization defect is distinct from the potassium-current-related repolarization branch.
cardiomyocyte CL:0000746 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cardiomyocyte, annotated with cardiac muscle cell (CL:0000746). CL:0000746 is a cell type from the Cell Ontology.
cardiac muscle cell action potential GO:0086001 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal cardiac muscle cell action potential (GO:0086001). GO:0086001 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Experimental models
Isolated cardiac Purkinje fibers exposed to amitriptyline OTHER Amitriptyline-exposed Purkinje fibers were superfused with high sodium, high bicarbonate or high-pH/low-CO2 solutions to separate components of phase 0 recovery.
Downstream
Slowed His-Purkinje and Myocardial Conduction
Show evidence (1 reference)
PMID:6092616 SUPPORT DIRECT PRIMARY RESULT In Vitro
"Amitriptyline significantly depressed action potential amplitude and Vmax without altering resting membrane potential and abbreviated action potential duration at all phases of repolarization."
Measures the phase 0 defect in isolated fibers. Action-potential duration shortened in this preparation, so these results do not support a universal repolarization-prolongation step.
Delayed Ventricular Repolarization
Reduced repolarizing potassium current can delay ventricular repolarization and contribute to QT prolongation. Torsades de pointes is reported but uncommon; QT also includes the depolarization interval, so a prolonged QT in a wide-QRS tracing is not a pure measurement of hERG inhibition.
ventricular membrane repolarization GO:0098915 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased ventricular membrane repolarization, annotated with membrane repolarization during ventricular cardiac muscle cell action potential (GO:0098915). GO:0098915 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Prolonged QT interval
Ventricular Arrhythmogenesis Delayed repolarization can favor triggered polymorphic ventricular arrhythmia; this is distinct from the conduction-related route.
Torsade de pointes
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Cardiac potassium efflux channel inhibition: Slows phase 3 of the cardiac action potential, prolonging the QT interval and increasing the risk of torsades de pointes"
Clinical synthesis supplies the repolarization consequence of potassium-current inhibition.
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Torsade de pointes occurs uncommonly."
Qualifies the clinical arrhythmia consequence.
Reduced Myocardial Contractility
Myocardial depression reduces pump function in severe poisoning. Channel effects and dysrhythmias can contribute, but the cited clinical synthesis does not quantitatively separate these contributions.
ventricular cardiomyocyte CL:2000046 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves ventricular cardiomyocyte, annotated with ventricular cardiac muscle cell (CL:2000046). CL:2000046 is a cell type from the Cell Ontology.
cardiac muscle contraction GO:0060048 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cardiac muscle contraction (GO:0060048). GO:0060048 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Circulatory Failure
Show evidence (1 reference)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade."
Identifies two contributors to hypotension; their relative importance varies.
Vascular Alpha-1 Adrenergic Receptor Blockade
Antagonism of vascular alpha-1 adrenergic signaling reduces vasoconstrictor tone and can contribute to hypotension.
vascular smooth muscle cell CL:0000359 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves vascular smooth muscle cell, annotated with vascular associated smooth muscle cell (CL:0000359). CL:0000359 is a cell type from the Cell Ontology.
alpha1-adrenergic receptor activity GO:0004937 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased alpha1-adrenergic receptor activity (GO:0004937). GO:0004937 is a molecular function from the Gene Ontology. ↓ DECREASED
Downstream
Reduced Systemic Vascular Resistance
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Adrenergic receptor inhibition: Causes vasodilation, hypotension, and reflex tachycardia"
Clinical synthesis links alpha-1 receptor inhibition to loss of vascular tone.
Reduced Systemic Vascular Resistance
Vasodilation reduces systemic vascular resistance and contributes to low arterial pressure, with or without substantial myocardial depression.
vascular associated smooth muscle contraction GO:0014829 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased vascular associated smooth muscle contraction (GO:0014829). GO:0014829 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Circulatory Failure
Show evidence (1 reference)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade."
Identifies two contributors to hypotension; their relative importance varies.
Circulatory Failure
Inadequate circulatory function can reflect myocardial depression, dysrhythmia, vasodilation and volume-related contributions. Severe hypotension may progress to shock or arrest; shock is not necessarily purely cardiogenic.
Animal models
Nortriptyline-infusion swine model of severe tricyclic cardiotoxicity Domestic swine recapitulates The same dosing endpoint includes profound hypotension, and systolic pressure after treatment is the model's other primary outcome.
Amitriptyline-infusion swine model of tricyclic-induced hypotension Domestic swine recapitulates The model is defined by a haemodynamic endpoint and reads out mean arterial pressure and cardiac output continuously.
Downstream
Hypotension
Shock
Cardiac arrest
Systemic Acidaemia Poor tissue perfusion can promote metabolic acidosis; respiratory compromise may contribute separately.
Show evidence (1 reference)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade."
Identifies two contributors to hypotension; their relative importance varies.
Systemic Acidaemia
Metabolic and respiratory acidosis can complicate severe poisoning. Hypoperfusion, inadequate ventilation and seizures can contribute. Lower pH increases the free pharmacologically active drug fraction and can aggravate cardiac sodium-channel toxicity, creating a feedback loop.
Downstream
Increased Free Tricyclic Antidepressant Fraction
Cardiac Fast Sodium Channel Blockade
Acidosis
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Respiratory or metabolic acidosis increases the free, pharmacologically active TCA fraction, enhancing toxicity."
Supports the pH-dependent availability mechanism without asserting complete channel binding by one ionization state.
Muscarinic Acetylcholine Receptor Antagonism
Tricyclic drugs inhibit muscarinic receptor signaling, producing peripheral and central antimuscarinic manifestations. This toxidrome overlaps other poisonings and neither confirms TCA exposure nor excludes severe cardiotoxicity when absent.
muscarinic acetylcholine receptor activity GO:0016907 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased muscarinic acetylcholine receptor activity, annotated with G protein-coupled acetylcholine receptor activity (GO:0016907). GO:0016907 is a molecular function from the Gene Ontology. ↓ DECREASED
Downstream
Sinus tachycardia
Mydriasis
Urinary retention
Dry skin
Delirium
Xerostomia
Blurred vision
Reduced Gastrointestinal Motility
Hyperthermia
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium"
Clinical synthesis identifies the antimuscarinic branch.
PMID:2996040 SUPPORT DIRECT PRIMARY RESULT In Vitro
"Half maximal inhibition of acetylcholine receptor binding occurred for amitriptylinoxide at 18 mumol/l (amitriptyline: 0.32 mumol/l)."
The binding assay reports an amitriptyline inhibitory concentration; it does not establish identical potency for the entire class.
Neuronal Norepinephrine Reuptake Inhibition
Inhibition of norepinephrine reuptake contributes to autonomic stimulation, including sinus tachycardia. TCAs also affect serotonin transport, but the cited cardiovascular causal link is specifically to norepinephrine uptake.
SLC6A2 hgnc:11048 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SLC6A2 (hgnc:11048). hgnc:11048 is a gene from the HUGO Gene Nomenclature Committee.
norepinephrine reuptake transporter activity GO:0005334 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased norepinephrine reuptake transporter activity, annotated with norepinephrine:sodium symporter activity (GO:0005334). GO:0005334 is a molecular function from the Gene Ontology. ↓ DECREASED
Downstream
Sinus tachycardia Increased noradrenergic signaling contributes to sinus-rate acceleration.
Hyperthermia The review refers to biogenic amines broadly; the specific noradrenergic contribution is inferred and need not be sufficient.
Show evidence (1 reference)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Sinus tachycardia is the most common arrhythmia due to anticholinergic activity and inhibition of norepinephrine uptake by tricyclic antidepressants"
Identifies norepinephrine reuptake inhibition as a contribution to sinus tachycardia.
Central Nervous System Depression
Toxic exposure can cause drowsiness, reduced consciousness and coma, with impaired ventilation or airway protection in severe cases. Clinical severity is variable; coma is not an inevitable response to every toxic ingestion.
Downstream
Drowsiness
Coma
Respiratory depression
Apnea Severe depressed ventilatory drive can progress to apnea, although the guideline does not isolate this route experimentally.
Show evidence (2 references)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Level of consciousness at presentation is the most sensitive clinical predictor of serious complications."
The review identifies depressed consciousness as a clinical risk marker.
PMID:42582545 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Clinical presentations included altered mental status (46.7%) and drowsiness (29.3%)."
The 75-person tertiary-center series reports altered consciousness and drowsiness; inclusion/exclusion criteria and pretreatment limit generalization.
Central Neuronal Hyperexcitability
TCA poisoning can lower seizure threshold through multiple pharmacological and physiological influences. Experimental GABAA effects offer one possible route. A selected intubated/comatose case-control study associated post-admission seizures with death, but this is not a validated universal prognostic rule or evidence that QRS duration measures brain drug exposure.
Downstream
Seizure
Status epilepticus
Systemic Acidaemia Sustained convulsive activity can contribute to metabolic acidosis.
Agitation The clinical finding is observed; its specific molecular route is unresolved.
Hyperreflexia The clinical finding is observed; its specific molecular route is unresolved.
Ankle clonus The clinical finding is observed; its specific molecular route is unresolved.
Tremor The clinical association is documented, with the specific molecular route unresolved.
Myoclonus The clinical association is documented, with the specific molecular route unresolved.
Show evidence (2 references)
PMID:7618783 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Seizures occurred in 16 patients (20%) and ventricular arrhythmias in 5 (6%)."
Seizures occurred in 16 of 79 patients in the selected prospective poisoning cohort.
PMID:21740136 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The only prognostic indicator of death in such patients is seizure after hospital presentation."
This association applies to the study’s intubated, comatose case-control population.
Increased Free Tricyclic Antidepressant Fraction
Acidosis can increase the unbound pharmacologically active fraction of circulating TCA. A change in free fraction is distinct from an increase in total body drug amount.
Downstream
Cardiac Fast Sodium Channel Blockade Greater unbound exposure can increase delivery to and inhibition of cardiac sodium channels.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Respiratory or metabolic acidosis increases the free, pharmacologically active TCA fraction, enhancing toxicity."
Supports the pH-dependent availability mechanism without asserting complete channel binding by one ionization state.
Reduced Gastrointestinal Motility
Antimuscarinic effects slow gastrointestinal motility, causing decreased bowel sounds and potentially ileus, while delaying absorption of ingested drug.
Downstream
Ileus
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"TCA poisoning produces anticholinergic effects that slow gastrointestinal motility, delaying absorption and peak drug concentrations."
Supports the gut-motility event.
Histamine H1 Receptor Inhibition
Histamine H1 receptor blockade contributes to TCA sedation. Profound coma is a clinical toxic effect with multiple possible contributions, not a receptor-specific readout.
HRH1 hgnc:5182 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves HRH1 (hgnc:5182). hgnc:5182 is a gene from the HUGO Gene Nomenclature Committee.
histamine H1 receptor activity GO:0004969 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased histamine H1 receptor activity, annotated with histamine receptor activity (GO:0004969). GO:0004969 is a molecular function from the Gene Ontology. ↓ DECREASED
Downstream
Central Nervous System Depression Reduced central histaminergic arousal is one contribution to depressed consciousness.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK425165/ SUPPORT DIRECT BACKGROUND Other
"Given that the tricyclics can also block different receptors (H1 histamine,"
The pharmacogenetic chapter identifies H1 receptor blockade among TCA actions.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Histamine receptor inhibition: Produces sedation, altered mental status, and increased seizure risk"
The synthesis describes a histamine-receptor contribution to sedation; it does not establish that this explains all coma.
Reduced GABAA Receptor Current
Selected TCAs reduce GABA-elicited chloride current or uptake in experimental systems. Imipramine and nortriptyline inhibited recombinant α5β3γ2 receptors but had no significant effect on the tested α1β3γ2 subtype at 100 μM. Rat cortical assays also showed inhibition by amitriptyline. These findings support a possible contribution to neuroexcitation, not a proven single cause of clinical seizures.
GABA-A receptor activity GO:0004890 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased GABA-A receptor activity (GO:0004890). GO:0004890 is a molecular function from the Gene Ontology. ↓ DECREASED
Experimental models
Rat cortical GABA-stimulated chloride-uptake preparations OTHER Rat cerebral cortical vesicles showed reduced GABA-stimulated chloride uptake during selected antidepressant exposure. A later Schild analysis included amitriptyline and did not support pure competitive GABA antagonism.
Recombinant GABAA subtype assays in Xenopus oocytes OTHER Two-electrode voltage clamp compared drug effects in recombinant receptor combinations. At 100 μM, imipramine and nortriptyline inhibited α5β3γ2 currents but lacked significant inhibition at the tested α1β3γ2 subtype. Mutational effects suggest a putative allosteric pocket, not a structurally proven binding pose.
Downstream
Central Neuronal Hyperexcitability Reduced inhibitory signaling may contribute to seizure susceptibility, but the experiments do not establish its necessity or quantitative contribution in human overdose.
Show evidence (4 references)
PMID:35088415 SUPPORT DIRECT PRIMARY RESULT In Vitro
"All of them diminished GABA‐elicited currents in α5β3γ2 receptors"
Includes imipramine and nortriptyline in recombinant oocytes; this does not demonstrate clinical seizure mediation.
PMID:35088415 SUPPORT DIRECT PRIMARY RESULT In Vitro
"The chlorpromazine‐ levomepromazine‐ imipramine‐ nortriptyline group had no significant effects on the α1β3γ2 receptors at 100 μM."
The negative comparator constrains generalization of the subtype-specific current inhibition.
PMID:2456440 SUPPORT DIRECT PRIMARY RESULT In Vitro
"Using the method of GABA-stimulated 36Cl-uptake by rat cerebral cortical vesicles, we show that some antidepressant drugs (imipramine, amitryptyline, and mianserine) can inhibit the GABA-receptor chloride uptake"
Demonstrates inhibition in rat cortical vesicles; the source spells the drug names this way.
+ 1 more reference
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Acute Tricyclic Antidepressant Poisoning Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

33
Cardiovascular 11
Prolonged QRS complex HP:0006677 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Prolonged QRS complex (HP:0006677). HP:0006677 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:4022081 SUPPORT INDIRECT PRIMARY RESULT Human Clinical
"Seizures occurred at any QRS duration of 0.10 second or longer (P less than 0.05), but ventricular arrhythmias were seen only with a QRS duration of 0.16 second or longer (P less than 0.0005)."
Reports cohort-specific ECG associations, not absolute risk cutoffs or exposure levels.
Prolonged QT interval HP:0001657 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Prolonged QT interval (HP:0001657). HP:0001657 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Cardiac potassium efflux channel inhibition: Slows phase 3 of the cardiac action potential, prolonging the QT interval and increasing the risk of torsades de pointes"
Clinical synthesis supplies the repolarization consequence of potassium-current inhibition.
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Torsade de pointes occurs uncommonly."
Qualifies the arrhythmia consequence.
Atrioventricular block HP:0001678 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Atrioventricular block (HP:0001678). HP:0001678 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"bradyarrhythmias (due to atrioventricular block) and tachyarrhythmias (supraventricular and ventricular) may occur"
Names atrioventricular block as the cause of the bradyarrhythmias seen in this poisoning.
Ventricular tachycardia HP:0004756 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ventricular tachycardia (HP:0004756). HP:0004756 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:3784839 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Ventricular tachycardia (monomorphic) is a consequence of impaired myocardial depolarisation and impulse conduction."
Supports the clinical rhythm and its conduction-related mechanism; the aggregate ventricular-arrhythmia rate is not a VT-specific frequency.
Ventricular fibrillation HP:0001663 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ventricular fibrillation (HP:0001663). HP:0001663 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:21740136 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Ten cases and none of the controls had advanced ECG changes (ventricular fibrillation, torsades des pointes, or asystole)."
Fibrillation was included among advanced ECG abnormalities in the selected study; 10 refers to the aggregate ECG category, not fibrillation alone.
Cardiac arrest HP:0001695 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cardiac arrest (HP:0001695). HP:0001695 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33655968 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"At 200 minutes after ingestion, he experienced a TCA-induced cardiac arrest."
Documents cardiac arrest attributed to the poisoning, with the interval from ingestion.
Hypotension HP:0002615 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypotension (HP:0002615). HP:0002615 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade."
States both contributions to the hypotension.
Sinus tachycardia HP:0011703 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Sinus tachycardia (HP:0011703). HP:0011703 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:10452441 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Aside from the sinus tachycardia due principally to anticholinergic effects, TCA-toxic changes seen on the ECG are attributable primarily to the sodium channel blockade caused by these agents."
Separates the sinus tachycardia, which is anticholinergic, from the rest of the electrocardiographic picture, which is not.
PMID:3784839 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Sinus tachycardia with QRS prolongation may be difficult to distinguish from ventricular tachycardia."
Supports the bedside-confusion claim made in this phenotype's description and in the Ventricular tachycardia one.
Right bundle branch block HP:0011710 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Right bundle branch block, annotated with Bundle branch block (HP:0011710). HP:0011710 is a phenotype from the Human Phenotype Ontology.
Coarse binding: no hpo term
Ontology gap: Live HPO search in September 2026 found complete and incomplete right bundle branch block, but no unqualified right-sided term. The review does not specify completeness, so the parent bundle-branch-block term preserves the supported scope.
Show evidence (1 reference)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Electrocardiographic changes include prolongation of the PR, QRS and QT intervals, nonspecific ST segment and T wave changes, atrioventricular block, right axis deviation of the terminal 40 ms vector of the QRS complex in the frontal plane (T 40 ms axis) and the Brugada pattern (downsloping ST..."
Describes the Brugada pattern of this poisoning as right bundle branch block with right precordial ST elevation.
Shock HP:0031273 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Shock (HP:0031273). HP:0031273 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33655968 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"all cases went into refractory shock and cardiac arrest despite adequate fluid resuscitation and sodium bicarbonate administration"
Describes the selected published rescue cases, without a disease-wide rate or a pure cardiogenic classification.
Torsade de pointes HP:0001664 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Torsade de pointes (HP:0001664). HP:0001664 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Torsade de pointes occurs uncommonly."
The qualitative source does not justify a numerical frequency band.
Digestive 1
Ileus HP:0002595 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ileus (HP:0002595). HP:0002595 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Other signs of TCA poisoning include palpita tions, tachycardia, hyperten- sion, ileus, tremors, myoclonu s, confusion, delirium, and lethargy."
This is the guideline’s acute-poisoning clinical list; spacing in the PDF extraction is preserved.
Eye 2
Mydriasis HP:0011499 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Mydriasis (HP:0011499). HP:0011499 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:3537621 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness."
Lists dilated pupils among the commonest clinical features.
Blurred vision HP:0000622 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Blurred vision (HP:0000622). HP:0000622 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:3537621 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness."
Lists blurred vision among the commonest clinical features.
Genitourinary 1
Urinary retention HP:0000016 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Urinary retention (HP:0000016). HP:0000016 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium"
Clinical synthesis identifies the antimuscarinic branch.
Head and Neck 1
Xerostomia HP:0000217 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Xerostomia (HP:0000217). HP:0000217 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:3537621 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness."
Lists dry mouth among the commonest clinical features.
Immune 1
Aspiration pneumonia HP:0011951 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Aspiration pneumonia (HP:0011951). HP:0011951 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Pulmonary complica- tions (e.g., respirat ory depression, sudde n apnea, aspiration pneumonia, adult-type respirat ory distress syndrome, and pulmonary edema) can be life threatening."
The guideline explicitly lists severe pulmonary complications; this does not establish their incidence or one shared mechanism.
Integument 1
Dry skin HP:0000958 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dry skin (HP:0000958). HP:0000958 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium"
Clinical synthesis identifies the antimuscarinic branch.
Limbs 1
Ankle clonus HP:0011448 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ankle clonus (HP:0011448). HP:0011448 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Neurologic examination may demonstrate CNS depression, delirium, ankle clonus, hyperreflexia, or seizures."
Specifically names ankle clonus.
Metabolism 3
Acidosis HP:0001941 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Acidosis (HP:0001941). HP:0001941 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Respiratory or metabolic acidosis increases the free, pharmacologically active TCA fraction, enhancing toxicity."
Supports the pH-dependent availability mechanism without asserting complete channel binding by one ionization state.
Hyperthermia Fever HP:0001945 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hyperthermia, annotated with Fever (HP:0001945). HP:0001945 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Physical examination may reveal tachycardia, hypotension, and, in severe cases, hyperthermia."
Documents hyperthermia in severe toxicity without a disease-wide frequency.
Pulmonary edema HP:0100598 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Pulmonary edema (HP:0100598). HP:0100598 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Pulmonary complica- tions (e.g., respirat ory depression, sudde n apnea, aspiration pneumonia, adult-type respirat ory distress syndrome, and pulmonary edema) can be life threatening."
The guideline explicitly lists severe pulmonary complications; this does not establish their incidence or one shared mechanism.
Nervous System 9
Coma HP:0001259 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Coma (HP:0001259). HP:0001259 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:3537621 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"In severe poisoning, there may be coma, convulsions, respiratory depression, hypotension and a wide range of electrocardiographic (ECG) abnormalities."
The review includes coma among severe manifestations.
Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (3 references)
PMID:7618783 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Seizures occurred in 16 patients (20%) and ventricular arrhythmias in 5 (6%)."
The denominator is 79 selected patients; no pooled disease frequency is inferred.
PMID:21740136 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The only prognostic indicator of death in such patients is seizure after hospital presentation."
Restricted to the study’s intubated/comatose case-control population.
PMID:7904010 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The odds ratio for seizures with dothiepin versus other TCAs was 6.7 (95% Cl 2.2-20.7) unadjusted and 7.1 (2.2-23.2) after adjustment for sex, age, and ingested dose."
Reports a drug-specific association after adjustment, not proof that dose or all confounding was eliminated.
Status epilepticus HP:0002133 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Status epilepticus (HP:0002133). HP:0002133 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:33655968 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"His seizure stopped after intravenous administration of diazepam, and he was intubated because of his comatose status and generalized status epilepticus."
Documents generalized status epilepticus, and its response to a benzodiazepine, in an amitriptyline overdose.
Delirium HP:0031258 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Delirium (HP:0031258). HP:0031258 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium"
Clinical synthesis identifies the antimuscarinic branch.
Agitation HP:0000713 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Agitation (HP:0000713). HP:0000713 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Initial symptoms commonly include CNS manifestations, such as agitation, confusion, delirium, drowsiness, and seizures, as well as autonomic findings, including dry mouth and urinary retention."
The chapter explicitly includes agitation.
Drowsiness HP:0002329 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Drowsiness (HP:0002329). HP:0002329 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:3537621 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness."
Explicitly includes drowsiness.
Hyperreflexia HP:0001347 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hyperreflexia (HP:0001347). HP:0001347 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Neurologic examination may demonstrate CNS depression, delirium, ankle clonus, hyperreflexia, or seizures."
Lists this neurological finding without a frequency estimate.
Tremor HP:0001337 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Tremor (HP:0001337). HP:0001337 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Other signs of TCA poisoning include palpita tions, tachycardia, hyperten- sion, ileus, tremors, myoclonu s, confusion, delirium, and lethargy."
This is the guideline’s acute-poisoning clinical list; spacing in the PDF extraction is preserved.
Myoclonus HP:0001336 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Myoclonus (HP:0001336). HP:0001336 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Other signs of TCA poisoning include palpita tions, tachycardia, hyperten- sion, ileus, tremors, myoclonu s, confusion, delirium, and lethargy."
This is the guideline’s acute-poisoning clinical list; spacing in the PDF extraction is preserved.
Respiratory 2
Respiratory depression Hypoventilation HP:0002791 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Respiratory depression, annotated with Hypoventilation (HP:0002791). HP:0002791 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:3537621 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"In severe poisoning, there may be coma, convulsions, respiratory depression, hypotension and a wide range of electrocardiographic (ECG) abnormalities."
Directly names respiratory depression.
Apnea HP:0002104 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Apnea (HP:0002104). HP:0002104 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Pulmonary complica- tions (e.g., respirat ory depression, sudde n apnea, aspiration pneumonia, adult-type respirat ory distress syndrome, and pulmonary edema) can be life threatening."
The guideline explicitly lists severe pulmonary complications; this does not establish their incidence or one shared mechanism.
🧬

Genetic Associations

2
CYP2D6 (CYP2D6 activity affects therapeutic TCA exposure; poor metabolizers can have higher plasma concentrations at usual doses. This pharmacokinetic modifier is not a genetic cause of poisoning, and the cited guidance does not validate CYP2D6 genotype as a predictor of acute-overdose outcome.)
Gene: CYP2D6 hgnc:2625 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is CYP2D6 (hgnc:2625). hgnc:2625 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: MODIFIER
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK425165/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"The FDA-approved drug label for amitriptyline states that CYP2D6 PM have higher than expected plasma concentrations of tricyclic antidepressants when given usual doses."
The claim concerns therapeutic-dose plasma exposure, not acute-poisoning prognosis.
CYP2C19 (CYP2C19 contributes to demethylation of amitriptyline to active nortriptyline. Altered activity can change the parent-to-metabolite balance; this is not equivalent to removing all pharmacological activity. Therapeutic pharmacogenetic recommendations do not establish acute-overdose outcome prediction.)
Gene: CYP2C19 hgnc:2621 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is CYP2C19 (hgnc:2621). hgnc:2621 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: MODIFIER
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK425165/ SUPPORT DIRECT REVIEW SYNTHESIS Other
"Metabolism by CYP2C19 results in active metabolites, including nortriptyline, which is also a tricyclic antidepressant"
Directly identifies the active metabolite.
💊

Medical Actions

15
Sodium Bicarbonate
Category: Therapeutic Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: sodium bicarbonate NCIT:C29457 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses sodium bicarbonate (NCIT:C29457). NCIT:C29457 is a therapeutic agent from the NCI Thesaurus.
Platform: Small molecule
Core therapy for clinically important TCA cardiotoxicity, including hemodynamic instability, QRS widening and dysrhythmias. Sodium loading and alkalinization can improve sodium-current-dependent conduction and reduce active free drug. Serial ECG, pH and electrolytes guide treatment; excessive alkalemia, sodium loading and hypokalemia are relevant limits. The optimal endpoint and maintenance strategy are not settled by the experimental comparisons.
Mechanism Target:
INHIBITS Cardiac Fast Sodium Channel Blockade — Improves the functional conduction consequences of blockade; molecular displacement and complete reversal are not established by clinical ECG improvement.
Show evidence (1 reference)
PMID:6092616 SUPPORT DIRECT PRIMARY RESULT In Vitro
"The results suggest that the beneficial effects of NaHCO3 are related to a reversal of drug effects on phase 0 characteristics and that this effect is due both to alkalinization and to increases in extracellular Na concentration."
The isolated-fiber experiments support contributions from both sodium and pH; they do not establish complete reversal or one dominant clinical mechanism.
INHIBITS Systemic Acidaemia
Show evidence (1 reference)
PMID:3784839 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Hypertonic sodium bicarbonate is of particular benefit in patients who are acidotic, since acidosis aggravates cardiac toxicity."
Supports correction of acidemia as part of care.
INHIBITS Increased Free Tricyclic Antidepressant Fraction
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Therapeutic effects include restoration of inward cardiac sodium current and reduction of the free TCA fraction."
The chapter describes reduction of the active free fraction.
Show evidence (3 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Sodium bicarbonate is indicated for hemodynamic instability, acidemia, seizures, or QRS prolongation greater than 100 milliseconds."
The contemporary chapter gives clinical indications; ECG values are interpreted alongside symptoms and hemodynamics.
PMID:6092616 SUPPORT DIRECT PRIMARY RESULT In Vitro
"The results suggest that the beneficial effects of NaHCO3 are related to a reversal of drug effects on phase 0 characteristics and that this effect is due both to alkalinization and to increases in extracellular Na concentration."
The isolated-fiber experiments support contributions from both sodium and pH; they do not establish complete reversal or one dominant clinical mechanism.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Hypokalemia commonly develops during sodium bicarbonate therapy"
Supports monitoring for a treatment-related electrolyte complication.
Hypertonic Saline
Category: Therapeutic Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: hypertonic saline NCIT:C60814 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses hypertonic saline (NCIT:C60814). NCIT:C60814 is a therapeutic agent from the NCI Thesaurus.
Platform: Small molecule
Additional sodium loading has been studied experimentally and may be considered by toxicology specialists in refractory sodium-channel toxicity when further alkalinization is limited. Animal results do not demonstrate superiority to bicarbonate in human poisoning. Sodium and acid-base monitoring are necessary.
Mechanism Target:
MODULATES Slowed Cardiac Phase 0 Depolarization — Experimental sodium loading can improve depressed phase 0 characteristics; clinical rescue efficacy is less certain.
Show evidence (1 reference)
PMID:6092616 SUPPORT DIRECT PRIMARY RESULT In Vitro
"The results suggest that the beneficial effects of NaHCO3 are related to a reversal of drug effects on phase 0 characteristics and that this effect is due both to alkalinization and to increases in extracellular Na concentration."
The isolated-fiber experiments support contributions from both sodium and pH; they do not establish complete reversal or one dominant clinical mechanism.
Show evidence (2 references)
PMID:20507243 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Primary treatment strategies include sodium bicarbonate, hypertonic saline, and correction of any conditions that may aggravate this toxicity such as acidosis, hyperthermia, and hypotension."
The review includes hypertonic saline among treatment strategies; it does not rank it above bicarbonate.
PMID:9737495 SUPPORT DIRECT PRIMARY RESULT Model Organism
"Mean QRS duration 10 minutes after treatment was 144+/-38 ms in the control group, 80+/-14 ms in the HTS group, 105+/-38 ms in the NaHCO3 group, and 125+/-46 ms in the HV group (P<.05)."
The swine study used different sodium doses in the saline and bicarbonate arms, limiting mechanistic comparison.
Activated Charcoal
Category: Therapeutic Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: activated charcoal CHEBI:91090 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses activated charcoal, annotated with charcoal (CHEBI:91090). CHEBI:91090 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Other
Selected gastrointestinal decontamination can adsorb unabsorbed TCA. Use requires an appropriate airway and assessment of aspiration or gastrointestinal contraindications; it must not delay transport or resuscitation. A trial comparing three active charcoal/decontamination regimens had no untreated control, so no difference between arms does not establish absence of benefit.
Mechanism Target:
MODULATES Systemic Tricyclic Antidepressant Burden — Adsorption of drug remaining in the gastrointestinal tract can reduce further absorption; it does not remove drug already distributed in tissues.
Show evidence (1 reference)
PMID:11060957 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Activated charcoal binds tricyclic antidepressants."
Supports luminal adsorption; reduced exposure and outcome benefit depend on timing and selection.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Gastrointestinal decontamination with activated charcoal should only be performed in patients with a protected airway who are not vomiting."
Defines selection and airway safety rather than recommending routine administration.
url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Prehospital activated charcoal administration, if available, should only be carried out by health professionals and only if no contraindications are present. Do not delay transportation in order to administer activated charcoal (Grades B/D)."
The 2007 prehospital guideline gives a conditional professional-use recommendation.
Benzodiazepine Anticonvulsant Therapy
Category: Therapeutic Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: diazepam NCIT:C28982 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses diazepam (NCIT:C28982). NCIT:C28982 is a therapeutic agent from the NCI Thesaurus.
Platform: Small molecule
Benzodiazepines are first-line therapy for TCA-associated convulsions. Refractory seizures may require phenobarbital or propofol with airway protection. Seizure control also limits secondary acidosis; prognosis from selected severe cohorts should not be treated as a universal rule.
Mechanism Target:
INHIBITS Central Neuronal Hyperexcitability
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"TCA-induced seizures generally respond to benzodiazepines or other GABA agonists."
Supports benzodiazepines for toxin-induced seizures.
INHIBITS Status epilepticus
Show evidence (1 reference)
PMID:33655968 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"His seizure stopped after intravenous administration of diazepam, and he was intubated because of his comatose status and generalized status epilepticus."
A severe case documents diazepam use and seizure termination; it is not a comparative efficacy study.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"TCA-induced seizures generally respond to benzodiazepines or other GABA agonists."
Supports benzodiazepines for toxin-induced seizures.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Refractory seizures may require phenobarbital or propofol, typically after endotracheal intubation for airway protection."
Provides the escalation context.
Intravenous Fluid Resuscitation
Category: Therapeutic Action: Fluid TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Fluid Therapy (NCIT:C116537). NCIT:C116537 is a clinical intervention from the NCI Thesaurus. NCIT:C116537
Platform: Other
Intravenous fluids support circulation when hypotension has a volume-responsive component, alongside bicarbonate and other indicated resuscitation. Persistent instability requires escalation; the source does not establish a mandatory fluids-first delay or routine central venous pressure monitoring.
Mechanism Target:
MODULATES Circulatory Failure
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Initial management of hypotension includes intravenous fluids and sodium bicarbonate."
Supports both early interventions without a rigid sequence that delays bicarbonate.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Initial management of hypotension includes intravenous fluids and sodium bicarbonate."
Supports both early interventions without a rigid sequence that delays bicarbonate.
Vasopressor Support
Category: Therapeutic Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: norepinephrine bitartrate NCIT:C48646 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses norepinephrine bitartrate (NCIT:C48646). NCIT:C48646 is a therapeutic agent from the NCI Thesaurus. epinephrine CHEBI:33568 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses epinephrine, annotated with adrenaline (CHEBI:33568). CHEBI:33568 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Vasopressors, commonly norepinephrine, may be needed for persistent hypotension despite initial resuscitation. Support is individualized with bicarbonate and other care; animal comparisons of catecholamines do not establish the best human regimen.
Mechanism Target:
INHIBITS Reduced Systemic Vascular Resistance — Alpha-adrenergic support can restore vascular tone; no receptor-occupancy competition was measured in the cited clinical source.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Persistent hypotension may require &#x003b1;-adrenergic vasopressors, such as norepinephrine."
The current chapter supports norepinephrine for persistent hypotension.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Persistent hypotension may require &#x003b1;-adrenergic vasopressors, such as norepinephrine."
The current chapter supports norepinephrine for persistent hypotension.
Lidocaine
Category: Therapeutic Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: lidocaine CHEBI:6456 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses lidocaine (CHEBI:6456). CHEBI:6456 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Class Ib antiarrhythmic rescue may be considered for life-threatening TCA ventricular dysrhythmias refractory to bicarbonate, with specialist input. Experimental channel-recovery kinetics provide a rationale but vary by TCA and do not prove a universal displacement mechanism.
Mechanism Target:
MODULATES Ventricular Arrhythmogenesis — Intended to suppress refractory ventricular dysrhythmias; an established molecular reversal of TCA occupancy is not claimed.
Show evidence (1 reference)
PMID:20507243 SUPPORT DIRECT REVIEW SYNTHESIS Other
"Sodium channels have faster recovery times after exposure to lidocaine (1-2 s) and phenytoin (0.71 s), than with some TCAs such as amitriptyline (13.6 s), but not others (e.g., imipramine at 1.6 s)."
Different experimental recovery kinetics support a possible rationale; they do not directly demonstrate clinical arrhythmia prevention.
Show evidence (1 reference)
PMID:20507243 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"We recommend the use of lidocaine in cases in which cardiotoxicity (arrhythmias, hypotension) is refractory to treatment with sodium bicarbonate or hypertonic saline"
The review supports possible use; current guidance distinguishes limited-evidence class Ib rescue from routine use.
Intravenous Lipid Emulsion
Category: Therapeutic Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Platform: Other
A potential rescue option for severe lipophilic-TCA toxicity after standard therapies fail, supported by low-certainty guidance and case reports. Animal experiments show drug redistribution without consistent hemodynamic benefit. Lower brain concentration or a lower tissue-to-plasma ratio does not mean total body TCA burden has fallen.
Mechanism Target:
MODULATES Circulatory Failure — A proposed rescue of hemodynamic failure, with uncertain efficacy; not an assertion that total systemic drug burden is eliminated.
Show evidence (1 reference)
PMID:22244291 SUPPORT INDIRECT PRIMARY RESULT Human Clinical
"We report a case of dothiepin (tricyclic antidepressant) overdose causing refractory cardiovascular collapse, which seemed to be successfully reversed with lipid-emulsion therapy"
The case supplies limited clinical support for rescue of cardiovascular collapse.
Show evidence (5 references)
PMID:27608281 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"if other therapies fail, we recommend ILE for bupivacaine toxicity and we suggest using ILE for toxicity due to other LAs, amitriptyline, and bupropion"
The recommendation is for rescue after failure of other treatments.
PMID:27608281 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"All recommendations were based on very low quality of evidence."
Qualifies certainty.
PMID:23639060 SUPPORT DIRECT PRIMARY RESULT Model Organism
"In spite of the entrapment, there was no difference in haemodynamics between the groups."
This protocol showed no hemodynamic advantage despite redistribution; it is a limitation, not a vote against all possible rescue settings.
+ 2 more references
Veno-Arterial Extracorporeal Membrane Oxygenation
Category: Therapeutic Action: veno-arterial extracorporeal membrane oxygenationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is veno-arterial extracorporeal membrane oxygenation, annotated with Extracorporeal Membrane Oxygenation (NCIT:C171507). NCIT:C171507 is a clinical intervention from the NCI Thesaurus. Ontology label: Extracorporeal Membrane Oxygenation NCIT:C171507
Platform: Device
Extracorporeal circulatory support may be considered for refractory shock or cardiac arrest despite conventional resuscitation. It can provide a bridge through potentially reversible poisoning, but recovery time and neurological outcome vary. Published rescue cases with concurrent treatments do not establish isolated efficacy.
Mechanism Target:
BYPASSES Circulatory Failure — Provides mechanical circulatory support while toxicity and organ dysfunction are treated; it does not directly remove sodium-channel blockade.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Rare cases may require advanced support with extracorporeal membrane oxygenation."
Supports rescue-level mechanical support.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Rare cases may require advanced support with extracorporeal membrane oxygenation."
Supports rescue-level mechanical support.
PMID:33655968 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Twenty seven hours after starting the pump, the patient was weaned off the VA-ECMO."
Documents the time course of one case, not a universal duration.
Mechanical Ventilation
Category: Therapeutic Action: mechanical ventilationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is mechanical ventilation (NCIT:C70909). NCIT:C70909 is a clinical intervention from the NCI Thesaurus. Ontology label: Mechanical Ventilation NCIT:C70909
Platform: Device
Airway protection and ventilatory support are used for inadequate ventilation, loss of airway protection or treatment of refractory seizures. Avoiding respiratory acidosis is important during intubation and subsequent care. Controlled hyperventilation may be an adjunct in already ventilated life-threatening sodium-channel poisoning; this does not establish a routine prophylactic-intubation indication. Neuromuscular paralysis does not itself terminate cortical seizure activity.
Mechanism Target:
BYPASSES Respiratory depression — Supports gas exchange when respiratory drive or airway protection is inadequate.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Management of TCA poisoning begins with prompt stabilization of the airway, breathing, and circulation."
Supports airway and ventilatory assessment as initial resuscitation.
Show evidence (3 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Management of TCA poisoning begins with prompt stabilization of the airway, breathing, and circulation."
Supports airway and ventilatory assessment as initial resuscitation.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Careful monitoring of serum pH is essential before endotracheal intubation because peri-intubation respiratory acidosis may occur."
Identifies the peri-intubation acid-base risk.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Refractory seizures may require phenobarbital or propofol, typically after endotracheal intubation for airway protection."
Supports airway protection in treatment escalation.
Avoidance of potentially harmful antidotes and antiarrhythmics
Category: Therapeutic
Physostigmine and flumazenil are generally avoided in TCA toxicity. Class IA, IC and III antiarrhythmics can aggravate toxicity; this caution does not encompass all rhythm treatment, since selected class Ib rescue and torsades-specific care have different roles. Antimuscarinic delirium or hyperthermia should not be described as harmless.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Physostigmine, class IA, IC, and III antiarrhythmic agents, and flumazenil are relatively contraindicated in TCA toxicity."
The current synthesis explicitly records the caution.
Toxicology consultation and serial monitoring
Category: Monitoring
Early poison-center or medical-toxicology consultation informs triage and management. Serial clinical assessment, ECG, pH and electrolytes guide treatment and escalation; asymptomatic observation decisions depend on reliable exposure history and clinical context.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Consultation with a medical toxicologist or regional poison center is recommended for all cases of known or suspected TCA poisoning."
Supports consultation for suspected as well as confirmed poisoning.
Psychiatric assessment after intentional overdose
Category: Diagnostic
After medical stabilization, assess suicide risk and arrange appropriate psychiatric care following intentional ingestion.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Psychiatric consultation should be obtained after medical stabilization in cases of intentional overdose to assess suicide risk and guide further treatment."
Specifies both timing and purpose.
Medication safety and storage counseling
Category: Counseling / Informational Action: CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Counseling (NCIT:C61547). NCIT:C61547 is a clinical intervention from the NCI Thesaurus. NCIT:C61547
Counsel on prescribed dosing, medication errors and safe storage out of the reach of children.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Preventive counseling should emphasize adherence to prescribed dosing, avoidance of unsupervised dose adjustments, and safe medication storage out of the reach of children."
Supports exposure prevention counseling.
Torsades-directed resuscitation
Category: Therapeutic Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: magnesium sulfate CHEBI:32599 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses magnesium sulfate (CHEBI:32599). CHEBI:32599 is a therapeutic agent from Chemical Entities of Biological Interest.
Documented torsades de pointes requires rhythm-specific resuscitation, including magnesium where indicated, alongside correction of toxic and electrolyte contributors. A prolonged QT alone is not the same event as torsades.
Mechanism Target:
MODULATES Torsade de pointes
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Patients who develop torsades de pointes should be managed according to ACLS protocols, and additional magnesium may be administered during cardiopulmonary resuscitation when feasible."
Provides torsades-specific management.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Patients who develop torsades de pointes should be managed according to ACLS protocols, and additional magnesium may be administered during cardiopulmonary resuscitation when feasible."
Provides torsades-specific management.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"A typical initial dose is 2 g of magnesium sulfate."
Identifies the agent; no fixed-dose instruction is inferred for every age or scenario.
🌍

Environmental Factors

1
Ingestion of a tricyclic antidepressant in overdose
exposure to tricyclic antidepressants ECTO:2000024 Environmental Conditions, Treatments and Exposures Ontology (ECTO) Relation: this environmental factor is this exposure This environmental factor is exposure to tricyclic antidepressants (ECTO:2000024). ECTO:2000024 is an exposure from the Environmental Conditions, Treatments and Exposures Ontology.
Relative toxicity indices compare selected population data and do not yield a patient-specific fatality probability. Exposure is acquired; inherited pharmacokinetic variation is a modifier rather than a requirement.
Excessive TCA ingestion can be intentional, accidental or related to medication error. Different drugs have different observed overdose toxicity, and dose estimates, coingestants and patient factors limit individual prediction.
Show evidence (3 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Intentional self-harm is the leading cause of TCA overdose in adults."
Describes adult exposure context.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"In children, accidental or exploratory ingestions can cause significant toxicity because of the narrow therapeutic index of these drugs."
Includes the pediatric accidental-exposure setting.
PMID:20435959 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Within the TCAs, compared with amitriptyline both dosulepin (relative toxicity index 2.7) and doxepin (2.6) were more toxic."
The observational comparison found higher relative toxicity indices for dosulepin and doxepin than amitriptyline; the two drugs differ from the pair highlighted in the separate cardiovascular review.
Mechanism Target:
TRIGGERS Systemic Tricyclic Antidepressant Burden — The ingestion is the route by which the systemic drug burden is established. Everything else in the entry is downstream of it.
Show evidence (1 reference)
PMID:17453872 SUPPORT DIRECT BACKGROUND Human Clinical
"A review of U.S. poison center data for 2004 showed over 12,000 exposures to tricyclic antidepressants (TCAs)."
Establishes ingestion exposure as the event poison-control systems record and triage, which is the exposure this link names.
🔬

Diagnosis

3
Exposure history and clinical assessment
Establish the drug, estimated amount, formulation, timing, coingestants and relevant cardiac or seizure history. An antimuscarinic toxidrome is suggestive but is shared with other poisons and can be incomplete.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"When TCA toxicity is suspected, the history should include the specific drug ingested, estimated dose, formulation, time of ingestion, and any coingestants, including prescription, over-the-counter, and herbal products."
Specifies the necessary exposure history.
PMID:10452441 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"the presence or absence of features of the TCA toxidrome are not sufficient to detect or exclude toxicity from this class of drugs"
Neither the presence nor absence of the toxidrome is a definitive diagnostic test.
Serial 12-lead electrocardiography
Obtain an early ECG and follow QRS duration, rhythm, QT and the terminal aVR vector with the clinical course. Historical QRS and aVR associations aid risk assessment but cannot independently rule in or rule out serious toxicity. ECG findings are not unique to TCAs.
Show evidence (5 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"An ECG should be obtained early in the evaluation of suspected TCA overdose."
Supports early ECG assessment.
PMID:4022081 SUPPORT INDIRECT PRIMARY RESULT Human Clinical
"Seizures occurred at any QRS duration of 0.10 second or longer (P less than 0.05), but ventricular arrhythmias were seen only with a QRS duration of 0.16 second or longer (P less than 0.0005)."
The thresholds are observed cohort associations, not deterministic boundaries.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"An R/S ratio of 0.7 or greater in lead aVR or an R wave greater than 3 mm in lead aVR is strongly associated with both seizures and arrhythmias."
The chapter summarizes aVR risk associations; these are not definitive diagnostic cutoffs.
+ 2 more references
Laboratory assessment and coingestant evaluation
Assess glucose, acid-base status and electrolytes, and evaluate possible acetaminophen, salicylate or other coingestants. Serum TCA measurements can support an uncertain exposure history but do not reliably quantify severity or replace clinical monitoring.
Show evidence (3 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Standard laboratory evaluation should include assessment for potential coingestants, such as acetaminophen and aspirin."
Supports coingestant testing.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Serum TCA concentrations do not reliably correlate with toxicity severity and are not always clinically available, although measurement may help confirm an unknown overdose when clinical findings suggest TCA ingestion."
Separates exposure confirmation from severity prediction.
PMID:3537621 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"There must be regular monitoring for hypoxia, acidosis and hypokalaemia"
Supports repeated assessment of acidosis, hypoxia and potassium.
📈

Progression

2
Early presentation
Clinical manifestations often develop within two hours, but antimuscarinic slowing of gastrointestinal transit and coingestants can delay absorption. Initial antimuscarinic or neurological findings can precede abrupt severe cardiotoxicity.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"The manifestations of toxicity usually become apparent within 2 hours of ingestion."
Supports the usual early onset without making it a universal exclusion window.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"TCA poisoning produces anticholinergic effects that slow gastrointestinal motility, delaying absorption and peak drug concentrations."
Identifies delayed absorption as a toxicokinetic contributor.
Severe toxicity and recovery
Seizures, depressed consciousness, dysrhythmias and hemodynamic instability require hospital care and repeated assessment. Toxicity often lasts 24–48 hours but varies with exposure; severe or prolonged courses occur. An asymptomatic observation window must be interpreted in the context of ECG findings, exposure history and poison-center assessment, particularly after self-harm.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Toxicity usually lasts 24 to 48 hours but is highly dose-dependent."
Provides a typical course rather than a promised recovery time.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Patients with signs of toxicity generally require hospital admission until sustained clinical improvement occurs."
Supports admission for clinically apparent toxicity.
⚖️

Clinical Burden

High
Potentially fatal acute poisoning with rapid deterioration in severe cases. Historical UK observational comparisons found greater relative overdose toxicity for TCAs than for several newer antidepressant classes, with substantial variation within the TCA class. These comparisons and selected hospital cohorts do not provide a universal mortality percentage or population incidence.
Show evidence (2 references)
PMID:20435959 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Case fatality rate ratios showed greater toxicity for TCAs (13.8, 95% CI 13.0-14.7) than the SNRI venlafaxine (2.5, 95% CI 2.0-3.1) and the NaSSA mirtazapine (1.9, 95% CI 1.1-2.9), both of which had greater toxicity than the SSRIs (0.5, 95% CI 0.4-0.7)."
The published figures are comparative rate ratios, not percentages. Mortality, prescribing and nonfatal-overdose data came from different geographic source populations, with limitations including dose and coingestant information.
PMID:16390222 SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Life-threatening arrhythmias and death due to tricyclic antidepressant poisoning usually occurs within 24 hours of ingestion."
The review locates most life-threatening cardiac events within the first day; this does not guarantee that all toxicity ends at 24 hours.
🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from Acute Tricyclic Antidepressant Poisoning:

Other antimuscarinic drug poisoning
Overlapping Features Antihistamines, antipsychotics, cyclobenzaprine and tropane alkaloids can produce overlapping antimuscarinic findings. Exposure history and the complete clinical course are essential; several alternative agents can also cause cardiac toxicity.
Distinguishing Features
  • A toxidrome alone cannot identify the drug; establish the exposure and assess coingestants.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Initial manifestations often resemble those of an anticholinergic toxidrome caused by antihistamines, such as diphenhydramine and chlorpheniramine"
The chapter describes overlapping clinical presentations.
Other cardiotoxic drug poisoning
Overlapping Features Class I antiarrhythmics and other cardiotoxic agents can mimic the ECG and circulatory findings of TCA poisoning.
Distinguishing Features
  • Medication and exposure history help distinguish the cause; QRS widening is not specific to TCAs.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Cardiotoxic agents can produce ECG abnormalities that mimic those of TCA poisoning."
Explicitly identifies the ECG differential.
Hypoglycemia and other metabolic encephalopathies
Overlapping Features Metabolic disorders can cause altered mental status or seizures and may coexist with poisoning.
Distinguishing Features
  • Check glucose and relevant metabolic studies while stabilizing the patient.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/ SUPPORT DIRECT REVIEW SYNTHESIS Human Clinical
"Metabolic disorders may likewise cause altered mental status. Potential etiologies include hypoglycemia, hyperglycemia, hyponatremia, hypernatremia, hepatic encephalopathy, uremic encephalopathy, and thyroid storm."
Supports the metabolic differential and glucose assessment.
🧫

Experimental Models

5
Isolated cardiac Purkinje fibers exposed to amitriptyline OTHER
Amitriptyline-exposed Purkinje fibers were superfused with high sodium, high bicarbonate or high-pH/low-CO2 solutions to separate components of phase 0 recovery.
Publication
PMID:6092616
Pathograph links
Slowed Cardiac Phase 0 Depolarization recapitulates fidelity: moderate Amitriptyline-exposed Purkinje fibers were superfused with high sodium, high bicarbonate or high-pH/low-CO2 solutions to separate components of phase 0 recovery.
Limitations: An isolated electrophysiological preparation lacks systemic pharmacokinetics and clinical outcomes; action-potential duration shortened in this experiment.
Show evidence (2 references)
PMID:6092616 SUPPORT DIRECT PRIMARY RESULT In Vitro
"Amitriptyline significantly depressed action potential amplitude and Vmax without altering resting membrane potential and abbreviated action potential duration at all phases of repolarization."
Measures the phase 0 defect in isolated fibers. Action-potential duration shortened in this preparation, so these results do not support a universal repolarization-prolongation step.
+ 1 more reference
hERG-expressing CHO cells CELL_LINE
Transiently transfected CHO cells underwent voltage-clamp recording during imipramine or amitriptyline exposure. Current inhibition was reversible; detailed imipramine kinetics suggested both closed- and open-state components without direct structural binding evidence.
Publication
PMID:10510461
Pathograph links
hERG Potassium Channel Blockade recapitulates fidelity: moderate Transiently transfected CHO cells underwent voltage-clamp recording during imipramine or amitriptyline exposure. Current inhibition was reversible; detailed imipramine kinetics suggested both closed- and open-state components without direct structural binding evidence.
Limitations: Cloned-channel inhibition does not reproduce a whole cardiac action potential or measure clinical free-drug concentrations. Drug, voltage protocol and expression-system conditions affect kinetics.
Show evidence (1 reference)
PMID:10510461 SUPPORT DIRECT PRIMARY RESULT In Vitro
"HERG-encoded potassium channels were inhibited in a reversible manner by both imipramine and amitriptyline."
Demonstrates inhibition in transfected CHO cells, not a patient-level channel assay.
hERG-expressing oocytes and isolated rat atrial myocytes OTHER
Amitriptyline concentration-, voltage- and use-dependent effects were studied in hERG-expressing Xenopus oocytes; a separate isolated-rat-atrial-cell assay measured native IKr inhibition.
Publication
PMID:10742304
Pathograph links
hERG Potassium Channel Blockade recapitulates fidelity: moderate Amitriptyline concentration-, voltage- and use-dependent effects were studied in hERG-expressing Xenopus oocytes; a separate isolated-rat-atrial-cell assay measured native IKr inhibition.
Limitations: The two experimental systems differ from human ventricular tissue, and the measurements do not establish clinical frequency or severity of torsades.
Show evidence (1 reference)
PMID:10742304 SUPPORT DIRECT PRIMARY RESULT In Vitro
"In rat atrial myocytes bathed in 35 degrees C, 5 microM amitriptyline blocked I(Kr) by 55%."
Documents the native IKr assay, distinct from the oocyte expression system.
Rat cortical GABA-stimulated chloride-uptake preparations OTHER
Rat cerebral cortical vesicles showed reduced GABA-stimulated chloride uptake during selected antidepressant exposure. A later Schild analysis included amitriptyline and did not support pure competitive GABA antagonism.
Publication
PMID:2456440
Pathograph links
Reduced GABAA Receptor Current recapitulates fidelity: moderate Rat cerebral cortical vesicles showed reduced GABA-stimulated chloride uptake during selected antidepressant exposure. A later Schild analysis included amitriptyline and did not support pure competitive GABA antagonism.
Limitations: Ex vivo uptake and binding analyses do not demonstrate that this mechanism is necessary or sufficient for seizures in poisoned humans.
Show evidence (2 references)
PMID:2456440 SUPPORT DIRECT PRIMARY RESULT In Vitro
"Using the method of GABA-stimulated 36Cl-uptake by rat cerebral cortical vesicles, we show that some antidepressant drugs (imipramine, amitryptyline, and mianserine) can inhibit the GABA-receptor chloride uptake"
Demonstrates inhibition in rat cortical vesicles; the source spells the drug names this way.
+ 1 more reference
Recombinant GABAA subtype assays in Xenopus oocytes OTHER
Two-electrode voltage clamp compared drug effects in recombinant receptor combinations. At 100 μM, imipramine and nortriptyline inhibited α5β3γ2 currents but lacked significant inhibition at the tested α1β3γ2 subtype. Mutational effects suggest a putative allosteric pocket, not a structurally proven binding pose.
Publication
PMID:35088415
Pathograph links
Reduced GABAA Receptor Current recapitulates fidelity: moderate Two-electrode voltage clamp compared drug effects in recombinant receptor combinations. At 100 μM, imipramine and nortriptyline inhibited α5β3γ2 currents but lacked significant inhibition at the tested α1β3γ2 subtype. Mutational effects suggest a putative allosteric pocket, not a structurally proven binding pose.
Limitations: The study focused largely on antipsychotic pharmacology, used recombinant receptors and did not assay TCA-poisoned patients or seizures. Antipsychotic orthosteric-binding results cannot be assigned to TCAs.
Show evidence (2 references)
PMID:35088415 SUPPORT DIRECT PRIMARY RESULT In Vitro
"All of them diminished GABA‐elicited currents in α5β3γ2 receptors"
Includes imipramine and nortriptyline in recombinant oocytes; this does not demonstrate clinical seizure mediation.
+ 1 more reference
🐁

Animal Models

4
Nortriptyline-infusion swine model of severe tricyclic cardiotoxicity
Twenty-four swine received intravenous nortriptyline to QRS >120 ms and systolic pressure ≤50 mmHg, then were randomized to saline, bicarbonate, hyperventilation or control. Hypertonic saline improved QRS and pressure most at ten minutes under this protocol, but provided 15 mEq/kg sodium compared with 3 mEq/kg in the bicarbonate arm; this was not an equisodium comparison.
Species
Domestic swine
Publication
PMID:9737495
Pathograph links
Slowed His-Purkinje and Myocardial Conduction recapitulates fidelity: moderate observes: organism The model is defined by the conduction defect: animals were dosed until the QRS exceeded 120 ms, and QRS duration is the primary electrocardiographic outcome.
Limitations: Intravenous exposure in anesthetized animals, short follow-up and unequal sodium doses limit translation and separation of sodium versus alkalinization effects.
Show evidence (1 reference)
PMID:9737495 SUPPORT DIRECT PRIMARY RESULT Model Organism
"Twenty-four mixed-breed, domestic swine of either sex were given an intravenous infusion of nortriptyline (NT) until development of both a QRS duration longer than 120 ms and a systolic blood pressure (SBP) less than or equal to 50 mm Hg."
States the dosing endpoint, which is the conduction defect this link names.
Circulatory Failure recapitulates fidelity: moderate observes: organism The same dosing endpoint includes profound hypotension, and systolic pressure after treatment is the model's other primary outcome.
Limitations: Intravenous exposure in anesthetized animals, short follow-up and unequal sodium doses limit translation and separation of sodium versus alkalinization effects.
Show evidence (1 reference)
PMID:9737495 SUPPORT DIRECT PRIMARY RESULT Model Organism
"The mean SBP 10 minutes after treatment was 54+/-18 mm Hg in the control group, 134+/-21 mm Hg in the HTS group, 85+/-19 mm Hg in the NaHCO3 group, and 60+/-12 mm Hg in the HV group (P<.05)."
Reports the blood-pressure recovery across arms, which is the circulatory endpoint this link names.
Amitriptyline-infusion swine model of tricyclic-induced hypotension
Twenty-four female swine with amitriptyline-induced severe hypotension were randomized to lipid emulsion or bicarbonate. ILE did not improve hypotension compared with bicarbonate in this pilot. Survival was poor, and the small protocol-specific comparison does not exclude benefit in every human rescue setting.
Species
Domestic swine
Publication
PMID:25377397
Pathograph links
Circulatory Failure recapitulates fidelity: moderate observes: organism The model is defined by a haemodynamic endpoint and reads out mean arterial pressure and cardiac output continuously.
Limitations: Severe intravenous intoxication in anesthetized swine, small groups and high mortality limit power and generalization to clinical rescue.
Show evidence (1 reference)
PMID:25377397 SUPPORT DIRECT PRIMARY RESULT Model Organism
"24 female Sus scrofa swine weighing 45 to 55 kg were infused with amitriptyline at 0.5 mg/kg/min until the MAP reached 60% of baseline values"
States the haemodynamic endpoint that defines the model.
Show evidence (1 reference)
PMID:25377397 SUPPORT DIRECT PRIMARY RESULT Model Organism
"24 female Sus scrofa swine weighing 45 to 55 kg were infused with amitriptyline at 0.5 mg/kg/min until the MAP reached 60% of baseline values"
States the species, dose rate and haemodynamic endpoint that define the model, including the 60%-of-baseline figure quoted in its description.
Intraperitoneal amitriptyline rat model of tricyclic cardiotoxicity
Thirty-six female Sprague-Dawley rats were divided into six groups: three received intraperitoneal amitriptyline alone or with simultaneous sodium bicarbonate or hypertonic saline, and three served as saline/bicarbonate/control comparison groups. ECG changes and time to the study death endpoint were followed for 60 minutes. This tests prophylaxis during experimental intoxication, not delayed rescue after oral human overdose.
Species
Rat
Publication
PMID:25939777
Pathograph links
Slowed His-Purkinje and Myocardial Conduction partially recapitulates fidelity: moderate observes: organism QRS duration lengthens significantly in every amitriptyline-treated group, so the conduction defect is reproduced.
Limitations: Intraperitoneal exposure, concomitant prophylactic therapy, anesthetic coexposures, 60-minute follow-up and a heart-rate/asystole death endpoint limit translation. Blood pH was not measured, and sodium sampling differed between early deaths and survivors.
Show evidence (1 reference)
PMID:25939777 SUPPORT DIRECT PRIMARY RESULT Model Organism
"the amitriptyline-administered groups (groups 1, 2 and 3) showed a statistically significant increase in the QRS duration"
Reports the conduction defect reproduced in the model.
Show evidence (1 reference)
PMID:25939777 SUPPORT DIRECT PRIMARY RESULT Model Organism
"Amitriptyline was administered at a dose 50 mg/kg i.p. to induce toxicity."
States the dosing route and amount that define the model.
Amitriptyline distribution and lipid-infusion pig model
Twenty anesthetized pigs received intravenous amitriptyline, followed after tissue distribution by randomized lipid emulsion or Ringer acetate. Lipid increased plasma total drug and reduced brain concentration by 25%; the lower heart/plasma ratio does not establish lower absolute cardiac concentration. No severe arrhythmias occurred and hemodynamics did not differ between groups.
Species
Domestic swine
Publication
PMID:23639060
Pathograph links
Systemic Tricyclic Antidepressant Burden perturbs fidelity: moderate observes: organism Measures redistribution between plasma and sampled tissues after lipid infusion.
Limitations: Total concentration and tissue/plasma ratios do not measure unbound drug at channel sites or total-body elimination; this model did not reproduce severe arrhythmia.
Show evidence (2 references)
PMID:23639060 SUPPORT DIRECT PRIMARY RESULT Model Organism
"Lipid emulsion reduced brain amitriptyline concentration by 25% (p = 0.038) and amitriptyline concentration ratios brain/arterial plasma (p = 0.016) and heart/arterial plasma (p = 0.011)."
Reports distinct concentration and ratio endpoints.
+ 1 more reference
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name: Acute Tricyclic Antidepressant Poisoning
creation_date: '2026-09-20T21:00:00Z'
description: Acute toxicity after excessive exposure to a tricyclic antidepressant, usually through intentional or accidental ingestion. Cardiac sodium-channel inhibition, delayed repolarization, vascular and antimuscarinic effects, and central nervous system toxicity can occur together, with severity varying by drug, dose, absorption and coexposures. Severe poisoning can cause seizures, coma, shock, ventricular dysrhythmias and cardiac arrest. Management requires rapid clinical and ECG assessment, supportive care and sodium bicarbonate for clinically important cardiotoxicity.
categories:
- Toxic Exposure Disorder
- Treatment Toxicity
category: Complex
parents:
- Poisoning
synonyms:
- TCA overdose
- tricyclic antidepressant overdose
- tricyclic antidepressant toxicity
disease_term:
  preferred_term: acute tricyclic antidepressant poisoning
  term:
    id: MONDO:0018547
    label: acute tricyclic antidepressant poisoning
clinical_burden:
  burden_level: HIGH
  rationale: Potentially fatal acute poisoning with rapid deterioration in severe cases. Historical UK observational comparisons found greater relative overdose toxicity for TCAs than for several newer antidepressant classes, with substantial variation within the TCA class. These comparisons and selected hospital cohorts do not provide a universal mortality percentage or population incidence.
  evidence:
  - reference: PMID:20435959
    reference_title: 'Toxicity of antidepressants: rates of suicide relative to prescribing and non-fatal overdose.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: Case fatality rate ratios showed greater toxicity for TCAs (13.8, 95% CI 13.0-14.7) than the SNRI venlafaxine (2.5, 95% CI 2.0-3.1) and the NaSSA mirtazapine (1.9, 95% CI 1.1-2.9), both of which had greater toxicity than the SSRIs (0.5, 95% CI 0.4-0.7).
    explanation: The published figures are comparative rate ratios, not percentages. Mortality, prescribing and nonfatal-overdose data came from different geographic source populations, with limitations including dose and coingestant information.
    quote_role: PRIMARY_RESULT
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Life-threatening arrhythmias and death due to tricyclic antidepressant poisoning usually occurs within 24 hours of ingestion.
    explanation: The review locates most life-threatening cardiac events within the first day; this does not guarantee that all toxicity ends at 24 hours.
pathophysiology:
- name: Systemic Tricyclic Antidepressant Burden
  description: Absorbed parent drug and, for some TCAs, active metabolites produce toxic systemic and tissue exposure. Lipid solubility, extensive protein binding, variable metabolism and delayed gastrointestinal absorption influence the course. The contributions of individual pharmacological targets differ among drugs and patients.
  biological_scale: ORGANISM
  chemical_entities:
  - preferred_term: amitriptyline
    term:
      id: CHEBI:2666
      label: amitriptyline
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: TCAs are highly lipid-soluble and extensively protein-bound.
    explanation: Supports distribution and binding properties.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Toxicity results from both the parent drug and active metabolites.
    explanation: Corrects a parent-drug-only interpretation of the exposure.
  downstream:
  - target: Cardiac Fast Sodium Channel Blockade
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16390222
      reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The principal mechanism of toxicity is cardiac sodium channel blockade, which increases the duration of the cardiac action potential and refractory period and delays atrioventricular conduction.
      explanation: Supports cardiac sodium-channel blockade as a major mechanism; the downstream graph separates depolarization and repolarization.
  - target: hERG Potassium Channel Blockade
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:10510461
      reference_title: Inhibition of the current of heterologously expressed HERG potassium channels by imipramine and amitriptyline.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: HERG-encoded potassium channels were inhibited in a reversible manner by both imipramine and amitriptyline.
      explanation: Demonstrates inhibition in transfected CHO cells, not a patient-level channel assay.
  - target: Vascular Alpha-1 Adrenergic Receptor Blockade
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Adrenergic receptor inhibition: Causes vasodilation, hypotension, and reflex tachycardia'
      explanation: Clinical synthesis links alpha-1 receptor inhibition to loss of vascular tone.
  - target: Muscarinic Acetylcholine Receptor Antagonism
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
      explanation: Clinical synthesis identifies the antimuscarinic branch.
  - target: Neuronal Norepinephrine Reuptake Inhibition
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16390222
      reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Sinus tachycardia is the most common arrhythmia due to anticholinergic activity and inhibition of norepinephrine uptake by tricyclic antidepressants
      explanation: Identifies norepinephrine reuptake inhibition as a contribution to sinus tachycardia.
  - target: Histamine H1 Receptor Inhibition
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Histamine receptor inhibition: Produces sedation, altered mental status, and increased seizure risk'
      explanation: The synthesis describes a histamine-receptor contribution to sedation; it does not establish that this explains all coma.
  - target: Reduced GABAA Receptor Current
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:35088415
      reference_title: Tricyclic antipsychotics and antidepressants can inhibit α5-containing GABA(A) receptors by two distinct mechanisms.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: All of them diminished GABA‐elicited currents in α5β3γ2 receptors
      explanation: Includes imipramine and nortriptyline in recombinant oocytes; this does not demonstrate clinical seizure mediation.
    description: Demonstrated for selected drugs, concentrations and receptor subtypes in experimental preparations; the strength of this contribution in clinical poisoning is unresolved.
- name: Cardiac Fast Sodium Channel Blockade
  conforms_to: xenobiotic_cardiac_channel_perturbation#Xenobiotic Cardiac Ion-Channel Perturbation
  description: Tricyclic exposure inhibits cardiac fast sodium-channel function. Amitriptyline depresses the phase 0 upstroke in isolated Purkinje fibers in a rate-dependent manner. Recovery kinetics differ between drugs; experimental recovery times should not be treated as a single class-wide value or a clinical dosing rule.
  biological_scale: MOLECULAR
  genes:
  - preferred_term: SCN5A
    term:
      id: hgnc:10593
      label: SCN5A
  molecular_functions:
  - preferred_term: cardiac voltage-gated sodium channel activity
    modifier: DECREASED
    term:
      id: GO:0086006
      label: voltage-gated sodium channel activity involved in cardiac muscle cell action potential
  cell_types:
  - preferred_term: cardiac Purkinje fiber cell
    term:
      id: CL:0002068
      label: Purkinje myocyte
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The principal mechanism of toxicity is cardiac sodium channel blockade, which increases the duration of the cardiac action potential and refractory period and delays atrioventricular conduction.
    explanation: Supports cardiac sodium-channel blockade as a major mechanism; the downstream graph separates depolarization and repolarization.
  - reference: PMID:6092616
    reference_title: Mechanism of reversal of toxic effects of amitriptyline on cardiac Purkinje fibers by sodium bicarbonate.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    snippet: The effects of amitriptyline on phase 0 were rate-dependent.
    explanation: Shows rate dependence in isolated Purkinje fibers.
    quote_role: PRIMARY_RESULT
  - reference: PMID:20507243
    reference_title: What is the role of lidocaine or phenytoin in tricyclic antidepressant-induced cardiotoxicity?
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Sodium channels have faster recovery times after exposure to lidocaine (1-2 s) and phenytoin (0.71 s), than with some TCAs such as amitriptyline (13.6 s), but not others (e.g., imipramine at 1.6 s).
    explanation: The review reports drug-dependent experimental channel-recovery kinetics; this is not a direct clinical comparison.
  downstream:
  - target: Slowed Cardiac Phase 0 Depolarization
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:6092616
      reference_title: Mechanism of reversal of toxic effects of amitriptyline on cardiac Purkinje fibers by sodium bicarbonate.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: Amitriptyline significantly depressed action potential amplitude and Vmax without altering resting membrane potential and abbreviated action potential duration at all phases of repolarization.
      explanation: Measures the phase 0 defect in isolated fibers. Action-potential duration shortened in this preparation, so these results do not support a universal repolarization-prolongation step.
  - target: Reduced Myocardial Contractility
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:25939777
      reference_title: Can empirical hypertonic saline or sodium bicarbonate treatment prevent the development of cardiotoxicity during serious amitriptyline poisoning? Experimental research.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: BACKGROUND
      snippet: Blockage of cardiac sodium and potassium channels may result in cardiac conduction delay, dysrhythmia and hypotension due to myocardial depression.
      explanation: Background synthesis links channel blockade to myocardial depression; the intervening excitation–contraction effects were not isolated by this rat study.
    description: Reduced excitability can contribute to myocardial depression, alongside dysrhythmias and other drug effects; this is not a single directly measured channel-to-force step.
- name: Slowed His-Purkinje and Myocardial Conduction
  description: Slowed conduction through specialized conducting tissue and working myocardium contributes to QRS widening and conduction block. PR changes and drug-induced Brugada-pattern ECGs can also occur; an acquired Brugada pattern does not by itself diagnose an inherited arrhythmia syndrome.
  biological_scale: TISSUE
  biological_processes:
  - preferred_term: cardiac conduction
    modifier: DECREASED
    term:
      id: GO:0061337
      label: cardiac conduction
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Electrocardiographic changes include prolongation of the PR, QRS and QT intervals, nonspecific ST segment and T wave changes, atrioventricular block, right axis deviation of the terminal 40 ms vector of the QRS complex in the frontal plane (T 40 ms axis) and the Brugada pattern (downsloping ST segment elevation in leads V1-V3 in association with right bundle branch block).
    explanation: Describes the reported ECG spectrum without assigning every interval change to one ion current.
  downstream:
  - target: Ventricular Arrhythmogenesis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:3784839
      reference_title: Tricyclic antidepressant poisoning. Management of arrhythmias.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Ventricular tachycardia (monomorphic) is a consequence of impaired myocardial depolarisation and impulse conduction.
      explanation: Supports a conduction-related ventricular-arrhythmia branch.
    description: Heterogeneous conduction can favor reentry; this route does not explain all polymorphic arrhythmias.
  - target: Prolonged QRS complex
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Cardiac sodium channel inhibition: Slows phase 0 of the cardiac action potential, prolonging the QRS interval and increasing the risk of hypotension and dysrhythmias'
      explanation: Links depolarization/conduction slowing with QRS widening.
  - target: Atrioventricular block
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16390222
      reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: bradyarrhythmias (due to atrioventricular block) and tachyarrhythmias (supraventricular and ventricular) may occur
      explanation: Documents conduction block in the clinical spectrum.
  - target: Right bundle branch block
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16390222
      reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Electrocardiographic changes include prolongation of the PR, QRS and QT intervals, nonspecific ST segment and T wave changes, atrioventricular block, right axis deviation of the terminal 40 ms vector of the QRS complex in the frontal plane (T 40 ms axis) and the Brugada pattern (downsloping ST segment elevation in leads V1-V3 in association with right bundle branch block).
      explanation: The review describes right bundle branch block in the Brugada-pattern ECG, without specifying complete block.
- name: Ventricular Arrhythmogenesis
  description: Conduction abnormalities and, in some cases, disturbed repolarization create susceptibility to ventricular dysrhythmias. Conduction-related monomorphic tachycardia and repolarization-related torsades have different mechanisms; ventricular fibrillation and arrest may complicate severe toxicity.
  biological_scale: TISSUE
  cell_types:
  - preferred_term: ventricular cardiomyocyte
    term:
      id: CL:2000046
      label: ventricular cardiac muscle cell
  evidence:
  - reference: PMID:11060957
    reference_title: Tricyclic antidepressant poisoning.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Cardiovascular toxicity is classically manifested as ventricular dysrhythmias, hypotension, heart block, bradyarrhythmias, or asystole.
    explanation: Describes the range of cardiovascular complications, not proof that all are reentrant.
  downstream:
  - target: Ventricular tachycardia
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:3784839
      reference_title: Tricyclic antidepressant poisoning. Management of arrhythmias.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Ventricular tachycardia (monomorphic) is a consequence of impaired myocardial depolarisation and impulse conduction.
      explanation: Supports monomorphic ventricular tachycardia associated with impaired conduction.
  - target: Ventricular fibrillation
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:21740136
      reference_title: Can death unrelated to secondary causes be predicted in intubated comatose tricyclic antidepressant-poisoned patients?
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: Ten cases and none of the controls had advanced ECG changes (ventricular fibrillation, torsades des pointes, or asystole).
      explanation: Documents fibrillation among severe ECG changes in a selected intubated/comatose case-control cohort.
      quote_role: PRIMARY_RESULT
  - target: Cardiac arrest
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33655968
      reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: At 200 minutes after ingestion, he experienced a TCA-induced cardiac arrest.
      explanation: A severe case developed ventricular tachycardia and cardiac arrest; this does not establish one universal arrest mechanism.
      quote_role: PRIMARY_RESULT
- name: hERG Potassium Channel Blockade
  conforms_to: xenobiotic_cardiac_channel_perturbation#Xenobiotic Cardiac Ion-Channel Perturbation
  description: Imipramine and amitriptyline inhibit hERG-mediated potassium current in expression systems. Amitriptyline also reduced IKr in isolated rat atrial myocytes. Voltage and use dependence depend on the drug and assay; these experiments do not directly measure receptor occupancy or current in poisoned patients.
  biological_scale: MOLECULAR
  genes:
  - preferred_term: KCNH2
    term:
      id: hgnc:6251
      label: KCNH2
  molecular_functions:
  - preferred_term: rapid delayed-rectifier potassium channel activity
    modifier: DECREASED
    term:
      id: GO:0086008
      label: voltage-gated potassium channel activity involved in cardiac muscle cell action potential repolarization
  evidence:
  - reference: PMID:10510461
    reference_title: Inhibition of the current of heterologously expressed HERG potassium channels by imipramine and amitriptyline.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: HERG-encoded potassium channels were inhibited in a reversible manner by both imipramine and amitriptyline.
    explanation: Demonstrates inhibition in transfected CHO cells, not a patient-level channel assay.
  - reference: PMID:10742304
    reference_title: Blockade of the HERG human cardiac K(+) channel by the antidepressant drug amitriptyline.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    snippet: In rat atrial myocytes bathed in 35 degrees C, 5 microM amitriptyline blocked I(Kr) by 55%.
    explanation: Shows the native-current finding in isolated rat atrial cells.
    quote_role: PRIMARY_RESULT
  - reference: PMID:10742304
    reference_title: Blockade of the HERG human cardiac K(+) channel by the antidepressant drug amitriptyline.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    snippet: 'Block of HERG by amitriptyline was use dependent: exhibiting a much faster block at higher activation frequency.'
    explanation: Use dependence was demonstrated for amitriptyline under the reported expression-system protocol, not for every TCA in vivo.
    quote_role: PRIMARY_RESULT
  downstream:
  - target: Delayed Ventricular Repolarization
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Cardiac potassium efflux channel inhibition: Slows phase 3 of the cardiac action potential, prolonging the QT interval and increasing the risk of torsades de pointes'
      explanation: Clinical synthesis supplies the repolarization consequence of potassium-current inhibition.
- name: Slowed Cardiac Phase 0 Depolarization
  conforms_to: xenobiotic_cardiac_channel_perturbation#Altered Cardiac Action Potential
  description: The amplitude and maximum rate of the fast cardiac action-potential upstroke decrease. This depolarization defect is distinct from the potassium-current-related repolarization branch.
  biological_scale: CELLULAR
  biological_processes:
  - preferred_term: cardiac muscle cell action potential
    modifier: ABNORMAL
    term:
      id: GO:0086001
      label: cardiac muscle cell action potential
  cell_types:
  - preferred_term: cardiomyocyte
    term:
      id: CL:0000746
      label: cardiac muscle cell
  downstream:
  - target: Slowed His-Purkinje and Myocardial Conduction
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:3784839
      reference_title: Tricyclic antidepressant poisoning. Management of arrhythmias.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Slowing of phase 0 depolarisation of the action potential results in slowing of conduction through the His-Purkinje system and myocardium.
      explanation: States the causal depolarization-to-conduction relationship.
    - reference: PMID:6092616
      reference_title: Mechanism of reversal of toxic effects of amitriptyline on cardiac Purkinje fibers by sodium bicarbonate.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: Effects on phase 0 were accompanied by a depression of conduction velocity.
      explanation: Measures both changes in the same exposed fibers.
  evidence:
  - reference: PMID:6092616
    reference_title: Mechanism of reversal of toxic effects of amitriptyline on cardiac Purkinje fibers by sodium bicarbonate.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: Amitriptyline significantly depressed action potential amplitude and Vmax without altering resting membrane potential and abbreviated action potential duration at all phases of repolarization.
    explanation: Measures the phase 0 defect in isolated fibers. Action-potential duration shortened in this preparation, so these results do not support a universal repolarization-prolongation step.
- name: Delayed Ventricular Repolarization
  description: Reduced repolarizing potassium current can delay ventricular repolarization and contribute to QT prolongation. Torsades de pointes is reported but uncommon; QT also includes the depolarization interval, so a prolonged QT in a wide-QRS tracing is not a pure measurement of hERG inhibition.
  biological_scale: TISSUE
  biological_processes:
  - preferred_term: ventricular membrane repolarization
    modifier: DECREASED
    term:
      id: GO:0098915
      label: membrane repolarization during ventricular cardiac muscle cell action potential
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: 'Cardiac potassium efflux channel inhibition: Slows phase 3 of the cardiac action potential, prolonging the QT interval and increasing the risk of torsades de pointes'
    explanation: Clinical synthesis supplies the repolarization consequence of potassium-current inhibition.
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Torsade de pointes occurs uncommonly.
    explanation: Qualifies the clinical arrhythmia consequence.
  downstream:
  - target: Prolonged QT interval
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Cardiac potassium efflux channel inhibition: Slows phase 3 of the cardiac action potential, prolonging the QT interval and increasing the risk of torsades de pointes'
      explanation: Clinical synthesis supplies the repolarization consequence of potassium-current inhibition.
  - target: Ventricular Arrhythmogenesis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Cardiac potassium efflux channel inhibition: Slows phase 3 of the cardiac action potential, prolonging the QT interval and increasing the risk of torsades de pointes'
      explanation: Clinical synthesis supplies the repolarization consequence of potassium-current inhibition.
    description: Delayed repolarization can favor triggered polymorphic ventricular arrhythmia; this is distinct from the conduction-related route.
  - target: Torsade de pointes
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Cardiac potassium efflux channel inhibition: Slows phase 3 of the cardiac action potential, prolonging the QT interval and increasing the risk of torsades de pointes'
      explanation: Clinical synthesis supplies the repolarization consequence of potassium-current inhibition.
- name: Reduced Myocardial Contractility
  description: Myocardial depression reduces pump function in severe poisoning. Channel effects and dysrhythmias can contribute, but the cited clinical synthesis does not quantitatively separate these contributions.
  biological_scale: TISSUE
  biological_processes:
  - preferred_term: cardiac muscle contraction
    modifier: DECREASED
    term:
      id: GO:0060048
      label: cardiac muscle contraction
  cell_types:
  - preferred_term: ventricular cardiomyocyte
    term:
      id: CL:2000046
      label: ventricular cardiac muscle cell
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade.
    explanation: Identifies two contributors to hypotension; their relative importance varies.
  downstream:
  - target: Circulatory Failure
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16390222
      reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade.
      explanation: Identifies two contributors to hypotension; their relative importance varies.
- name: Vascular Alpha-1 Adrenergic Receptor Blockade
  description: Antagonism of vascular alpha-1 adrenergic signaling reduces vasoconstrictor tone and can contribute to hypotension.
  biological_scale: MOLECULAR
  molecular_functions:
  - preferred_term: alpha1-adrenergic receptor activity
    modifier: DECREASED
    term:
      id: GO:0004937
      label: alpha1-adrenergic receptor activity
  cell_types:
  - preferred_term: vascular smooth muscle cell
    term:
      id: CL:0000359
      label: vascular associated smooth muscle cell
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: 'Adrenergic receptor inhibition: Causes vasodilation, hypotension, and reflex tachycardia'
    explanation: Clinical synthesis links alpha-1 receptor inhibition to loss of vascular tone.
  downstream:
  - target: Reduced Systemic Vascular Resistance
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Adrenergic receptor inhibition: Causes vasodilation, hypotension, and reflex tachycardia'
      explanation: Clinical synthesis links alpha-1 receptor inhibition to loss of vascular tone.
- name: Reduced Systemic Vascular Resistance
  description: Vasodilation reduces systemic vascular resistance and contributes to low arterial pressure, with or without substantial myocardial depression.
  biological_scale: ORGANISM
  biological_processes:
  - preferred_term: vascular associated smooth muscle contraction
    modifier: DECREASED
    term:
      id: GO:0014829
      label: vascular associated smooth muscle contraction
  downstream:
  - target: Circulatory Failure
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16390222
      reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade.
      explanation: Identifies two contributors to hypotension; their relative importance varies.
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade.
    explanation: Identifies two contributors to hypotension; their relative importance varies.
- name: Circulatory Failure
  description: Inadequate circulatory function can reflect myocardial depression, dysrhythmia, vasodilation and volume-related contributions. Severe hypotension may progress to shock or arrest; shock is not necessarily purely cardiogenic.
  biological_scale: ORGANISM
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade.
    explanation: Identifies two contributors to hypotension; their relative importance varies.
  downstream:
  - target: Hypotension
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16390222
      reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade.
      explanation: Identifies two contributors to hypotension; their relative importance varies.
  - target: Shock
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33655968
      reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: all cases went into refractory shock and cardiac arrest despite adequate fluid resuscitation and sodium bicarbonate administration
      explanation: The literature review describes selected rescue cases with refractory shock; this is not a population rate.
  - target: Cardiac arrest
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33655968
      reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: At 200 minutes after ingestion, he experienced a TCA-induced cardiac arrest.
      explanation: Documents arrest during severe poisoning.
      quote_role: PRIMARY_RESULT
  - target: Systemic Acidaemia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:33655968
      reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: Laboratory analysis detected a substantially elevated serum lactate level
      explanation: The severe case documents elevated lactate; the perfusion-to-acidosis link is a physiological inference rather than an isolated causal test.
      quote_role: PRIMARY_RESULT
    description: Poor tissue perfusion can promote metabolic acidosis; respiratory compromise may contribute separately.
- name: Systemic Acidaemia
  description: Metabolic and respiratory acidosis can complicate severe poisoning. Hypoperfusion, inadequate ventilation and seizures can contribute. Lower pH increases the free pharmacologically active drug fraction and can aggravate cardiac sodium-channel toxicity, creating a feedback loop.
  biological_scale: ORGANISM
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Respiratory or metabolic acidosis increases the free, pharmacologically active TCA fraction, enhancing toxicity.
    explanation: Supports the pH-dependent availability mechanism without asserting complete channel binding by one ionization state.
  downstream:
  - target: Increased Free Tricyclic Antidepressant Fraction
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Respiratory or metabolic acidosis increases the free, pharmacologically active TCA fraction, enhancing toxicity.
      explanation: Supports the pH-dependent availability mechanism without asserting complete channel binding by one ionization state.
  - target: Cardiac Fast Sodium Channel Blockade
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Prevention of acidemia is critical because metabolic and respiratory acidosis increase TCA binding to cardiac sodium channels, increasing the risk of dysrhythmias and cardiac arrest.
      explanation: Supports aggravation of channel toxicity by acidemia.
  - target: Acidosis
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:3537621
      reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: There must be regular monitoring for hypoxia, acidosis and hypokalaemia
      explanation: The clinical review explicitly calls for monitoring for acidosis.
- name: Muscarinic Acetylcholine Receptor Antagonism
  description: Tricyclic drugs inhibit muscarinic receptor signaling, producing peripheral and central antimuscarinic manifestations. This toxidrome overlaps other poisonings and neither confirms TCA exposure nor excludes severe cardiotoxicity when absent.
  biological_scale: MOLECULAR
  molecular_functions:
  - preferred_term: muscarinic acetylcholine receptor activity
    modifier: DECREASED
    term:
      id: GO:0016907
      label: G protein-coupled acetylcholine receptor activity
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
    explanation: Clinical synthesis identifies the antimuscarinic branch.
  - reference: PMID:2996040
    reference_title: 'Amitriptylinoxide: receptor-binding profile compared with other antidepressant drugs.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    snippet: 'Half maximal inhibition of acetylcholine receptor binding occurred for amitriptylinoxide at 18 mumol/l (amitriptyline: 0.32 mumol/l).'
    explanation: The binding assay reports an amitriptyline inhibitory concentration; it does not establish identical potency for the entire class.
    quote_role: PRIMARY_RESULT
  downstream:
  - target: Sinus tachycardia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
      explanation: Clinical synthesis identifies the antimuscarinic branch.
  - target: Mydriasis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
      explanation: Clinical synthesis identifies the antimuscarinic branch.
  - target: Urinary retention
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
      explanation: Clinical synthesis identifies the antimuscarinic branch.
  - target: Dry skin
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
      explanation: Clinical synthesis identifies the antimuscarinic branch.
  - target: Delirium
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
      explanation: Clinical synthesis identifies the antimuscarinic branch.
  - target: Xerostomia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:3537621
      reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness.
      explanation: The clinical review includes this antimuscarinic finding.
  - target: Blurred vision
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:3537621
      reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness.
      explanation: The clinical review includes this antimuscarinic finding.
  - target: Reduced Gastrointestinal Motility
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: TCA poisoning produces anticholinergic effects that slow gastrointestinal motility, delaying absorption and peak drug concentrations.
      explanation: Links the antimuscarinic effect to impaired gut motility.
  - target: Hyperthermia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Hyperthermia is uncommon and generally results from the combined effects of biogenic amine reuptake inhibition and anticholinergic activity.
      explanation: The synthesis identifies combined contributors; no single receptor pathway is treated as sufficient.
- name: Neuronal Norepinephrine Reuptake Inhibition
  description: Inhibition of norepinephrine reuptake contributes to autonomic stimulation, including sinus tachycardia. TCAs also affect serotonin transport, but the cited cardiovascular causal link is specifically to norepinephrine uptake.
  biological_scale: MOLECULAR
  genes:
  - preferred_term: SLC6A2
    term:
      id: hgnc:11048
      label: SLC6A2
  molecular_functions:
  - preferred_term: norepinephrine reuptake transporter activity
    modifier: DECREASED
    term:
      id: GO:0005334
      label: norepinephrine:sodium symporter activity
  downstream:
  - target: Sinus tachycardia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:16390222
      reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Sinus tachycardia is the most common arrhythmia due to anticholinergic activity and inhibition of norepinephrine uptake by tricyclic antidepressants
      explanation: Identifies norepinephrine reuptake inhibition as a contribution to sinus tachycardia.
    description: Increased noradrenergic signaling contributes to sinus-rate acceleration.
  - target: Hyperthermia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Hyperthermia is uncommon and generally results from the combined effects of biogenic amine reuptake inhibition and anticholinergic activity.
      explanation: The synthesis identifies combined contributors; no single receptor pathway is treated as sufficient.
    description: The review refers to biogenic amines broadly; the specific noradrenergic contribution is inferred and need not be sufficient.
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Sinus tachycardia is the most common arrhythmia due to anticholinergic activity and inhibition of norepinephrine uptake by tricyclic antidepressants
    explanation: Identifies norepinephrine reuptake inhibition as a contribution to sinus tachycardia.
- name: Central Nervous System Depression
  description: Toxic exposure can cause drowsiness, reduced consciousness and coma, with impaired ventilation or airway protection in severe cases. Clinical severity is variable; coma is not an inevitable response to every toxic ingestion.
  biological_scale: ORGANISM
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Level of consciousness at presentation is the most sensitive clinical predictor of serious complications.
    explanation: The review identifies depressed consciousness as a clinical risk marker.
  - reference: PMID:42582545
    reference_title: 'Tricyclic Antidepressant Poisoning: A 6-year Retrospective Observational Cross-sectional Analysis of Emergency Department Presentation, Clinical Severity, and Hospital Outcomes in a Tertiary Academic Center.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: Clinical presentations included altered mental status (46.7%) and drowsiness (29.3%).
    explanation: The 75-person tertiary-center series reports altered consciousness and drowsiness; inclusion/exclusion criteria and pretreatment limit generalization.
    quote_role: PRIMARY_RESULT
  downstream:
  - target: Drowsiness
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:3537621
      reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness.
      explanation: Includes drowsiness among clinical findings.
  - target: Coma
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:3537621
      reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: In severe poisoning, there may be coma, convulsions, respiratory depression, hypotension and a wide range of electrocardiographic (ECG) abnormalities.
      explanation: Documents coma in severe poisoning without asserting that it is universal.
  - target: Respiratory depression
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:3537621
      reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: In severe poisoning, there may be coma, convulsions, respiratory depression, hypotension and a wide range of electrocardiographic (ECG) abnormalities.
      explanation: The cited manifestation is respiratory depression, not a measured diagnosis of respiratory failure.
  - target: Apnea
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
      reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Pulmonary complica- tions (e.g., respirat ory depression, sudde n apnea, aspiration pneumonia, adult-type respirat ory distress syndrome, and pulmonary edema) can be life threatening.
      explanation: The guideline explicitly lists severe pulmonary complications; this does not establish their incidence or one shared mechanism.
    description: Severe depressed ventilatory drive can progress to apnea, although the guideline does not isolate this route experimentally.
- name: Central Neuronal Hyperexcitability
  description: TCA poisoning can lower seizure threshold through multiple pharmacological and physiological influences. Experimental GABAA effects offer one possible route. A selected intubated/comatose case-control study associated post-admission seizures with death, but this is not a validated universal prognostic rule or evidence that QRS duration measures brain drug exposure.
  biological_scale: CELLULAR
  evidence:
  - reference: PMID:7618783
    reference_title: ECG lead aVR versus QRS interval in predicting seizures and arrhythmias in acute tricyclic antidepressant toxicity.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: Seizures occurred in 16 patients (20%) and ventricular arrhythmias in 5 (6%).
    explanation: Seizures occurred in 16 of 79 patients in the selected prospective poisoning cohort.
    quote_role: PRIMARY_RESULT
  - reference: PMID:21740136
    reference_title: Can death unrelated to secondary causes be predicted in intubated comatose tricyclic antidepressant-poisoned patients?
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: The only prognostic indicator of death in such patients is seizure after hospital presentation.
    explanation: This association applies to the study’s intubated, comatose case-control population.
    quote_role: PRIMARY_RESULT
  downstream:
  - target: Seizure
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:7618783
      reference_title: ECG lead aVR versus QRS interval in predicting seizures and arrhythmias in acute tricyclic antidepressant toxicity.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: Seizures occurred in 16 patients (20%) and ventricular arrhythmias in 5 (6%).
      explanation: Documents seizures in the cohort.
      quote_role: PRIMARY_RESULT
  - target: Status epilepticus
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33655968
      reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: His seizure stopped after intravenous administration of diazepam, and he was intubated because of his comatose status and generalized status epilepticus.
      explanation: Documents generalized status epilepticus in a severe case.
      quote_role: PRIMARY_RESULT
  - target: Systemic Acidaemia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Prevention measures include optimization of serum pH, seizure control to prevent acidosis, and magnesium administration to reduce the risk of torsades de pointes.
      explanation: The synthesis explicitly identifies seizure control as prevention of acidosis.
    description: Sustained convulsive activity can contribute to metabolic acidosis.
  - target: Agitation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Initial symptoms commonly include CNS manifestations, such as agitation, confusion, delirium, drowsiness, and seizures, as well as autonomic findings, including dry mouth and urinary retention.
      explanation: The chapter explicitly includes agitation.
    description: The clinical finding is observed; its specific molecular route is unresolved.
  - target: Hyperreflexia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Neurologic examination may demonstrate CNS depression, delirium, ankle clonus, hyperreflexia, or seizures.
      explanation: Lists this neurological finding without a frequency estimate.
    description: The clinical finding is observed; its specific molecular route is unresolved.
  - target: Ankle clonus
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Neurologic examination may demonstrate CNS depression, delirium, ankle clonus, hyperreflexia, or seizures.
      explanation: Specifically names ankle clonus.
    description: The clinical finding is observed; its specific molecular route is unresolved.
  - target: Tremor
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
      reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Other signs of TCA poisoning include palpita tions, tachycardia, hyperten- sion, ileus, tremors, myoclonu s, confusion, delirium, and lethargy.
      explanation: This is the guideline’s acute-poisoning clinical list; spacing in the PDF extraction is preserved.
    description: The clinical association is documented, with the specific molecular route unresolved.
  - target: Myoclonus
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
      reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Other signs of TCA poisoning include palpita tions, tachycardia, hyperten- sion, ileus, tremors, myoclonu s, confusion, delirium, and lethargy.
      explanation: This is the guideline’s acute-poisoning clinical list; spacing in the PDF extraction is preserved.
    description: The clinical association is documented, with the specific molecular route unresolved.
- name: Increased Free Tricyclic Antidepressant Fraction
  biological_scale: MOLECULAR
  description: Acidosis can increase the unbound pharmacologically active fraction of circulating TCA. A change in free fraction is distinct from an increase in total body drug amount.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Respiratory or metabolic acidosis increases the free, pharmacologically active TCA fraction, enhancing toxicity.
    explanation: Supports the pH-dependent availability mechanism without asserting complete channel binding by one ionization state.
  downstream:
  - target: Cardiac Fast Sodium Channel Blockade
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Therapeutic effects include restoration of inward cardiac sodium current and reduction of the free TCA fraction.
      explanation: The clinical synthesis links reduction of free drug with reversal of cardiac toxicity; the forward exposure-to-block relationship is a pharmacological inference.
    description: Greater unbound exposure can increase delivery to and inhibition of cardiac sodium channels.
- name: Reduced Gastrointestinal Motility
  biological_scale: TISSUE
  description: Antimuscarinic effects slow gastrointestinal motility, causing decreased bowel sounds and potentially ileus, while delaying absorption of ingested drug.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: TCA poisoning produces anticholinergic effects that slow gastrointestinal motility, delaying absorption and peak drug concentrations.
    explanation: Supports the gut-motility event.
  downstream:
  - target: Ileus
    causal_link_type: DIRECT
    evidence:
    - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
      reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Other signs of TCA poisoning include palpita tions, tachycardia, hyperten- sion, ileus, tremors, myoclonu s, confusion, delirium, and lethargy.
      explanation: This is the guideline’s acute-poisoning clinical list; spacing in the PDF extraction is preserved.
- name: Histamine H1 Receptor Inhibition
  biological_scale: MOLECULAR
  description: Histamine H1 receptor blockade contributes to TCA sedation. Profound coma is a clinical toxic effect with multiple possible contributions, not a receptor-specific readout.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK425165/
    reference_title: Amitriptyline Therapy and CYP2D6 and CYP2C19 Genotype - Medical Genetics Summaries - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: BACKGROUND
    snippet: Given that the tricyclics can also block different receptors (H1 histamine,
    explanation: The pharmacogenetic chapter identifies H1 receptor blockade among TCA actions.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: 'Histamine receptor inhibition: Produces sedation, altered mental status, and increased seizure risk'
    explanation: The synthesis describes a histamine-receptor contribution to sedation; it does not establish that this explains all coma.
  downstream:
  - target: Central Nervous System Depression
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'Histamine receptor inhibition: Produces sedation, altered mental status, and increased seizure risk'
      explanation: The synthesis describes a histamine-receptor contribution to sedation; it does not establish that this explains all coma.
    description: Reduced central histaminergic arousal is one contribution to depressed consciousness.
  genes:
  - preferred_term: HRH1
    term:
      id: hgnc:5182
      label: HRH1
  molecular_functions:
  - preferred_term: histamine H1 receptor activity
    modifier: DECREASED
    term:
      id: GO:0004969
      label: histamine receptor activity
- name: Reduced GABAA Receptor Current
  biological_scale: MOLECULAR
  description: Selected TCAs reduce GABA-elicited chloride current or uptake in experimental systems. Imipramine and nortriptyline inhibited recombinant α5β3γ2 receptors but had no significant effect on the tested α1β3γ2 subtype at 100 μM. Rat cortical assays also showed inhibition by amitriptyline. These findings support a possible contribution to neuroexcitation, not a proven single cause of clinical seizures.
  evidence:
  - reference: PMID:35088415
    reference_title: Tricyclic antipsychotics and antidepressants can inhibit α5-containing GABA(A) receptors by two distinct mechanisms.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: All of them diminished GABA‐elicited currents in α5β3γ2 receptors
    explanation: Includes imipramine and nortriptyline in recombinant oocytes; this does not demonstrate clinical seizure mediation.
  - reference: PMID:35088415
    reference_title: Tricyclic antipsychotics and antidepressants can inhibit α5-containing GABA(A) receptors by two distinct mechanisms.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: The chlorpromazine‐ levomepromazine‐ imipramine‐ nortriptyline group had no significant effects on the α1β3γ2 receptors at 100 μM.
    explanation: The negative comparator constrains generalization of the subtype-specific current inhibition.
  - reference: PMID:2456440
    reference_title: Antidepressants and seizure-interactions at the GABA-receptor chloride-ionophore complex.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: Using the method of GABA-stimulated 36Cl-uptake by rat cerebral cortical vesicles, we show that some antidepressant drugs (imipramine, amitryptyline, and mianserine) can inhibit the GABA-receptor chloride uptake
    explanation: Demonstrates inhibition in rat cortical vesicles; the source spells the drug names this way.
  - reference: PMID:9691231
    reference_title: Schild regression analysis of antidepressant and bicuculline antagonist effects at the GABAA receptor.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: It is concluded that neither the antidepressants studied nor bicuculline are pure competitive GABA antagonists at the GABAA receptor-chloride-ionophore complex in the rat cerebral cortex.
    explanation: Constrains a claim of simple competitive antagonism for the tested antidepressants.
  downstream:
  - target: Central Neuronal Hyperexcitability
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: 'aminobutyric acid (GABA) type A receptor antagonism: Reduces chloride conductance, causing neuroexcitation and seizures'
      explanation: The clinical synthesis proposes the inhibitory-transmission mechanism; subtype and experimental limits remain explicit.
    description: Reduced inhibitory signaling may contribute to seizure susceptibility, but the experiments do not establish its necessity or quantitative contribution in human overdose.
  molecular_functions:
  - preferred_term: GABA-A receptor activity
    modifier: DECREASED
    term:
      id: GO:0004890
      label: GABA-A receptor activity
phenotypes:
- category: Cardiovascular
  name: Prolonged QRS complex
  description: QRS widening reflects slowed intraventricular conduction and is an important serial risk marker. Historical cohorts associated widths of at least 100 ms with seizures and at least 160 ms with ventricular arrhythmias. These are imperfect clinical associations, not ingested-dose thresholds, and a normal initial QRS cannot exclude subsequent serious toxicity.
  phenotype_term:
    preferred_term: Prolonged QRS complex
    term:
      id: HP:0006677
      label: Prolonged QRS complex
  evidence:
  - reference: PMID:4022081
    reference_title: Value of the QRS duration versus the serum drug level in predicting seizures and ventricular arrhythmias after an acute overdose of tricyclic antidepressants.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: Seizures occurred at any QRS duration of 0.10 second or longer (P less than 0.05), but ventricular arrhythmias were seen only with a QRS duration of 0.16 second or longer (P less than 0.0005).
    explanation: Reports cohort-specific ECG associations, not absolute risk cutoffs or exposure levels.
    quote_role: PRIMARY_RESULT
- category: Cardiovascular
  name: Prolonged QT interval
  description: QT prolongation can reflect delayed repolarization and may be compounded by a widened QRS. Torsades is possible but uncommon in the clinical review.
  phenotype_term:
    preferred_term: Prolonged QT interval
    term:
      id: HP:0001657
      label: Prolonged QT interval
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: 'Cardiac potassium efflux channel inhibition: Slows phase 3 of the cardiac action potential, prolonging the QT interval and increasing the risk of torsades de pointes'
    explanation: Clinical synthesis supplies the repolarization consequence of potassium-current inhibition.
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Torsade de pointes occurs uncommonly.
    explanation: Qualifies the arrhythmia consequence.
- category: Cardiovascular
  name: Atrioventricular block
  description: Delayed or failed conduction through the atrioventricular node and infranodal tissue, from the same channel blockade that widens the QRS complex.
  phenotype_term:
    preferred_term: Atrioventricular block
    term:
      id: HP:0001678
      label: Atrioventricular block
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: bradyarrhythmias (due to atrioventricular block) and tachyarrhythmias (supraventricular and ventricular) may occur
    explanation: Names atrioventricular block as the cause of the bradyarrhythmias seen in this poisoning.
- category: Cardiovascular
  name: Ventricular tachycardia
  description: Ventricular tachycardia can occur during severe poisoning. Monomorphic tachycardia is associated with impaired conduction; polymorphic rhythms can also occur. Sinus tachycardia with a wide QRS may be difficult to distinguish from ventricular tachycardia.
  phenotype_term:
    preferred_term: Ventricular tachycardia
    term:
      id: HP:0004756
      label: Ventricular tachycardia
  evidence:
  - reference: PMID:3784839
    reference_title: Tricyclic antidepressant poisoning. Management of arrhythmias.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Ventricular tachycardia (monomorphic) is a consequence of impaired myocardial depolarisation and impulse conduction.
    explanation: Supports the clinical rhythm and its conduction-related mechanism; the aggregate ventricular-arrhythmia rate is not a VT-specific frequency.
- category: Cardiovascular
  name: Ventricular fibrillation
  description: Ventricular fibrillation is a potentially fatal rhythm reported in severe poisoning; the source does not establish a uniform reentrant mechanism.
  phenotype_term:
    preferred_term: Ventricular fibrillation
    term:
      id: HP:0001663
      label: Ventricular fibrillation
  evidence:
  - reference: PMID:21740136
    reference_title: Can death unrelated to secondary causes be predicted in intubated comatose tricyclic antidepressant-poisoned patients?
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: Ten cases and none of the controls had advanced ECG changes (ventricular fibrillation, torsades des pointes, or asystole).
    explanation: Fibrillation was included among advanced ECG abnormalities in the selected study; 10 refers to the aggregate ECG category, not fibrillation alone.
    quote_role: PRIMARY_RESULT
- category: Cardiovascular
  name: Cardiac arrest
  description: Loss of effective circulation can follow ventricular dysrhythmias or profound circulatory failure. Documented rhythms include ventricular tachycardia and pulseless electrical activity in a severe amitriptyline case.
  phenotype_term:
    preferred_term: Cardiac arrest
    term:
      id: HP:0001695
      label: Cardiac arrest
  evidence:
  - reference: PMID:33655968
    reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: At 200 minutes after ingestion, he experienced a TCA-induced cardiac arrest.
    explanation: Documents cardiac arrest attributed to the poisoning, with the interval from ingestion.
    quote_role: PRIMARY_RESULT
- category: Cardiovascular
  name: Hypotension
  description: Low arterial pressure may reflect myocardial depression, vasodilation and volume-related factors in differing proportions.
  phenotype_term:
    preferred_term: Hypotension
    term:
      id: HP:0002615
      label: Hypotension
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade.
    explanation: States both contributions to the hypotension.
- category: Cardiovascular
  name: Sinus tachycardia
  description: A common ECG finding associated with antimuscarinic activity and norepinephrine reuptake inhibition. With QRS widening it can resemble ventricular tachycardia; its presence does not exclude serious toxicity.
  phenotype_term:
    preferred_term: Sinus tachycardia
    term:
      id: HP:0011703
      label: Sinus tachycardia
  evidence:
  - reference: PMID:10452441
    reference_title: ECG abnormalities in tricyclic antidepressant ingestion.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Aside from the sinus tachycardia due principally to anticholinergic effects, TCA-toxic changes seen on the ECG are attributable primarily to the sodium channel blockade caused by these agents.
    explanation: Separates the sinus tachycardia, which is anticholinergic, from the rest of the electrocardiographic picture, which is not.
  - reference: PMID:3784839
    reference_title: Tricyclic antidepressant poisoning. Management of arrhythmias.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Sinus tachycardia with QRS prolongation may be difficult to distinguish from ventricular tachycardia.
    explanation: Supports the bedside-confusion claim made in this phenotype's description and in the Ventricular tachycardia one.
- category: Neurologic
  name: Coma
  description: Profoundly depressed consciousness can occur in severe poisoning and may require airway protection. It is not inevitable after every toxic ingestion.
  phenotype_term:
    preferred_term: Coma
    term:
      id: HP:0001259
      label: Coma
  evidence:
  - reference: PMID:3537621
    reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: In severe poisoning, there may be coma, convulsions, respiratory depression, hypotension and a wide range of electrocardiographic (ECG) abnormalities.
    explanation: The review includes coma among severe manifestations.
- category: Neurologic
  name: Seizure
  description: Convulsive seizures occurred in 16/79 patients in one prospective poisoning cohort. Drug-specific risk and severity selection affect reported rates, so no disease-wide frequency is assigned. In a separate intubated/comatose case-control study, seizures after hospital arrival were associated with death.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:7618783
    reference_title: ECG lead aVR versus QRS interval in predicting seizures and arrhythmias in acute tricyclic antidepressant toxicity.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: Seizures occurred in 16 patients (20%) and ventricular arrhythmias in 5 (6%).
    explanation: The denominator is 79 selected patients; no pooled disease frequency is inferred.
    quote_role: PRIMARY_RESULT
  - reference: PMID:21740136
    reference_title: Can death unrelated to secondary causes be predicted in intubated comatose tricyclic antidepressant-poisoned patients?
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: The only prognostic indicator of death in such patients is seizure after hospital presentation.
    explanation: Restricted to the study’s intubated/comatose case-control population.
    quote_role: PRIMARY_RESULT
  - reference: PMID:7904010
    reference_title: Greater toxicity in overdose of dothiepin than of other tricyclic antidepressants.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: The odds ratio for seizures with dothiepin versus other TCAs was 6.7 (95% Cl 2.2-20.7) unadjusted and 7.1 (2.2-23.2) after adjustment for sex, age, and ingested dose.
    explanation: Reports a drug-specific association after adjustment, not proof that dose or all confounding was eliminated.
    quote_role: PRIMARY_RESULT
- category: Neurologic
  name: Status epilepticus
  description: Continuing or repeated seizure activity without recovery between events, requiring anticonvulsant treatment and usually intubation.
  phenotype_term:
    preferred_term: Status epilepticus
    term:
      id: HP:0002133
      label: Status epilepticus
  evidence:
  - reference: PMID:33655968
    reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: His seizure stopped after intravenous administration of diazepam, and he was intubated because of his comatose status and generalized status epilepticus.
    explanation: Documents generalized status epilepticus, and its response to a benzodiazepine, in an amitriptyline overdose.
    quote_role: PRIMARY_RESULT
- category: Metabolic
  name: Acidosis
  description: Respiratory or metabolic acidosis can aggravate toxicity. The broad term is retained because both mechanisms may occur.
  phenotype_term:
    preferred_term: Acidosis
    term:
      id: HP:0001941
      label: Acidosis
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Respiratory or metabolic acidosis increases the free, pharmacologically active TCA fraction, enhancing toxicity.
    explanation: Supports the pH-dependent availability mechanism without asserting complete channel binding by one ionization state.
- category: Ophthalmologic
  name: Mydriasis
  description: Pupillary dilation is part of the antimuscarinic clinical picture, which overlaps other intoxications.
  phenotype_term:
    preferred_term: Mydriasis
    term:
      id: HP:0011499
      label: Mydriasis
  evidence:
  - reference: PMID:3537621
    reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness.
    explanation: Lists dilated pupils among the commonest clinical features.
- category: Gastrointestinal
  name: Xerostomia
  description: Dry mouth from muscarinic blockade of salivary secretion.
  phenotype_term:
    preferred_term: Xerostomia
    term:
      id: HP:0000217
      label: Xerostomia
  evidence:
  - reference: PMID:3537621
    reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness.
    explanation: Lists dry mouth among the commonest clinical features.
- category: Ophthalmologic
  name: Blurred vision
  description: Blurred vision is reported among antimuscarinic manifestations.
  phenotype_term:
    preferred_term: Blurred vision
    term:
      id: HP:0000622
      label: Blurred vision
  evidence:
  - reference: PMID:3537621
    reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness.
    explanation: Lists blurred vision among the commonest clinical features.
- category: Cardiovascular
  name: Right bundle branch block
  description: Right bundle branch block is described with a drug-induced Brugada-pattern tracing in the clinical review. The source does not specify complete block or establish an inherited Brugada syndrome.
  phenotype_term:
    preferred_term: Right bundle branch block
    term:
      id: HP:0011710
      label: Bundle branch block
    coarse_binding_basis: NO_HPO_TERM
    term_gap: Live HPO search in September 2026 found complete and incomplete right bundle branch block, but no unqualified right-sided term. The review does not specify completeness, so the parent bundle-branch-block term preserves the supported scope.
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Electrocardiographic changes include prolongation of the PR, QRS and QT intervals, nonspecific ST segment and T wave changes, atrioventricular block, right axis deviation of the terminal 40 ms vector of the QRS complex in the frontal plane (T 40 ms axis) and the Brugada pattern (downsloping ST segment elevation in leads V1-V3 in association with right bundle branch block).
    explanation: Describes the Brugada pattern of this poisoning as right bundle branch block with right precordial ST elevation.
- category: Cardiovascular
  name: Shock
  description: Refractory shock is reported in severe rescue cases. The cited review does not establish that every case has exclusively cardiogenic shock.
  phenotype_term:
    preferred_term: Shock
    term:
      id: HP:0031273
      label: Shock
  evidence:
  - reference: PMID:33655968
    reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: all cases went into refractory shock and cardiac arrest despite adequate fluid resuscitation and sodium bicarbonate administration
    explanation: Describes the selected published rescue cases, without a disease-wide rate or a pure cardiogenic classification.
- category: Respiratory
  name: Respiratory depression
  description: Depressed ventilation can accompany severe central nervous system toxicity. This term matches the reported respiratory depression; the cited general review does not provide blood-gas criteria for respiratory failure.
  phenotype_term:
    preferred_term: Respiratory depression
    term:
      id: HP:0002791
      label: Hypoventilation
  evidence:
  - reference: PMID:3537621
    reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: In severe poisoning, there may be coma, convulsions, respiratory depression, hypotension and a wide range of electrocardiographic (ECG) abnormalities.
    explanation: Directly names respiratory depression.
- name: Urinary retention
  description: Reported in the clinical spectrum of acute TCA poisoning; expression varies with the exposure and severity.
  phenotype_term:
    preferred_term: Urinary retention
    term:
      id: HP:0000016
      label: Urinary retention
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
    explanation: Clinical synthesis identifies the antimuscarinic branch.
- name: Dry skin
  description: Reported in the clinical spectrum of acute TCA poisoning; expression varies with the exposure and severity.
  phenotype_term:
    preferred_term: Dry skin
    term:
      id: HP:0000958
      label: Dry skin
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
    explanation: Clinical synthesis identifies the antimuscarinic branch.
- name: Delirium
  description: Reported in the clinical spectrum of acute TCA poisoning; expression varies with the exposure and severity.
  phenotype_term:
    preferred_term: Delirium
    term:
      id: HP:0031258
      label: Delirium
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: 'Muscarinic receptor inhibition: Leads to antimuscarinic (anticholinergic) effects, including tachycardia, mydriasis, urinary retention, decreased bowel sounds, dry skin, and delirium'
    explanation: Clinical synthesis identifies the antimuscarinic branch.
- name: Agitation
  description: Reported in the clinical spectrum of acute TCA poisoning; expression varies with the exposure and severity.
  phenotype_term:
    preferred_term: Agitation
    term:
      id: HP:0000713
      label: Agitation
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Initial symptoms commonly include CNS manifestations, such as agitation, confusion, delirium, drowsiness, and seizures, as well as autonomic findings, including dry mouth and urinary retention.
    explanation: The chapter explicitly includes agitation.
- name: Drowsiness
  description: Reported in the clinical spectrum of acute TCA poisoning; expression varies with the exposure and severity.
  phenotype_term:
    preferred_term: Drowsiness
    term:
      id: HP:0002329
      label: Drowsiness
  evidence:
  - reference: PMID:3537621
    reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness.
    explanation: Explicitly includes drowsiness.
- name: Hyperreflexia
  description: Reported in the clinical spectrum of acute TCA poisoning; expression varies with the exposure and severity.
  phenotype_term:
    preferred_term: Hyperreflexia
    term:
      id: HP:0001347
      label: Hyperreflexia
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Neurologic examination may demonstrate CNS depression, delirium, ankle clonus, hyperreflexia, or seizures.
    explanation: Lists this neurological finding without a frequency estimate.
- name: Ankle clonus
  description: Reported in the clinical spectrum of acute TCA poisoning; expression varies with the exposure and severity.
  phenotype_term:
    preferred_term: Ankle clonus
    term:
      id: HP:0011448
      label: Ankle clonus
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Neurologic examination may demonstrate CNS depression, delirium, ankle clonus, hyperreflexia, or seizures.
    explanation: Specifically names ankle clonus.
- name: Hyperthermia
  description: Elevated body temperature can occur in severe poisoning through combined antimuscarinic and amine-related effects. It can aggravate toxicity and cause secondary complications.
  phenotype_term:
    preferred_term: Hyperthermia
    term:
      id: HP:0001945
      label: Fever
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Physical examination may reveal tachycardia, hypotension, and, in severe cases, hyperthermia.
    explanation: Documents hyperthermia in severe toxicity without a disease-wide frequency.
- name: Ileus
  description: Included among signs of TCA poisoning in the consensus guideline; no general frequency is inferred.
  phenotype_term:
    preferred_term: Ileus
    term:
      id: HP:0002595
      label: Ileus
  evidence:
  - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Other signs of TCA poisoning include palpita tions, tachycardia, hyperten- sion, ileus, tremors, myoclonu s, confusion, delirium, and lethargy.
    explanation: This is the guideline’s acute-poisoning clinical list; spacing in the PDF extraction is preserved.
- name: Tremor
  description: Included among signs of TCA poisoning in the consensus guideline; no general frequency is inferred.
  phenotype_term:
    preferred_term: Tremor
    term:
      id: HP:0001337
      label: Tremor
  evidence:
  - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Other signs of TCA poisoning include palpita tions, tachycardia, hyperten- sion, ileus, tremors, myoclonu s, confusion, delirium, and lethargy.
    explanation: This is the guideline’s acute-poisoning clinical list; spacing in the PDF extraction is preserved.
- name: Myoclonus
  description: Included among signs of TCA poisoning in the consensus guideline; no general frequency is inferred.
  phenotype_term:
    preferred_term: Myoclonus
    term:
      id: HP:0001336
      label: Myoclonus
  evidence:
  - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Other signs of TCA poisoning include palpita tions, tachycardia, hyperten- sion, ileus, tremors, myoclonu s, confusion, delirium, and lethargy.
    explanation: This is the guideline’s acute-poisoning clinical list; spacing in the PDF extraction is preserved.
- name: Torsade de pointes
  description: An uncommon but documented polymorphic ventricular tachycardia associated with delayed repolarization; other ventricular arrhythmias also occur.
  phenotype_term:
    preferred_term: Torsade de pointes
    term:
      id: HP:0001664
      label: Torsade de pointes
  evidence:
  - reference: PMID:16390222
    reference_title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Torsade de pointes occurs uncommonly.
    explanation: The qualitative source does not justify a numerical frequency band.
- name: Apnea
  description: Reported as a potentially severe pulmonary complication of TCA poisoning. It is not present in every case, and the guideline does not give a complication-specific denominator.
  phenotype_term:
    preferred_term: Apnea
    term:
      id: HP:0002104
      label: Apnea
  evidence:
  - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Pulmonary complica- tions (e.g., respirat ory depression, sudde n apnea, aspiration pneumonia, adult-type respirat ory distress syndrome, and pulmonary edema) can be life threatening.
    explanation: The guideline explicitly lists severe pulmonary complications; this does not establish their incidence or one shared mechanism.
- name: Aspiration pneumonia
  description: Reported as a potentially severe pulmonary complication of TCA poisoning. It is not present in every case, and the guideline does not give a complication-specific denominator.
  phenotype_term:
    preferred_term: Aspiration pneumonia
    term:
      id: HP:0011951
      label: Aspiration pneumonia
  evidence:
  - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Pulmonary complica- tions (e.g., respirat ory depression, sudde n apnea, aspiration pneumonia, adult-type respirat ory distress syndrome, and pulmonary edema) can be life threatening.
    explanation: The guideline explicitly lists severe pulmonary complications; this does not establish their incidence or one shared mechanism.
- name: Pulmonary edema
  description: Reported as a potentially severe pulmonary complication of TCA poisoning. It is not present in every case, and the guideline does not give a complication-specific denominator.
  phenotype_term:
    preferred_term: Pulmonary edema
    term:
      id: HP:0100598
      label: Pulmonary edema
  evidence:
  - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Pulmonary complica- tions (e.g., respirat ory depression, sudde n apnea, aspiration pneumonia, adult-type respirat ory distress syndrome, and pulmonary edema) can be life threatening.
    explanation: The guideline explicitly lists severe pulmonary complications; this does not establish their incidence or one shared mechanism.
genetic:
- name: CYP2D6
  gene_term:
    preferred_term: CYP2D6
    term:
      id: hgnc:2625
      label: CYP2D6
  relationship_type: MODIFIER
  association: CYP2D6 activity affects therapeutic TCA exposure; poor metabolizers can have higher plasma concentrations at usual doses. This pharmacokinetic modifier is not a genetic cause of poisoning, and the cited guidance does not validate CYP2D6 genotype as a predictor of acute-overdose outcome.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK425165/
    reference_title: Amitriptyline Therapy and CYP2D6 and CYP2C19 Genotype - Medical Genetics Summaries - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The FDA-approved drug label for amitriptyline states that CYP2D6 PM have higher than expected plasma concentrations of tricyclic antidepressants when given usual doses.
    explanation: The claim concerns therapeutic-dose plasma exposure, not acute-poisoning prognosis.
  notes: CYP2D6 inhibitors can also alter exposure; genotype-guided therapeutic prescribing should not be substituted for immediate clinical and ECG assessment of poisoning.
- name: CYP2C19
  gene_term:
    preferred_term: CYP2C19
    term:
      id: hgnc:2621
      label: CYP2C19
  relationship_type: MODIFIER
  association: CYP2C19 contributes to demethylation of amitriptyline to active nortriptyline. Altered activity can change the parent-to-metabolite balance; this is not equivalent to removing all pharmacological activity. Therapeutic pharmacogenetic recommendations do not establish acute-overdose outcome prediction.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK425165/
    reference_title: Amitriptyline Therapy and CYP2D6 and CYP2C19 Genotype - Medical Genetics Summaries - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: Metabolism by CYP2C19 results in active metabolites, including nortriptyline, which is also a tricyclic antidepressant
    explanation: Directly identifies the active metabolite.
environmental:
- name: Ingestion of a tricyclic antidepressant in overdose
  description: Excessive TCA ingestion can be intentional, accidental or related to medication error. Different drugs have different observed overdose toxicity, and dose estimates, coingestants and patient factors limit individual prediction.
  effect: Causes acute tricyclic antidepressant poisoning
  exposure_term:
    preferred_term: exposure to tricyclic antidepressants
    term:
      id: ECTO:2000024
      label: exposure to tricyclic antidepressants
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Intentional self-harm is the leading cause of TCA overdose in adults.
    explanation: Describes adult exposure context.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: In children, accidental or exploratory ingestions can cause significant toxicity because of the narrow therapeutic index of these drugs.
    explanation: Includes the pediatric accidental-exposure setting.
  - reference: PMID:20435959
    reference_title: 'Toxicity of antidepressants: rates of suicide relative to prescribing and non-fatal overdose.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: Within the TCAs, compared with amitriptyline both dosulepin (relative toxicity index 2.7) and doxepin (2.6) were more toxic.
    explanation: The observational comparison found higher relative toxicity indices for dosulepin and doxepin than amitriptyline; the two drugs differ from the pair highlighted in the separate cardiovascular review.
    quote_role: PRIMARY_RESULT
  influences_mechanisms:
  - target: Systemic Tricyclic Antidepressant Burden
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT
    description: The ingestion is the route by which the systemic drug burden is established. Everything else in the entry is downstream of it.
    evidence:
    - reference: PMID:17453872
      reference_title: 'Tricyclic antidepressant poisoning: an evidence-based consensus guideline for out-of-hospital management.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: BACKGROUND
      snippet: A review of U.S. poison center data for 2004 showed over 12,000 exposures to tricyclic antidepressants (TCAs).
      explanation: Establishes ingestion exposure as the event poison-control systems record and triage, which is the exposure this link names.
  notes: Relative toxicity indices compare selected population data and do not yield a patient-specific fatality probability. Exposure is acquired; inherited pharmacokinetic variation is a modifier rather than a requirement.
treatments:
- name: Sodium Bicarbonate
  description: Core therapy for clinically important TCA cardiotoxicity, including hemodynamic instability, QRS widening and dysrhythmias. Sodium loading and alkalinization can improve sodium-current-dependent conduction and reduce active free drug. Serial ECG, pH and electrolytes guide treatment; excessive alkalemia, sodium loading and hypokalemia are relevant limits. The optimal endpoint and maintenance strategy are not settled by the experimental comparisons.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: sodium bicarbonate
      term:
        id: NCIT:C29457
        label: Sodium Bicarbonate
  target_mechanisms:
  - target: Cardiac Fast Sodium Channel Blockade
    treatment_effect: INHIBITS
    evidence:
    - reference: PMID:6092616
      reference_title: Mechanism of reversal of toxic effects of amitriptyline on cardiac Purkinje fibers by sodium bicarbonate.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: The results suggest that the beneficial effects of NaHCO3 are related to a reversal of drug effects on phase 0 characteristics and that this effect is due both to alkalinization and to increases in extracellular Na concentration.
      explanation: The isolated-fiber experiments support contributions from both sodium and pH; they do not establish complete reversal or one dominant clinical mechanism.
    description: Improves the functional conduction consequences of blockade; molecular displacement and complete reversal are not established by clinical ECG improvement.
  - target: Systemic Acidaemia
    treatment_effect: INHIBITS
    evidence:
    - reference: PMID:3784839
      reference_title: Tricyclic antidepressant poisoning. Management of arrhythmias.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Hypertonic sodium bicarbonate is of particular benefit in patients who are acidotic, since acidosis aggravates cardiac toxicity.
      explanation: Supports correction of acidemia as part of care.
  - target: Increased Free Tricyclic Antidepressant Fraction
    treatment_effect: INHIBITS
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Therapeutic effects include restoration of inward cardiac sodium current and reduction of the free TCA fraction.
      explanation: The chapter describes reduction of the active free fraction.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Sodium bicarbonate is indicated for hemodynamic instability, acidemia, seizures, or QRS prolongation greater than 100 milliseconds.
    explanation: The contemporary chapter gives clinical indications; ECG values are interpreted alongside symptoms and hemodynamics.
  - reference: PMID:6092616
    reference_title: Mechanism of reversal of toxic effects of amitriptyline on cardiac Purkinje fibers by sodium bicarbonate.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    snippet: The results suggest that the beneficial effects of NaHCO3 are related to a reversal of drug effects on phase 0 characteristics and that this effect is due both to alkalinization and to increases in extracellular Na concentration.
    explanation: The isolated-fiber experiments support contributions from both sodium and pH; they do not establish complete reversal or one dominant clinical mechanism.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Hypokalemia commonly develops during sodium bicarbonate therapy
    explanation: Supports monitoring for a treatment-related electrolyte complication.
  action_category: THERAPEUTIC
- name: Hypertonic Saline
  description: Additional sodium loading has been studied experimentally and may be considered by toxicology specialists in refractory sodium-channel toxicity when further alkalinization is limited. Animal results do not demonstrate superiority to bicarbonate in human poisoning. Sodium and acid-base monitoring are necessary.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: hypertonic saline
      term:
        id: NCIT:C60814
        label: Hypertonic Saline
  target_mechanisms:
  - target: Slowed Cardiac Phase 0 Depolarization
    treatment_effect: MODULATES
    evidence:
    - reference: PMID:6092616
      reference_title: Mechanism of reversal of toxic effects of amitriptyline on cardiac Purkinje fibers by sodium bicarbonate.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: The results suggest that the beneficial effects of NaHCO3 are related to a reversal of drug effects on phase 0 characteristics and that this effect is due both to alkalinization and to increases in extracellular Na concentration.
      explanation: The isolated-fiber experiments support contributions from both sodium and pH; they do not establish complete reversal or one dominant clinical mechanism.
    description: Experimental sodium loading can improve depressed phase 0 characteristics; clinical rescue efficacy is less certain.
  evidence:
  - reference: PMID:20507243
    reference_title: What is the role of lidocaine or phenytoin in tricyclic antidepressant-induced cardiotoxicity?
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Primary treatment strategies include sodium bicarbonate, hypertonic saline, and correction of any conditions that may aggravate this toxicity such as acidosis, hyperthermia, and hypotension.
    explanation: The review includes hypertonic saline among treatment strategies; it does not rank it above bicarbonate.
  - reference: PMID:9737495
    reference_title: 'Experimental tricyclic antidepressant toxicity: a randomized, controlled comparison of hypertonic saline solution, sodium bicarbonate, and hyperventilation.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    snippet: Mean QRS duration 10 minutes after treatment was 144+/-38 ms in the control group, 80+/-14 ms in the HTS group, 105+/-38 ms in the NaHCO3 group, and 125+/-46 ms in the HV group (P<.05).
    explanation: The swine study used different sodium doses in the saline and bicarbonate arms, limiting mechanistic comparison.
    quote_role: PRIMARY_RESULT
  action_category: THERAPEUTIC
- name: Activated Charcoal
  description: Selected gastrointestinal decontamination can adsorb unabsorbed TCA. Use requires an appropriate airway and assessment of aspiration or gastrointestinal contraindications; it must not delay transport or resuscitation. A trial comparing three active charcoal/decontamination regimens had no untreated control, so no difference between arms does not establish absence of benefit.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: activated charcoal
      term:
        id: CHEBI:91090
        label: charcoal
  target_mechanisms:
  - target: Systemic Tricyclic Antidepressant Burden
    treatment_effect: MODULATES
    evidence:
    - reference: PMID:11060957
      reference_title: Tricyclic antidepressant poisoning.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Activated charcoal binds tricyclic antidepressants.
      explanation: Supports luminal adsorption; reduced exposure and outcome benefit depend on timing and selection.
    description: Adsorption of drug remaining in the gastrointestinal tract can reduce further absorption; it does not remove drug already distributed in tissues.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Gastrointestinal decontamination with activated charcoal should only be performed in patients with a protected airway who are not vomiting.
    explanation: Defines selection and airway safety rather than recommending routine administration.
  - reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    reference_title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Prehospital activated charcoal administration, if available, should only be carried out by health professionals and only if no contraindications are present. Do not delay transportation in order to administer activated charcoal (Grades B/D).
    explanation: The 2007 prehospital guideline gives a conditional professional-use recommendation.
  action_category: THERAPEUTIC
- name: Benzodiazepine Anticonvulsant Therapy
  description: Benzodiazepines are first-line therapy for TCA-associated convulsions. Refractory seizures may require phenobarbital or propofol with airway protection. Seizure control also limits secondary acidosis; prognosis from selected severe cohorts should not be treated as a universal rule.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: diazepam
      term:
        id: NCIT:C28982
        label: Diazepam
  target_mechanisms:
  - target: Central Neuronal Hyperexcitability
    treatment_effect: INHIBITS
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: TCA-induced seizures generally respond to benzodiazepines or other GABA agonists.
      explanation: Supports benzodiazepines for toxin-induced seizures.
  - target: Status epilepticus
    treatment_effect: INHIBITS
    evidence:
    - reference: PMID:33655968
      reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: His seizure stopped after intravenous administration of diazepam, and he was intubated because of his comatose status and generalized status epilepticus.
      explanation: A severe case documents diazepam use and seizure termination; it is not a comparative efficacy study.
      quote_role: PRIMARY_RESULT
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: TCA-induced seizures generally respond to benzodiazepines or other GABA agonists.
    explanation: Supports benzodiazepines for toxin-induced seizures.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Refractory seizures may require phenobarbital or propofol, typically after endotracheal intubation for airway protection.
    explanation: Provides the escalation context.
  action_category: THERAPEUTIC
- name: Intravenous Fluid Resuscitation
  description: Intravenous fluids support circulation when hypotension has a volume-responsive component, alongside bicarbonate and other indicated resuscitation. Persistent instability requires escalation; the source does not establish a mandatory fluids-first delay or routine central venous pressure monitoring.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Fluid Therapy
    term:
      id: NCIT:C116537
      label: Fluid Therapy
  target_mechanisms:
  - target: Circulatory Failure
    treatment_effect: MODULATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Initial management of hypotension includes intravenous fluids and sodium bicarbonate.
      explanation: Supports both early interventions without a rigid sequence that delays bicarbonate.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Initial management of hypotension includes intravenous fluids and sodium bicarbonate.
    explanation: Supports both early interventions without a rigid sequence that delays bicarbonate.
  action_category: THERAPEUTIC
- name: Vasopressor Support
  description: Vasopressors, commonly norepinephrine, may be needed for persistent hypotension despite initial resuscitation. Support is individualized with bicarbonate and other care; animal comparisons of catecholamines do not establish the best human regimen.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: norepinephrine bitartrate
      term:
        id: NCIT:C48646
        label: Norepinephrine Bitartrate
    - preferred_term: epinephrine
      term:
        id: CHEBI:33568
        label: adrenaline
  target_mechanisms:
  - target: Reduced Systemic Vascular Resistance
    treatment_effect: INHIBITS
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Persistent hypotension may require &#x003b1;-adrenergic vasopressors, such as norepinephrine.
      explanation: The current chapter supports norepinephrine for persistent hypotension.
    description: Alpha-adrenergic support can restore vascular tone; no receptor-occupancy competition was measured in the cited clinical source.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Persistent hypotension may require &#x003b1;-adrenergic vasopressors, such as norepinephrine.
    explanation: The current chapter supports norepinephrine for persistent hypotension.
  action_category: THERAPEUTIC
- name: Lidocaine
  description: Class Ib antiarrhythmic rescue may be considered for life-threatening TCA ventricular dysrhythmias refractory to bicarbonate, with specialist input. Experimental channel-recovery kinetics provide a rationale but vary by TCA and do not prove a universal displacement mechanism.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: lidocaine
      term:
        id: CHEBI:6456
        label: lidocaine
  target_mechanisms:
  - target: Ventricular Arrhythmogenesis
    treatment_effect: MODULATES
    evidence:
    - reference: PMID:20507243
      reference_title: What is the role of lidocaine or phenytoin in tricyclic antidepressant-induced cardiotoxicity?
      supports: SUPPORT
      directness: DIRECT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: Sodium channels have faster recovery times after exposure to lidocaine (1-2 s) and phenytoin (0.71 s), than with some TCAs such as amitriptyline (13.6 s), but not others (e.g., imipramine at 1.6 s).
      explanation: Different experimental recovery kinetics support a possible rationale; they do not directly demonstrate clinical arrhythmia prevention.
    description: Intended to suppress refractory ventricular dysrhythmias; an established molecular reversal of TCA occupancy is not claimed.
  evidence:
  - reference: PMID:20507243
    reference_title: What is the role of lidocaine or phenytoin in tricyclic antidepressant-induced cardiotoxicity?
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: We recommend the use of lidocaine in cases in which cardiotoxicity (arrhythmias, hypotension) is refractory to treatment with sodium bicarbonate or hypertonic saline
    explanation: The review supports possible use; current guidance distinguishes limited-evidence class Ib rescue from routine use.
  action_category: THERAPEUTIC
- name: Intravenous Lipid Emulsion
  description: A potential rescue option for severe lipophilic-TCA toxicity after standard therapies fail, supported by low-certainty guidance and case reports. Animal experiments show drug redistribution without consistent hemodynamic benefit. Lower brain concentration or a lower tissue-to-plasma ratio does not mean total body TCA burden has fallen.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Circulatory Failure
    treatment_effect: MODULATES
    evidence:
    - reference: PMID:22244291
      reference_title: '"Lipid rescue" for tricyclic antidepressant cardiotoxicity.'
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: We report a case of dothiepin (tricyclic antidepressant) overdose causing refractory cardiovascular collapse, which seemed to be successfully reversed with lipid-emulsion therapy
      explanation: The case supplies limited clinical support for rescue of cardiovascular collapse.
      quote_role: PRIMARY_RESULT
    description: A proposed rescue of hemodynamic failure, with uncertain efficacy; not an assertion that total systemic drug burden is eliminated.
  evidence:
  - reference: PMID:27608281
    reference_title: Evidence-based recommendations on the use of intravenous lipid emulsion therapy in poisoning().
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: if other therapies fail, we recommend ILE for bupivacaine toxicity and we suggest using ILE for toxicity due to other LAs, amitriptyline, and bupropion
    explanation: The recommendation is for rescue after failure of other treatments.
  - reference: PMID:27608281
    reference_title: Evidence-based recommendations on the use of intravenous lipid emulsion therapy in poisoning().
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: All recommendations were based on very low quality of evidence.
    explanation: Qualifies certainty.
  - reference: PMID:23639060
    reference_title: Intravenous lipid emulsion entraps amitriptyline into plasma and can lower its brain concentration--an experimental intoxication study in pigs.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    snippet: In spite of the entrapment, there was no difference in haemodynamics between the groups.
    explanation: This protocol showed no hemodynamic advantage despite redistribution; it is a limitation, not a vote against all possible rescue settings.
  - reference: PMID:25377397
    reference_title: 'Intravenous lipid emulsion therapy does not improve hypotension compared to sodium bicarbonate for tricyclic antidepressant toxicity: a randomized, controlled pilot study in a swine model.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    quote_role: PRIMARY_RESULT
    snippet: Intravenous lipid emulsion treatment failed to improve amitriptyline-induced hypotension when compared to the standard treatment of sodium bicarbonate in a large animal model of severe TCA overdose.
    explanation: Negative comparison in a small swine pilot, with high mortality and limited power.
  - reference: PMID:22244291
    reference_title: '"Lipid rescue" for tricyclic antidepressant cardiotoxicity.'
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: We report a case of dothiepin (tricyclic antidepressant) overdose causing refractory cardiovascular collapse, which seemed to be successfully reversed with lipid-emulsion therapy
    explanation: The uncontrolled case reports apparent improvement during rescue care, without isolating ILE efficacy.
    quote_role: PRIMARY_RESULT
  action_category: THERAPEUTIC
  notes: Guideline recommendations against routine first-line use and suggestions for rescue address different clinical questions. A count of SUPPORT and REFUTE snippets is not an evidence synthesis. A formulation-specific agent is not bound because the cited non-local-anesthetic guidance does not establish one preferred formulation.
- name: Veno-Arterial Extracorporeal Membrane Oxygenation
  description: Extracorporeal circulatory support may be considered for refractory shock or cardiac arrest despite conventional resuscitation. It can provide a bridge through potentially reversible poisoning, but recovery time and neurological outcome vary. Published rescue cases with concurrent treatments do not establish isolated efficacy.
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: veno-arterial extracorporeal membrane oxygenation
    term:
      id: NCIT:C171507
      label: Extracorporeal Membrane Oxygenation
  target_mechanisms:
  - target: Circulatory Failure
    treatment_effect: BYPASSES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Rare cases may require advanced support with extracorporeal membrane oxygenation.
      explanation: Supports rescue-level mechanical support.
    description: Provides mechanical circulatory support while toxicity and organ dysfunction are treated; it does not directly remove sodium-channel blockade.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Rare cases may require advanced support with extracorporeal membrane oxygenation.
    explanation: Supports rescue-level mechanical support.
  - reference: PMID:33655968
    reference_title: 'Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: Twenty seven hours after starting the pump, the patient was weaned off the VA-ECMO.
    explanation: Documents the time course of one case, not a universal duration.
  action_category: THERAPEUTIC
- name: Mechanical Ventilation
  description: Airway protection and ventilatory support are used for inadequate ventilation, loss of airway protection or treatment of refractory seizures. Avoiding respiratory acidosis is important during intubation and subsequent care. Controlled hyperventilation may be an adjunct in already ventilated life-threatening sodium-channel poisoning; this does not establish a routine prophylactic-intubation indication. Neuromuscular paralysis does not itself terminate cortical seizure activity.
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: mechanical ventilation
    term:
      id: NCIT:C70909
      label: Mechanical Ventilation
  target_mechanisms:
  - target: Respiratory depression
    treatment_effect: BYPASSES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Management of TCA poisoning begins with prompt stabilization of the airway, breathing, and circulation.
      explanation: Supports airway and ventilatory assessment as initial resuscitation.
    description: Supports gas exchange when respiratory drive or airway protection is inadequate.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Management of TCA poisoning begins with prompt stabilization of the airway, breathing, and circulation.
    explanation: Supports airway and ventilatory assessment as initial resuscitation.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Careful monitoring of serum pH is essential before endotracheal intubation because peri-intubation respiratory acidosis may occur.
    explanation: Identifies the peri-intubation acid-base risk.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Refractory seizures may require phenobarbital or propofol, typically after endotracheal intubation for airway protection.
    explanation: Supports airway protection in treatment escalation.
  action_category: THERAPEUTIC
- name: Avoidance of potentially harmful antidotes and antiarrhythmics
  description: Physostigmine and flumazenil are generally avoided in TCA toxicity. Class IA, IC and III antiarrhythmics can aggravate toxicity; this caution does not encompass all rhythm treatment, since selected class Ib rescue and torsades-specific care have different roles. Antimuscarinic delirium or hyperthermia should not be described as harmless.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Physostigmine, class IA, IC, and III antiarrhythmic agents, and flumazenil are relatively contraindicated in TCA toxicity.
    explanation: The current synthesis explicitly records the caution.
  action_category: THERAPEUTIC
- name: Toxicology consultation and serial monitoring
  description: Early poison-center or medical-toxicology consultation informs triage and management. Serial clinical assessment, ECG, pH and electrolytes guide treatment and escalation; asymptomatic observation decisions depend on reliable exposure history and clinical context.
  action_category: MONITORING
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Consultation with a medical toxicologist or regional poison center is recommended for all cases of known or suspected TCA poisoning.
    explanation: Supports consultation for suspected as well as confirmed poisoning.
- name: Psychiatric assessment after intentional overdose
  description: After medical stabilization, assess suicide risk and arrange appropriate psychiatric care following intentional ingestion.
  action_category: DIAGNOSTIC
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Psychiatric consultation should be obtained after medical stabilization in cases of intentional overdose to assess suicide risk and guide further treatment.
    explanation: Specifies both timing and purpose.
- name: Medication safety and storage counseling
  description: Counsel on prescribed dosing, medication errors and safe storage out of the reach of children.
  action_category: COUNSELING_INFORMATIONAL
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Preventive counseling should emphasize adherence to prescribed dosing, avoidance of unsupervised dose adjustments, and safe medication storage out of the reach of children.
    explanation: Supports exposure prevention counseling.
  treatment_term:
    preferred_term: Counseling
    term:
      id: NCIT:C61547
      label: Counseling
- name: Torsades-directed resuscitation
  description: Documented torsades de pointes requires rhythm-specific resuscitation, including magnesium where indicated, alongside correction of toxic and electrolyte contributors. A prolonged QT alone is not the same event as torsades.
  action_category: THERAPEUTIC
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Patients who develop torsades de pointes should be managed according to ACLS protocols, and additional magnesium may be administered during cardiopulmonary resuscitation when feasible.
    explanation: Provides torsades-specific management.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: A typical initial dose is 2 g of magnesium sulfate.
    explanation: Identifies the agent; no fixed-dose instruction is inferred for every age or scenario.
  target_mechanisms:
  - target: Torsade de pointes
    treatment_effect: MODULATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
      reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: Patients who develop torsades de pointes should be managed according to ACLS protocols, and additional magnesium may be administered during cardiopulmonary resuscitation when feasible.
      explanation: Provides torsades-specific management.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: magnesium sulfate
      term:
        id: CHEBI:32599
        label: magnesium sulfate
animal_models:
- name: Nortriptyline-infusion swine model of severe tricyclic cardiotoxicity
  species: Domestic swine
  publication: PMID:9737495
  description: Twenty-four swine received intravenous nortriptyline to QRS >120 ms and systolic pressure ≤50 mmHg, then were randomized to saline, bicarbonate, hyperventilation or control. Hypertonic saline improved QRS and pressure most at ten minutes under this protocol, but provided 15 mEq/kg sodium compared with 3 mEq/kg in the bicarbonate arm; this was not an equisodium comparison.
  modeled_mechanisms:
  - target: Slowed His-Purkinje and Myocardial Conduction
    relationship: RECAPITULATES
    fidelity: MODERATE
    model_scale: ORGANISM
    description: 'The model is defined by the conduction defect: animals were dosed until the QRS exceeded 120 ms, and QRS duration is the primary electrocardiographic outcome.'
    limitations: Intravenous exposure in anesthetized animals, short follow-up and unequal sodium doses limit translation and separation of sodium versus alkalinization effects.
    evidence:
    - reference: PMID:9737495
      reference_title: 'Experimental tricyclic antidepressant toxicity: a randomized, controlled comparison of hypertonic saline solution, sodium bicarbonate, and hyperventilation.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: Twenty-four mixed-breed, domestic swine of either sex were given an intravenous infusion of nortriptyline (NT) until development of both a QRS duration longer than 120 ms and a systolic blood pressure (SBP) less than or equal to 50 mm Hg.
      explanation: States the dosing endpoint, which is the conduction defect this link names.
      quote_role: PRIMARY_RESULT
  - target: Circulatory Failure
    relationship: RECAPITULATES
    fidelity: MODERATE
    model_scale: ORGANISM
    description: The same dosing endpoint includes profound hypotension, and systolic pressure after treatment is the model's other primary outcome.
    limitations: Intravenous exposure in anesthetized animals, short follow-up and unequal sodium doses limit translation and separation of sodium versus alkalinization effects.
    evidence:
    - reference: PMID:9737495
      reference_title: 'Experimental tricyclic antidepressant toxicity: a randomized, controlled comparison of hypertonic saline solution, sodium bicarbonate, and hyperventilation.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: The mean SBP 10 minutes after treatment was 54+/-18 mm Hg in the control group, 134+/-21 mm Hg in the HTS group, 85+/-19 mm Hg in the NaHCO3 group, and 60+/-12 mm Hg in the HV group (P<.05).
      explanation: Reports the blood-pressure recovery across arms, which is the circulatory endpoint this link names.
      quote_role: PRIMARY_RESULT
- name: Amitriptyline-infusion swine model of tricyclic-induced hypotension
  species: Domestic swine
  publication: PMID:25377397
  description: Twenty-four female swine with amitriptyline-induced severe hypotension were randomized to lipid emulsion or bicarbonate. ILE did not improve hypotension compared with bicarbonate in this pilot. Survival was poor, and the small protocol-specific comparison does not exclude benefit in every human rescue setting.
  modeled_mechanisms:
  - target: Circulatory Failure
    relationship: RECAPITULATES
    fidelity: MODERATE
    model_scale: ORGANISM
    description: The model is defined by a haemodynamic endpoint and reads out mean arterial pressure and cardiac output continuously.
    limitations: Severe intravenous intoxication in anesthetized swine, small groups and high mortality limit power and generalization to clinical rescue.
    evidence:
    - reference: PMID:25377397
      reference_title: 'Intravenous lipid emulsion therapy does not improve hypotension compared to sodium bicarbonate for tricyclic antidepressant toxicity: a randomized, controlled pilot study in a swine model.'
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: 24 female Sus scrofa swine weighing 45 to 55 kg were infused with amitriptyline at 0.5 mg/kg/min until the MAP reached 60% of baseline values
      explanation: States the haemodynamic endpoint that defines the model.
      quote_role: PRIMARY_RESULT
  evidence:
  - reference: PMID:25377397
    reference_title: 'Intravenous lipid emulsion therapy does not improve hypotension compared to sodium bicarbonate for tricyclic antidepressant toxicity: a randomized, controlled pilot study in a swine model.'
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    snippet: 24 female Sus scrofa swine weighing 45 to 55 kg were infused with amitriptyline at 0.5 mg/kg/min until the MAP reached 60% of baseline values
    explanation: States the species, dose rate and haemodynamic endpoint that define the model, including the 60%-of-baseline figure quoted in its description.
    quote_role: PRIMARY_RESULT
- name: Intraperitoneal amitriptyline rat model of tricyclic cardiotoxicity
  species: Rat
  publication: PMID:25939777
  description: 'Thirty-six female Sprague-Dawley rats were divided into six groups: three received intraperitoneal amitriptyline alone or with simultaneous sodium bicarbonate or hypertonic saline, and three served as saline/bicarbonate/control comparison groups. ECG changes and time to the study death endpoint were followed for 60 minutes. This tests prophylaxis during experimental intoxication, not delayed rescue after oral human overdose.'
  modeled_mechanisms:
  - target: Slowed His-Purkinje and Myocardial Conduction
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: ORGANISM
    description: QRS duration lengthens significantly in every amitriptyline-treated group, so the conduction defect is reproduced.
    limitations: Intraperitoneal exposure, concomitant prophylactic therapy, anesthetic coexposures, 60-minute follow-up and a heart-rate/asystole death endpoint limit translation. Blood pH was not measured, and sodium sampling differed between early deaths and survivors.
    evidence:
    - reference: PMID:25939777
      reference_title: Can empirical hypertonic saline or sodium bicarbonate treatment prevent the development of cardiotoxicity during serious amitriptyline poisoning? Experimental research.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: the amitriptyline-administered groups (groups 1, 2 and 3) showed a statistically significant increase in the QRS duration
      explanation: Reports the conduction defect reproduced in the model.
      quote_role: PRIMARY_RESULT
  evidence:
  - reference: PMID:25939777
    reference_title: Can empirical hypertonic saline or sodium bicarbonate treatment prevent the development of cardiotoxicity during serious amitriptyline poisoning? Experimental research.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    snippet: Amitriptyline was administered at a dose 50 mg/kg i.p. to induce toxicity.
    explanation: States the dosing route and amount that define the model.
    quote_role: PRIMARY_RESULT
- name: Amitriptyline distribution and lipid-infusion pig model
  species: Domestic swine
  publication: PMID:23639060
  description: Twenty anesthetized pigs received intravenous amitriptyline, followed after tissue distribution by randomized lipid emulsion or Ringer acetate. Lipid increased plasma total drug and reduced brain concentration by 25%; the lower heart/plasma ratio does not establish lower absolute cardiac concentration. No severe arrhythmias occurred and hemodynamics did not differ between groups.
  modeled_mechanisms:
  - target: Systemic Tricyclic Antidepressant Burden
    relationship: PERTURBS
    fidelity: MODERATE
    model_scale: ORGANISM
    description: Measures redistribution between plasma and sampled tissues after lipid infusion.
    limitations: Total concentration and tissue/plasma ratios do not measure unbound drug at channel sites or total-body elimination; this model did not reproduce severe arrhythmia.
    evidence:
    - reference: PMID:23639060
      reference_title: Intravenous lipid emulsion entraps amitriptyline into plasma and can lower its brain concentration--an experimental intoxication study in pigs.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      snippet: Lipid emulsion reduced brain amitriptyline concentration by 25% (p = 0.038) and amitriptyline concentration ratios brain/arterial plasma (p = 0.016) and heart/arterial plasma (p = 0.011).
      explanation: Reports distinct concentration and ratio endpoints.
    - reference: PMID:23639060
      reference_title: Intravenous lipid emulsion entraps amitriptyline into plasma and can lower its brain concentration--an experimental intoxication study in pigs.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      quote_role: PRIMARY_RESULT
      snippet: There were no differences in ECG parameters and no severe cardiac arrhythmias occurred.
      explanation: Defines the model’s cardiac limit.
diagnosis:
- name: Exposure history and clinical assessment
  description: Establish the drug, estimated amount, formulation, timing, coingestants and relevant cardiac or seizure history. An antimuscarinic toxidrome is suggestive but is shared with other poisons and can be incomplete.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: When TCA toxicity is suspected, the history should include the specific drug ingested, estimated dose, formulation, time of ingestion, and any coingestants, including prescription, over-the-counter, and herbal products.
    explanation: Specifies the necessary exposure history.
  - reference: PMID:10452441
    reference_title: ECG abnormalities in tricyclic antidepressant ingestion.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: the presence or absence of features of the TCA toxidrome are not sufficient to detect or exclude toxicity from this class of drugs
    explanation: Neither the presence nor absence of the toxidrome is a definitive diagnostic test.
- name: Serial 12-lead electrocardiography
  description: Obtain an early ECG and follow QRS duration, rhythm, QT and the terminal aVR vector with the clinical course. Historical QRS and aVR associations aid risk assessment but cannot independently rule in or rule out serious toxicity. ECG findings are not unique to TCAs.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: An ECG should be obtained early in the evaluation of suspected TCA overdose.
    explanation: Supports early ECG assessment.
  - reference: PMID:4022081
    reference_title: Value of the QRS duration versus the serum drug level in predicting seizures and ventricular arrhythmias after an acute overdose of tricyclic antidepressants.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: Seizures occurred at any QRS duration of 0.10 second or longer (P less than 0.05), but ventricular arrhythmias were seen only with a QRS duration of 0.16 second or longer (P less than 0.0005).
    explanation: The thresholds are observed cohort associations, not deterministic boundaries.
    quote_role: PRIMARY_RESULT
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: An R/S ratio of 0.7 or greater in lead aVR or an R wave greater than 3 mm in lead aVR is strongly associated with both seizures and arrhythmias.
    explanation: The chapter summarizes aVR risk associations; these are not definitive diagnostic cutoffs.
  - reference: PMID:10452441
    reference_title: ECG abnormalities in tricyclic antidepressant ingestion.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The ECG can neither unequivocally rule in nor rule out impending toxicity
    explanation: Explicitly limits the standalone predictive ability of the ECG.
  - reference: PMID:7904010
    reference_title: Greater toxicity in overdose of dothiepin than of other tricyclic antidepressants.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: Patients with only minor sedation and normal limb-lead QRS width may still have major complications.
    explanation: A normal initial QRS and mild sedation did not exclude serious complications in this cohort.
    quote_role: PRIMARY_RESULT
- name: Laboratory assessment and coingestant evaluation
  description: Assess glucose, acid-base status and electrolytes, and evaluate possible acetaminophen, salicylate or other coingestants. Serum TCA measurements can support an uncertain exposure history but do not reliably quantify severity or replace clinical monitoring.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Standard laboratory evaluation should include assessment for potential coingestants, such as acetaminophen and aspirin.
    explanation: Supports coingestant testing.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Serum TCA concentrations do not reliably correlate with toxicity severity and are not always clinically available, although measurement may help confirm an unknown overdose when clinical findings suggest TCA ingestion.
    explanation: Separates exposure confirmation from severity prediction.
  - reference: PMID:3537621
    reference_title: Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: There must be regular monitoring for hypoxia, acidosis and hypokalaemia
    explanation: Supports repeated assessment of acidosis, hypoxia and potassium.
references:
- reference: PMID:16390222
  title: 'Tricyclic antidepressant poisoning : cardiovascular toxicity.'
- reference: PMID:16390221
  title: 'Management of the cardiovascular complications of tricyclic antidepressant poisoning : role of sodium bicarbonate.'
- reference: PMID:17453872
  title: 'Tricyclic antidepressant poisoning: an evidence-based consensus guideline for out-of-hospital management.'
- reference: url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
  title: https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
- reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
  title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
  tags:
  - StatPearls
- reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK425165/
  title: Amitriptyline Therapy and CYP2D6 and CYP2C19 Genotype - Medical Genetics Summaries - NCBI Bookshelf
- reference: PMID:35088415
  title: Tricyclic antipsychotics and antidepressants can inhibit α5-containing GABA(A) receptors by two distinct mechanisms.
- reference: PMID:41122889
  title: 'Part 10: Adult and Pediatric Special Circumstances of Resuscitation: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.'
notes: "Comprehensive review consumed the available scientific full bodies and tables for the clinical series, comparative toxicity study, ECMO report, rat experiments and recovered hERG/GABAA studies, together with all remaining cited abstracts. The full 2007 consensus guideline, current StatPearls chapter and amitriptyline pharmacogenetic chapter were read. The 2007 document addresses US poison-center out-of-hospital triage for specified TCAs and is not a complete hospital guideline; its asymptomatic six-hour recommendation applies to unintentional exposure, not self-harm. The 2025 AHA sodium-channel-poisoning recommendations were checked on the primary guideline website; automated full-body retrieval was blocked, so the cached PMID supplies bibliographic context while quoted care claims use available full clinical sources. No applicable GeneReviews chapter was identified.\nSelected cohort counts and experimental endpoints are retained without assigning disease-wide frequencies. The recent 75-patient tertiary-center series has exclusions and frequent prior treatment, and its poor-outcome group combines deaths with discharge against medical advice; it is not a mortality denominator.\
  \ The historical toxicity indices are comparative ratios from differently sampled datasets, not percentages.\nThe causal graph separates phase 0 depolarization from repolarization and allows acidosis to amplify toxicity. Molecular actions and experimental current measurements do not establish that every downstream clinical manifestation is mediated by one receptor. GABAA inhibition is subtype- and compound-dependent, with clinical contribution unresolved.\nThe pharmacogenetic chapter concerns therapeutic prescribing and plasma exposure. CYP2D6/CYP2C19 guidance is not a validated method for forecasting acute-overdose outcomes. No disease-specific interventional trial outcome is inferred from animal sodium, lipid or ventilation experiments."
progression:
- phase: Early presentation
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: The manifestations of toxicity usually become apparent within 2 hours of ingestion.
    explanation: Supports the usual early onset without making it a universal exclusion window.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: TCA poisoning produces anticholinergic effects that slow gastrointestinal motility, delaying absorption and peak drug concentrations.
    explanation: Identifies delayed absorption as a toxicokinetic contributor.
  notes: Clinical manifestations often develop within two hours, but antimuscarinic slowing of gastrointestinal transit and coingestants can delay absorption. Initial antimuscarinic or neurological findings can precede abrupt severe cardiotoxicity.
- phase: Severe toxicity and recovery
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Toxicity usually lasts 24 to 48 hours but is highly dose-dependent.
    explanation: Provides a typical course rather than a promised recovery time.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: Patients with signs of toxicity generally require hospital admission until sustained clinical improvement occurs.
    explanation: Supports admission for clinically apparent toxicity.
  notes: Seizures, depressed consciousness, dysrhythmias and hemodynamic instability require hospital care and repeated assessment. Toxicity often lasts 24–48 hours but varies with exposure; severe or prolonged courses occur. An asymptomatic observation window must be interpreted in the context of ECG findings, exposure history and poison-center assessment, particularly after self-harm.
experimental_models:
- name: Isolated cardiac Purkinje fibers exposed to amitriptyline
  experimental_model_type: OTHER
  publication: PMID:6092616
  description: Amitriptyline-exposed Purkinje fibers were superfused with high sodium, high bicarbonate or high-pH/low-CO2 solutions to separate components of phase 0 recovery.
  modeled_mechanisms:
  - target: Slowed Cardiac Phase 0 Depolarization
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: Amitriptyline-exposed Purkinje fibers were superfused with high sodium, high bicarbonate or high-pH/low-CO2 solutions to separate components of phase 0 recovery.
    limitations: An isolated electrophysiological preparation lacks systemic pharmacokinetics and clinical outcomes; action-potential duration shortened in this experiment.
    evidence:
    - reference: PMID:6092616
      reference_title: Mechanism of reversal of toxic effects of amitriptyline on cardiac Purkinje fibers by sodium bicarbonate.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: Amitriptyline significantly depressed action potential amplitude and Vmax without altering resting membrane potential and abbreviated action potential duration at all phases of repolarization.
      explanation: Measures the phase 0 defect in isolated fibers. Action-potential duration shortened in this preparation, so these results do not support a universal repolarization-prolongation step.
    - reference: PMID:6092616
      reference_title: Mechanism of reversal of toxic effects of amitriptyline on cardiac Purkinje fibers by sodium bicarbonate.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: The results suggest that the beneficial effects of NaHCO3 are related to a reversal of drug effects on phase 0 characteristics and that this effect is due both to alkalinization and to increases in extracellular Na concentration.
      explanation: The isolated-fiber experiments support contributions from both sodium and pH; they do not establish complete reversal or one dominant clinical mechanism.
- name: hERG-expressing CHO cells
  experimental_model_type: CELL_LINE
  publication: PMID:10510461
  description: Transiently transfected CHO cells underwent voltage-clamp recording during imipramine or amitriptyline exposure. Current inhibition was reversible; detailed imipramine kinetics suggested both closed- and open-state components without direct structural binding evidence.
  modeled_mechanisms:
  - target: hERG Potassium Channel Blockade
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: Transiently transfected CHO cells underwent voltage-clamp recording during imipramine or amitriptyline exposure. Current inhibition was reversible; detailed imipramine kinetics suggested both closed- and open-state components without direct structural binding evidence.
    limitations: Cloned-channel inhibition does not reproduce a whole cardiac action potential or measure clinical free-drug concentrations. Drug, voltage protocol and expression-system conditions affect kinetics.
    evidence:
    - reference: PMID:10510461
      reference_title: Inhibition of the current of heterologously expressed HERG potassium channels by imipramine and amitriptyline.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: HERG-encoded potassium channels were inhibited in a reversible manner by both imipramine and amitriptyline.
      explanation: Demonstrates inhibition in transfected CHO cells, not a patient-level channel assay.
- name: hERG-expressing oocytes and isolated rat atrial myocytes
  experimental_model_type: OTHER
  publication: PMID:10742304
  description: Amitriptyline concentration-, voltage- and use-dependent effects were studied in hERG-expressing Xenopus oocytes; a separate isolated-rat-atrial-cell assay measured native IKr inhibition.
  modeled_mechanisms:
  - target: hERG Potassium Channel Blockade
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: Amitriptyline concentration-, voltage- and use-dependent effects were studied in hERG-expressing Xenopus oocytes; a separate isolated-rat-atrial-cell assay measured native IKr inhibition.
    limitations: The two experimental systems differ from human ventricular tissue, and the measurements do not establish clinical frequency or severity of torsades.
    evidence:
    - reference: PMID:10742304
      reference_title: Blockade of the HERG human cardiac K(+) channel by the antidepressant drug amitriptyline.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      snippet: In rat atrial myocytes bathed in 35 degrees C, 5 microM amitriptyline blocked I(Kr) by 55%.
      explanation: Documents the native IKr assay, distinct from the oocyte expression system.
      quote_role: PRIMARY_RESULT
- name: Rat cortical GABA-stimulated chloride-uptake preparations
  experimental_model_type: OTHER
  publication: PMID:2456440
  description: Rat cerebral cortical vesicles showed reduced GABA-stimulated chloride uptake during selected antidepressant exposure. A later Schild analysis included amitriptyline and did not support pure competitive GABA antagonism.
  modeled_mechanisms:
  - target: Reduced GABAA Receptor Current
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: Rat cerebral cortical vesicles showed reduced GABA-stimulated chloride uptake during selected antidepressant exposure. A later Schild analysis included amitriptyline and did not support pure competitive GABA antagonism.
    limitations: Ex vivo uptake and binding analyses do not demonstrate that this mechanism is necessary or sufficient for seizures in poisoned humans.
    evidence:
    - reference: PMID:2456440
      reference_title: Antidepressants and seizure-interactions at the GABA-receptor chloride-ionophore complex.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: Using the method of GABA-stimulated 36Cl-uptake by rat cerebral cortical vesicles, we show that some antidepressant drugs (imipramine, amitryptyline, and mianserine) can inhibit the GABA-receptor chloride uptake
      explanation: Demonstrates inhibition in rat cortical vesicles; the source spells the drug names this way.
    - reference: PMID:9691231
      reference_title: Schild regression analysis of antidepressant and bicuculline antagonist effects at the GABAA receptor.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: It is concluded that neither the antidepressants studied nor bicuculline are pure competitive GABA antagonists at the GABAA receptor-chloride-ionophore complex in the rat cerebral cortex.
      explanation: Constrains a claim of simple competitive antagonism for the tested antidepressants.
- name: Recombinant GABAA subtype assays in Xenopus oocytes
  experimental_model_type: OTHER
  publication: PMID:35088415
  description: Two-electrode voltage clamp compared drug effects in recombinant receptor combinations. At 100 μM, imipramine and nortriptyline inhibited α5β3γ2 currents but lacked significant inhibition at the tested α1β3γ2 subtype. Mutational effects suggest a putative allosteric pocket, not a structurally proven binding pose.
  modeled_mechanisms:
  - target: Reduced GABAA Receptor Current
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: Two-electrode voltage clamp compared drug effects in recombinant receptor combinations. At 100 μM, imipramine and nortriptyline inhibited α5β3γ2 currents but lacked significant inhibition at the tested α1β3γ2 subtype. Mutational effects suggest a putative allosteric pocket, not a structurally proven binding pose.
    limitations: The study focused largely on antipsychotic pharmacology, used recombinant receptors and did not assay TCA-poisoned patients or seizures. Antipsychotic orthosteric-binding results cannot be assigned to TCAs.
    evidence:
    - reference: PMID:35088415
      reference_title: Tricyclic antipsychotics and antidepressants can inhibit α5-containing GABA(A) receptors by two distinct mechanisms.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: All of them diminished GABA‐elicited currents in α5β3γ2 receptors
      explanation: Includes imipramine and nortriptyline in recombinant oocytes; this does not demonstrate clinical seizure mediation.
    - reference: PMID:35088415
      reference_title: Tricyclic antipsychotics and antidepressants can inhibit α5-containing GABA(A) receptors by two distinct mechanisms.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      quote_role: PRIMARY_RESULT
      snippet: The chlorpromazine‐ levomepromazine‐ imipramine‐ nortriptyline group had no significant effects on the α1β3γ2 receptors at 100 μM.
      explanation: The negative comparator constrains generalization of the subtype-specific current inhibition.
differential_diagnoses:
- name: Other antimuscarinic drug poisoning
  description: Antihistamines, antipsychotics, cyclobenzaprine and tropane alkaloids can produce overlapping antimuscarinic findings. Exposure history and the complete clinical course are essential; several alternative agents can also cause cardiac toxicity.
  distinguishing_features:
  - A toxidrome alone cannot identify the drug; establish the exposure and assess coingestants.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: Initial manifestations often resemble those of an anticholinergic toxidrome caused by antihistamines, such as diphenhydramine and chlorpheniramine
    explanation: The chapter describes overlapping clinical presentations.
- name: Other cardiotoxic drug poisoning
  description: Class I antiarrhythmics and other cardiotoxic agents can mimic the ECG and circulatory findings of TCA poisoning.
  distinguishing_features:
  - Medication and exposure history help distinguish the cause; QRS widening is not specific to TCAs.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: Cardiotoxic agents can produce ECG abnormalities that mimic those of TCA poisoning.
    explanation: Explicitly identifies the ECG differential.
- name: Hypoglycemia and other metabolic encephalopathies
  description: Metabolic disorders can cause altered mental status or seizures and may coexist with poisoning.
  distinguishing_features:
  - Check glucose and relevant metabolic studies while stabilizing the patient.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
    reference_title: Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: Metabolic disorders may likewise cause altered mental status. Potential etiologies include hypoglycemia, hyperglycemia, hyponatremia, hypernatremia, hepatic encephalopathy, uremic encephalopathy, and thyroid storm.
    explanation: Supports the metabolic differential and glucose assessment.
📚

References & Deep Research

References

8
PMID:16390222
Tricyclic antidepressant poisoning : cardiovascular toxicity.
No top-level findings curated for this source.
PMID:16390221
Management of the cardiovascular complications of tricyclic antidepressant poisoning : role of sodium bicarbonate.
No top-level findings curated for this source.
PMID:17453872
Tricyclic antidepressant poisoning: an evidence-based consensus guideline for out-of-hospital management.
No top-level findings curated for this source.
url:https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
https://www.clintox.org/wp-content/uploads/2016/05/Tricyclic-antidepressant-poisoning.pdf
No top-level findings curated for this source.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK430931/
Tricyclic Antidepressant Toxicity - StatPearls - NCBI Bookshelf
No top-level findings curated for this source.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK425165/
Amitriptyline Therapy and CYP2D6 and CYP2C19 Genotype - Medical Genetics Summaries - NCBI Bookshelf
No top-level findings curated for this source.
PMID:35088415
Tricyclic antipsychotics and antidepressants can inhibit α5-containing GABA(A) receptors by two distinct mechanisms.
No top-level findings curated for this source.
PMID:41122889
Part 10: Adult and Pediatric Special Circumstances of Resuscitation: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
No top-level findings curated for this source.

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (2)

Review acute tricyclic antidepressant poisoning against full clinical and experimental sources · 2026-09-21T07:08:01Z · View source

Reviewed the full entry, matching deep-research output, all 32 originally cited PMID records and every available substantive full body and table. Recovered the full 2007 poison-center consensus, current StatPearls chapter, amitriptyline pharmacogenetic chapter, canonical hERG full text and subtype-specific GABAA experiments through the sanctioned fetcher. Split depolarization from repolarization; qualified indirect myocardial, seizure and pharmacokinetic mechanisms; corrected parent/metabolite, cohort-frequency, ECG-threshold and shock-scope claims. Added documented antimuscarinic, neurological and pulmonary findings, care/diagnostic gaps and experimental models with assay and clinical limits. An independent bounded care-source audit informed treatment revisions. Read the 2025 AHA sodium-channel section on its primary website; official automated full-body routes were blocked, so retained bibliographic context and exact care quotations from available sources without fabricating a cache. No applicable GeneReviews chapter. Full-text recovery changes are separately tested provider code; reference caches are generated, never hand-edited. Schema, live terms and 208/208 snippets passed before final formatting; remaining repository gates and final peer integration check are tracked separately. Final care/diagnosis integration audit found no material residual error; its full-sentence vasopressor quotation refinement was incorporated. All 25 repository guards and node-class integrity passed; final post-format authoritative validation remains tracked in the validation log. A separate independent integration audit read all 20 nodes and all nine models and found no blocking topology or model-scope conflation. Final live HPO definition/synonym inspection confirmed Hyperthermia is an EXACT synonym of HP:0001945 Fever; that specific binding replaces the provisional temperature-regulation parent. Added source-backed differential diagnoses and magnesium agent mapping. Final authoritative schema/live-ontology validation and 212/212 cached snippets passed, including the added differentials. The published NCIT magnesium label was outside the agent enum, so the validated CHEBI:32599 magnesium sulfate binding was used. The unsupported monitoring-action binding was omitted; counseling uses the validated action. The discarded unused NCIT lookup row was restored to the prior generated cache.

Create: Acute Tricyclic Antidepressant Poisoning (MONDO:0018547) · 2026-09-20T21:06:31Z · View source

New entry for acute tricyclic antidepressant poisoning, bound to MONDO:0018547. Duplicate preflight was run across all three surfaces before starting - origin/main by MONDO ID and label, PRs in all states, issues in all states - and returned nothing. Deep research: falcon was requested and is not configured in this environment, so the run used --fallback and the report records fell_back: true, requested_provider: falcon. just preflight-dr returns SKIP, because MONDO records no causal gene for a poisoning and the gene-identity check cannot discriminate; the manual fallback check passes (the report's top genes are CYP2D6, CYP2C19, SCN5A, KCNH2). The report's own validation reports quotes_valid 2 of 9 checked and needs_review true, so no text was taken from it - it contributed four PMIDs (17453872, 9737495, 25939777, 33655968) and nothing else. Its ontology suggestions were checked and rejected: HP:0000615 offered as Mydriasis is Abnormal pupil morphology, HP:0002593 offered as Ileus is Intestinal lymphangiectasia, and NCIT:C1636 offered as Activated Charcoal is Therapeutic Steroid Hormone. Every CURIE in the entry was resolved from a live OAK lookup instead. Content: 17 pathophysiology nodes modelling five parallel molecular arms off one exposure node (cardiac fast sodium channel, hERG potassium channel, vascular alpha-1, muscarinic, monoamine transporter) plus a CNS arm; 18 phenotypes, all 18 causally connected; 11 treatments; 3 animal models linked to the pathograph via modeled_mechanisms; 32 distinct references; 140 evidence items, all snippet-verified against the committed cache. Three nodes declare conforms_to against kb/modules/xenobiotic_cardiac_channel_perturbation.yaml - both channel-blockade nodes to its trigger node and Altered Cardiac Action Potential to its key conformance target. Nothing downstream conforms, because the module's working-myocardium branch is afterdepolarization-driven triggered activity whereas this poisoning's ventricular arrhythmia is reentrant on a slow-conduction substrate. The pathograph contains one deliberate cycle: Systemic Acidaemia feeds back onto Cardiac Fast Sodium Channel Blockade, because acidaemia raises the ionized drug fraction that binds the channel. That loop is the reason deterioration is abrupt and it is what sodium bicarbonate is given to break. An adversarial pre-PR review with fresh context produced 22 findings, of which 21 were taken. The substantive ones: HP:0001942 Metabolic acidosis was rebound to its parent HP:0001941 Acidosis, because HPO defines metabolic acidosis as excluding a respiratory cause and the cited sources say only acidosis; GO:0098903 was replaced by GO:0098915, which names ventricular repolarization rather than its regulation; two explanations were rewritten where the quoted sentence did not say what the explanation claimed (a PMID:9377889 quote about resolution time cited for a QRS claim, and a PMID:17453872 quote about emesis cited as the guideline's charcoal position - the latter replaced by the guideline's actual charcoal recommendation, which is unfavourable and is now graded REFUTE); a miscount of REFUTE items in a treatment note was corrected; the VA-ECMO case count was scoped to its source review's November 2020 search date; and the physostigmine agent binding, documented as an unrun search, was researched and filled (NCIT:C81336). Prose claiming that seizures and hypoventilation generate the acidaemia was removed from four places, because no cited source states either and the graph models only the circulatory route. Validation: just validate-disorders passes with all snippets verified; check-entity-refs, check-causal-targets, check-duplicate-keys, check-enum-values, check-qualifier-terms, check-snippet-grading, check-title-snippets, check-snippet-length, check-folded-hyphens, check-environmental-evidence, check-case-collisions, check-not4curation, check-reference-titles and check-delivery-system are all clean; list-disconnected-phenotypes reports 18/18 connected; list-gene-term-mismatches reports 8 of 8 gene bindings naming the gene the entry names; prose-figure-audit reports no unsupported figure; check-genereviews returns NO_CHAPTER for GeneReviews and TAGGED for the StatPearls chapter it found. Cache changes are additive only.

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Acute Tricyclic Antidepressant (TCA) Poisoning — Comprehensive Research Report
claude-haiku-4-5-20251001, claude-sonnet-5 37 citations 2026-09-20T19:52:57.275696

Acute Tricyclic Antidepressant (TCA) Poisoning — Comprehensive Research Report

1. Disease Information

Overview. Acute tricyclic antidepressant poisoning is a potentially lethal toxidrome resulting from single large-dose ingestion (almost always intentional/suicidal) of a tricyclic antidepressant. It is characterized by the triad of (1) an anticholinergic toxidrome (mydriasis, dry mucous membranes, tachycardia, urinary retention, ileus, hyperthermia), (2) central nervous system toxicity (agitation progressing to lethargy, coma, and seizures), and (3) cardiovascular toxicity (sodium-channel-mediated conduction delay/QRS widening, hypotension, and ventricular dysrhythmias), which is the principal cause of death StatPearls NBK430931; PMC8439401.

Key identifiers: - MONDO: MONDO:0018547 (Acute tricyclic antidepressant poisoning) — NORD/MONDO page - Orphanet: ORPHA:43117 — Orphanet record - ICD-10: T43.0 (Poisoning by tricyclic and tetracyclic antidepressants); ICD-9: 969.0 - eMedicine/Medscape ID: 819204 — Tricyclic Antidepressant Toxicity, Medscape - Representative specific drugs, each with its own identifiers used in curation (HGNC targets are the transporters/receptors, not the drugs; CHEBI covers the small molecules): amitriptyline, nortriptyline, imipramine, desipramine, doxepin, clomipramine, trimipramine, protriptyline, amoxapine, dothiepin (dosulepin), maprotiline (a "tetracyclic" grouped clinically with TCAs).

Synonyms: cyclic antidepressant overdose/poisoning, tricyclic antidepressant (TCA) toxicity, TCA overdose.

Data provenance note. Most quantitative information below is derived from aggregated poison-control/registry data (NPDS/AAPCC annual reports) and retrospective single- or multi-center case series, i.e., disease-level/aggregate resources rather than individual EHR record review — an important distinction for evidence grading in the knowledge base.

2. Etiology

Primary cause. TCA poisoning is essentially always iatrogenic/pharmacologic overdose — an exposure (nearly always a deliberate self-poisoning) to a prescribed or otherwise available tricyclic antidepressant. There is no intrinsic "genetic disease" etiology; the entity is a toxicologic/pharmacologic acute poisoning, so its "genetic risk factors" operate through pharmacogenomic modulation of drug exposure/toxicity rather than causing the disease de novo.

Risk factors

Genetic (pharmacogenomic) risk factors — modulate individual susceptibility to toxicity at a given dose, not causal in the Mendelian sense: - CYP2D6 poor metabolizer status. Amitriptyline and most TCAs undergo demethylation (largely CYP2C19-mediated, producing active secondary-amine metabolites such as nortriptyline from amitriptyline) and hydroxylation (largely CYP2D6-mediated, producing less active hydroxylated metabolites). "Amitriptyline is metabolized mainly via CYP2C19 and CYP2D6 pathways. Metabolism by CYP2C19 results in active metabolites, including nortriptyline… while metabolism catalyzed by CYP2D6 results in the formation of the less active 10-hydroxy metabolite" CPIC TCA Guideline PDF; NBK425165. CYP2D6 poor metabolizers accumulate higher parent-drug and active-metabolite concentrations at a given dose, raising the risk of supratherapeutic/toxic exposure and QT prolongation; CPIC recommends a ~50% dose reduction for CYP2D6 poor metabolizers and use of an alternative agent in CYP2D6 ultrarapid metabolizers. - CYP2C19 poor metabolizer status similarly raises tertiary-amine (parent drug) concentrations. - At toxic (supratherapeutic) concentrations, CYP2D6's fractional contribution to clearance falls relative to therapeutic concentrations (saturable, capacity-limited metabolism), which is itself a mechanism amplifying toxicity in overdose independent of genotype — "the contribution of CYP2D6 significantly decreased for its demethylation and hydroxylation pathways" as amitriptyline concentration rose from therapeutic to toxic levels (Springer/Forensic Toxicology 2008). - No specific cardiac ion-channel germline variant (e.g., latent Brugada-syndrome SCN5A loss-of-function alleles) has been systematically implicated in TCA poisoning per se, but mechanistically a patient with subclinical SCN5A-related sodium-channelopathy would be expected to be at increased risk of TCA-induced conduction block/Brugada phenocopy given the shared final pathway (see Mechanism, below), based on the shared molecular target rather than direct epidemiologic data.

Environmental / behavioral risk factors: - Access to a lethal quantity of the drug — the single most important modifiable risk factor; large-quantity, non-blister-packaged prescriptions are more lethal in a single ingestion. - Female sex — TCA exposures are more common in women, reflecting a higher rate of self-poisoning attempts in women generally, although completed-suicide-by-any-method rates are higher in men (Medscape epidemiology). - Underlying psychiatric illness (major depressive disorder, especially treatment-resistant depression for which TCAs remain prescribed) is the population from which most exposures arise. - Co-ingestion with other CNS depressants (benzodiazepines) or cardiotoxic agents; in the 6-year retrospective ED series, benzodiazepines (8.0%) and antihypertensives (4.0%) were the most common co-ingestants (PMC13458188). - Delayed presentation / delayed decontamination and pre-existing cardiac conduction disease increase risk of cardiotoxic complications.

Protective factors: - Prescribing pattern shift away from TCAs toward SSRIs/SNRIs has been the dominant population-level protective factor: "The frequency of TCA overdoses has declined since the 1980s, whereas SSRI overdoses have increased significantly, reflecting changes in prescribing practices" (Medscape). - Limiting dispensed quantity / packaging controls — proposed as a means-restriction suicide-prevention strategy: "If pills were packaged in blister packs of 16 to 25, anyone who wanted to use them to commit suicide would have to work really hard… If we make it hard to buy pills in bottles of 50 or 100 capsules that can easily be dumped out and swallowed, we can prevent many deaths" (NCL commentary). No specific jurisdictional statute mandating TCA blister-packaging was identified in this search (unlike the UK's 1998 paracetamol pack-size legislation, which is the model example); this remains a policy proposal rather than an established intervention specific to TCAs. - Rapid access to emergency care / early sodium bicarbonate therapy is protective against progression to lethal dysrhythmia (see Treatment).

Gene–environment interaction: The clearest interaction is pharmacogenomic — CYP2D6/CYP2C19 genotype determines steady-state drug/metabolite exposure at a given prescribed dose (environment = prescribed dose), so a poor-metabolizer genotype converts an otherwise "therapeutic" prescribed dose into a de facto higher effective exposure, and in the overdose setting further shifts an already massive ingested dose toward even higher peak free-drug levels because of saturable first-pass and hepatic clearance (CPIC Guideline).

3. Phenotypes

TCA poisoning phenotypes cluster into three overlapping domains — anticholinergic, neurologic/CNS, and cardiovascular — with onset generally rapid (most severe toxicity manifests within the first 6 hours, and clinical deterioration can be abrupt) (StatPearls NBK430931; ED retrospective series, PMC13458188).

Phenotype Type Suggested HP term Onset/Frequency/Notes
Mydriasis Clinical sign HP:0000615 (Mydriasis) Early anticholinergic sign
Dry mucous membranes / dry mouth Clinical sign HP:0000217 (Xerostomia) Early anticholinergic sign
Tachycardia Clinical sign HP:0001649 (Tachycardia) Very common; 37.3% tachycardic on presentation in one series
Urinary retention Clinical sign HP:0000016 (Urinary retention) Anticholinergic
Decreased/absent bowel sounds (ileus) Clinical sign HP:0002593 (Ileus) Anticholinergic
Hyperthermia Clinical sign HP:0001945 (Fever/hyperthermia) Anticholinergic; worsened by seizures/agitation
Altered mental status / delirium Behavioral/CNS HP:0000738 (Behavioral abnormality) / HP:0031466 (Delirium, if used) 46.7% presented with altered mental status
Drowsiness/lethargy progressing to coma CNS HP:0001262 (Lethargy); HP:0001259 (Coma) Progressive with dose; 29.3% drowsy at presentation
Seizures CNS / neurologic sign HP:0001250 (Seizure) Occur in ~10–20% of significant ingestions; usually brief but may be refractory; predicted by QRS >100 ms
Myoclonic jerks CNS HP:0002379 (Myoclonus) Reported in severe toxicity
Respiratory depression Clinical sign HP:0002093 (Respiratory insufficiency) May require intubation (20% intubated in one ED series)
QRS widening (>100 ms) Lab/ECG abnormality (ECG finding; no dedicated HP term — use as biochemical/EKG readout) Predicts seizures; sodium-channel blockade signature
QRS >160 ms Lab/ECG abnormality — Predicts ventricular dysrhythmias
Terminal R wave in aVR ≥3 mm Lab/ECG abnormality — Sensitivity 81%, specificity 73% for seizures/arrhythmias (Liebelt 1995)
QTc prolongation Lab/ECG abnormality HP:0011675 (Arrhythmia, generic) or specific QT term if modeled Via potassium (hERG) channel blockade
Ventricular tachycardia / ventricular fibrillation Clinical sign HP:0004756 (Ventricular tachycardia) / HP:0001663 (Ventricular fibrillation) Major cause of death
Torsades de pointes Clinical sign HP:0004756 (subsumed) Secondary to QT prolongation
Hypotension Clinical sign HP:0002615 (Hypotension) Alpha-1 blockade + myocardial depression; ~8% hypotensive at presentation
Cardiac arrest / asystole Clinical sign HP:0001695 (Cardiac arrest) End-stage; managed with prolonged CPR/ECMO
Rhabdomyolysis Laboratory abnormality HP:0003201 (Rhabdomyolysis) Rare; secondary to seizures/agitation/hyperthermia
Brugada-phenocopy ECG pattern Lab/ECG abnormality HP:0200110 (Brugada syndrome, ECG pattern - use with caution as "phenocopy" not true channelopathy) Reversible sodium-channel-blockade phenomenon

Age of onset: Not applicable in the congenital sense; this is an acquired acute poisoning, most common in adolescents/adults (mean age ~30–35 years in cohort studies) (Liebelt 1995; PMC13458188).

Severity and progression: Variable and dose-dependent; can range from mild anticholinergic symptoms to death within hours. "All fatal ingestions developed major signs of toxicity mandating admission within two hours of arrival at the hospital, with a mean time from arrival to death of only 5.43 hours, and all patients who died did so within 24 hours of arrival" (classic epidemiologic study, cited via Medscape epidemiology summary). Course is typically monophasic/self-limited over 24–72 hours if the patient survives the acute cardiotoxic window, in contrast to a chronic/progressive disease.

Quality of life impact: Not chronic; QoL impact is acute (ICU stay, intubation, cardiac arrest sequelae, potential anoxic brain injury) rather than long-term unless anoxic injury or prolonged arrest occurs (e.g., the VA-ECMO case discharged without neurological impairment after 27 hours of ECMO support — PMC7939188 — versus cases with post-arrest encephalopathy after prolonged arrest, not separately quantified in these sources).

4. Genetic/Molecular Information

There is no causal Mendelian gene for this acquired poisoning; the "genetic" contribution is entirely pharmacogenomic, governing drug/metabolite exposure rather than an intrinsic disease process.

  • Metabolizing enzymes (modifier genes, not causal genes):
  • CYP2D6 (HGNC:2625) — hydroxylation pathway (inactivation); poor-metabolizer alleles (3, 4, 5, 6, etc.) elevate exposure; CPIC recommends dose reduction in PMs.
  • CYP2C19 (HGNC:2621) — demethylation pathway (tertiary→secondary amine, e.g., amitriptyline→nortriptyline, an active metabolite); poor-metabolizer alleles elevate tertiary-amine parent-drug levels.
  • OCT1 (SLC22A1) — has been studied for effects on amitriptyline pharmacokinetics in combination with CYP2D6/CYP2C19 genotype (Frontiers in Pharmacology 2021).
  • Molecular targets of toxicity (not variants, but the drug-target proteins whose blockade constitutes the mechanism — useful for genetic/biological_processes binding in a mechanism-oriented KB entry):
  • Cardiac voltage-gated sodium channel SCN5A/Nav1.5 — fast inward sodium current, phase-0 depolarization target of TCA blockade (a "sodium channel blocker" class effect analogous to Class IA antiarrhythmics).
  • Cardiac potassium channels (hERG/KCNH2) — TCA blockade of the delayed rectifier potassium current slows phase-3 repolarization, prolonging QT/QTc.
  • GABA-A receptor (multiple GABRA/GABRB/GABRG subunits) — TCAs act at (or near) the picrotoxin site as GABA-A antagonists, contributing to seizures; "tricyclic antidepressants can inhibit α5-containing GABAA receptors by two distinct mechanisms" (PMC9314015).
  • Muscarinic acetylcholine receptors (CHRM1–5) — central and peripheral antagonism producing the anticholinergic toxidrome.
  • Alpha-1 adrenergic receptor (ADRA1A/B/D) — peripheral antagonism producing vasodilation/hypotension.
  • Norepinephrine and serotonin transporters (SLC6A2/NET, SLC6A4/SERT) — the therapeutic monoamine-reuptake-inhibition target; in overdose, initial NET blockade produces a transient hyperadrenergic phase, followed by catecholamine depletion and hypotension.
  • Pathogenic variant classification: Not applicable (acquired poisoning, not a variant-driven disease). No ClinVar/gnomAD relevance beyond the pharmacogenes above.
  • Epigenetics / chromosomal abnormalities: No established role.

5. Environmental Information

  • Primary "environmental" factor is the drug itself — this is fundamentally a xenobiotic (pharmaceutical) exposure. Relevant exposure ontology framing: exposure to a tricyclic antidepressant drug, typically via oral ingestion, in supratherapeutic/toxic quantity.
  • Lifestyle factors: Underlying depressive illness and access to lethal means (large prescribed quantities, unsecured medication) are the dominant modifiable contextual factors; co-ingested ethanol or other CNS depressants worsen CNS/respiratory depression.
  • Infectious agents: Not applicable — this is a toxicologic, not infectious, disease.
  • Occupational/toxin exposures: Not applicable beyond therapeutic/illicit drug access; no industrial or environmental-toxin route of TCA exposure is described in the literature reviewed.

6. Mechanism / Pathophysiology

Ordered causal chain

  1. Ingestion of a supratherapeutic dose of a tricyclic antidepressant → rapid gastrointestinal absorption (further slowed anticholinergic gut motility can paradoxically prolong absorption) → high peak plasma and myocardial tissue concentrations, driven by the drugs' large volume of distribution and high (~90–95%) plasma protein binding (chiefly to α1-acid glycoprotein).
  2. Supratherapeutic TCA binds and blocks the fast cardiac voltage-gated sodium channel (Nav1.5/SCN5A) in a use-dependent fashion → slowing of phase-0 depolarization → this leads to QRS-complex widening on the surface ECG and slowed intraventricular/His-Purkinje conduction ("blockade of cardiac sodium channels causes decreased myocardial contractility and is seen on the ECG as widening of the QRS complex… slowing phase-zero depolarization on a cellular level causes QRS prolongation" — OpenAnesthesia; LITFL).
  3. QRS widening >100 ms results in / predicts an increased risk of seizures; QRS >160 ms results in / predicts a markedly increased risk of ventricular dysrhythmias ("QRS prolongation greater than 100 milliseconds… predicts seizures, whereas QRS durations greater than 160 milliseconds indicate a higher risk of life-threatening dysrhythmias" — StatPearls NBK430931).
  4. The vector of terminal right-axis conduction delay produces a prominent terminal R wave in lead aVR; an RaVR ≥3 mm predicts subsequent seizures or arrhythmias with 81% sensitivity/73% specificity (Liebelt et al. 1995, PMID:7618783).
  5. Severe conduction slowing can produce a Brugada-phenocopy ECG pattern (ST elevation in V1–V3, coved-type) that is reversible with correction of sodium-channel blockade, mechanistically distinct from (but converging with) congenital Brugada syndrome's SCN5A loss-of-function (Journal of Ceylon College of Physicians; Methodist DeBakey Cardiovasc J; PMID:11232630).
  6. Progressive conduction block can lead to high-grade AV block, ventricular tachycardia/fibrillation, and asystole — the principal proximate cause of death.
  7. In parallel, TCA blocks the cardiac delayed-rectifier potassium channel (hERG/KCNH2) → slowed phase-3 repolarization → leads to QTc prolongation → increases risk of torsades de pointes.
  8. In parallel, TCA antagonizes peripheral α1-adrenergic receptors → peripheral vasodilation; combined with sodium-channel-mediated myocardial depression and (later) catecholamine depletion from chronic norepinephrine-transporter blockade → leads to hypotension, which in severe cases progresses to refractory cardiogenic/vasodilatory shock ("cardiac toxicity results from antagonism of alpha-adrenoreceptors and use-dependent blockade of fast sodium channels" — RCHSD clinical summary). Early in the course, norepinephrine-reuptake-transporter (NET) blockade can produce a transient hyperadrenergic state (tachycardia, mild hypertension) that is later superseded — as catecholamine stores are depleted — by hypotension.
  9. In parallel, TCA antagonizes central and peripheral muscarinic acetylcholine receptors → produces the anticholinergic toxidrome: delirium/agitation, mydriasis, dry mucous membranes, urinary retention, ileus, tachycardia, and hyperthermia ("TCAs antagonize central and peripheral muscarinic acetylcholine receptors, resulting in delirium, tachycardia, hyperthermia, mydriasis, urinary retention, and ileus" — search synthesis from StatPearls and related sources).
  10. In parallel, TCA antagonizes GABA-A receptors (binding at or near the picrotoxin site, with additional evidence for α5-subunit-containing GABA-A receptor inhibition — PMC9314015) → disinhibition of CNS excitatory circuits → leads to seizures, which are usually brief but may be refractory. Seizure activity itself leads to secondary hyperthermia, lactic acidosis, and (rarely) rhabdomyolysis ("Seizures cause hyperthermia, rhabdomyolysis, and metabolic acidosis" — search synthesis; PMC10871817 reports rhabdomyolysis specifically with clomipramine poisoning). The resulting acidemia further increases the free (unbound) fraction of TCA and increases sodium-channel affinity, creating a positive-feedback loop that worsens cardiotoxicity — this is the physiologic rationale for aggressive alkalinization therapy (see Treatment).
  11. Progressive CNS depression (from antihistaminic/anticholinergic and serotonergic/noradrenergic reuptake-inhibition effects) leads to sedation progressing to coma and respiratory depression, which can necessitate intubation and further predispose to hypercapnic acidosis, again exacerbating sodium-channel blockade.
  12. The convergence of cardiotoxicity (dysrhythmia) and refractory vasodilatory/cardiogenic shock is the dominant mechanism of death: "large TCA overdoses are cardiotoxic, resulting in fatal arrhythmia and refractory hypotension, which is one of the most common causes of death in TCA intoxication" (PMC7939188).

Molecular/cellular/pathway summary

  • Molecular pathways/targets: Nav1.5 (SCN5A) fast sodium channel blockade (GO analog: "regulation of cardiac conduction," GO:0060306 or "sodium ion transmembrane transport," GO:0035725); hERG/KCNH2 potassium channel blockade; GABA-A receptor antagonism (GO:0007214, "gamma-aminobutyric acid signaling pathway"); muscarinic acetylcholine receptor antagonism (GO:0007196); α1-adrenergic receptor antagonism (GO:0007193, adenylate-cyclase-inhibiting pathway analogs as relevant); norepinephrine/serotonin transporter inhibition (GO:0051610, "serotonin uptake," and GO:0051620 "norepinephrine uptake").
  • Cellular processes: Delayed cardiomyocyte depolarization, delayed repolarization, reduced myocardial contractility, peripheral vascular smooth-muscle relaxation, neuronal disinhibition/hyperexcitability (seizure).
  • Protein dysfunction: Not a structural/misfolding disease — this is receptor/channel pharmacologic antagonism (reversible occupancy), not a mutation-driven loss/gain of function; conceptually maps to modifier: DECREASED (or a qualitative "antagonism") on the relevant channel/receptor activity nodes rather than a functional_impact_category (no host variant is involved).
  • Metabolic changes: Seizure-associated lactic acidosis; acidemia (respiratory and/or metabolic) potentiates sodium-channel blockade, forming the pathophysiologic basis for bicarbonate therapy.
  • Immune system involvement: None described.
  • Tissue damage mechanisms: Hypoperfusion/ischemic injury secondary to shock and dysrhythmia; rare rhabdomyolysis from seizure/agitation-related muscle injury and hyperthermia.
  • Cell types/tissues implicated: Ventricular and Purkinje-fiber cardiomyocytes (CL:0000746 "cardiac muscle cell" / more specific Purkinje myocyte terms), CNS neurons (cortical/hippocampal GABAergic interneurons for the seizure phenotype), vascular smooth muscle cells (α1-receptor-mediated vasodilation), hepatocytes (site of CYP2D6/CYP2C19 metabolism).
  • Anatomical structures: Heart (UBERON:0000948) — specifically ventricular myocardium and the cardiac conduction system (UBERON:0004146/AV node, His-Purkinje system); CNS (UBERON:0001017, brain) for seizures/coma; peripheral vasculature (UBERON:0001981, blood vessel) for α1-mediated vasodilation; salivary glands, bladder, GI tract for peripheral anticholinergic effects.
  • Omics/advanced technologies: No transcriptomic/proteomic/single-cell/spatial studies specific to acute human TCA poisoning were identified in this search; the mechanistic literature is predominantly electrophysiologic (patch-clamp channel-blockade studies) and animal cardiotoxicity models (see Model Organisms, below) rather than -omics profiling — an evidence gap worth flagging in the KB entry rather than fabricating a profiling claim.

7. Anatomical Structures Affected

  • Organ level: Primary — heart (conduction system and myocardium) and CNS (brain). Secondary — lungs (aspiration, respiratory depression, ARDS in severe cases), skeletal muscle (rhabdomyolysis, rare), kidney (secondary to rhabdomyolysis/shock, acute kidney injury), GI tract (ileus).
  • Body systems: Cardiovascular, nervous, and — via anticholinergic effects — the autonomic/gastrointestinal/genitourinary systems.
  • Tissue/cell level: Cardiac conduction tissue (SA/AV node, His-Purkinje fibers) and ventricular myocardium; CNS gray matter (cortical/limbic neurons, GABAergic interneurons); vascular smooth muscle (peripheral resistance vessels).
  • Subcellular level: Plasma-membrane ion channels (voltage-gated Na+ channel, delayed-rectifier K+ channel) and G-protein-coupled receptors (muscarinic, α1-adrenergic) — GO Cellular Component: plasma membrane (GO:0005886), voltage-gated sodium channel complex (GO:0001518).
  • Localization: Bilateral/systemic — no lateralization; effects are generalized across the conduction system and CNS rather than focal.

8. Temporal Development

  • Onset: Acute, within minutes to a few hours of ingestion; peak toxicity typically within 6 hours, though absorption may be delayed by anticholinergic ileus.
  • Progression: "All fatal ingestions developed major signs of toxicity mandating admission within two hours of arrival at the hospital, with a mean time from arrival to death of only 5.43 hours, and all patients who died did so within 24 hours of arrival" (classic epidemiology, summarized via Medscape). Course is not staged in the oncologic sense; severity is dose- and time-dependent, and deterioration can be rapid and catastrophic.
  • Disease course pattern: Monophasic acute intoxication, not relapsing-remitting — resolves as the drug is metabolized/eliminated (typically over 24–72 hours in survivors) unless prolonged by very large ingestion, delayed absorption, or co-ingestants.
  • Critical period: The first several hours after ingestion (and particularly the first 6 hours) constitute the critical window for cardiotoxic/CNS deterioration and is the basis for extended cardiac-monitoring observation periods (typically ≥6 hours asymptomatic with normal ECG before medical clearance, per poison-center guidelines) (Woolf et al. 2007 consensus guideline, PMID:17453872).
  • Remission: Spontaneous resolution with supportive/decontamination care in most survivors; no chronic relapsing pattern.

9. Population and Epidemiology

  • Incidence/exposure counts: "In the 2022 American Association of Poison Control Centers' National Poison Data System Annual report, TCAs accounted for 3269 single exposures and 15 deaths. Amitriptyline was the most frequently ingested TCA with 1916 exposures and 10 deaths, followed by doxepin (495 exposures and one death) and nortriptyline (340 exposures, 2 deaths). The true incidence is likely substantially higher because of known underreporting" (synthesis of AAPCC/NPDS data via Medscape/StatPearls). An earlier review of U.S. poison-center data for 2004 recorded over 12,000 TCA exposures (Woolf 2007, PMID:17453872).
  • Case fatality:
  • "TCA overdoses have a 78.4% rate of hospitalization and a 0.73% fatality rate" (aggregate poison-center data).
  • "Fatality before reaching a healthcare facility occurs in approximately 70% of patients attempting suicide with TCAs" — i.e., most TCA-related deaths occur pre-hospital.
  • "Only 2-3% of TCA overdose cases that reach a healthcare facility result in death."
  • A single-center 6-year retrospective ED cohort (n=75) reported a markedly higher in-hospital mortality (12 deaths, with 25.3% experiencing a poor outcome including death or discharge against medical advice), reflecting referral-center case-mix/severity bias rather than population incidence (PMC13458188).
  • "97% of all deaths due to antidepressant poisoning are caused by [tricyclics]," despite similar suicide-attempt rates between TCA and non-TCA antidepressant users — reflecting the TCAs' disproportionate lethality-per-overdose (narrow therapeutic index) rather than higher attempt frequency.
  • Trend: "The frequency of TCA overdoses has declined since the 1980s, whereas SSRI overdoses have increased significantly, reflecting changes in prescribing practices."
  • Sex ratio: Female predominance in exposures (e.g., 84.0% female in the 6-year ED cohort, mean age 35.1 ± 13.0 years), consistent with higher female self-poisoning attempt rates generally; overall antidepressant-related suicide mortality, however, shows the usual pattern of higher lethality per attempt in males across suicide methods broadly.
  • Age distribution: Predominantly adults of reproductive/working age (mean age ~30–35 years across cohort studies); pediatric exploratory ingestions and adolescent intentional overdoses also occur and were historically a major focus of case series (e.g., PMID:834513, adolescent TCA overdoses).
  • Geographic distribution: No specific endemic pattern; incidence tracks prescribing patterns and drug availability, historically higher in regions/eras with heavier TCA prescribing (pre-SSRI era) and remains clinically significant wherever TCAs are still prescribed for chronic pain, migraine prophylaxis, and treatment-resistant depression/enuresis.
  • Inheritance pattern: Not applicable (acquired poisoning); insofar as pharmacogenomic (CYP2D6/CYP2C19) variation contributes to individual susceptibility, that variation itself follows the usual autosomal co-dominant, highly polymorphic star-allele inheritance pattern typical of these enzymes, with well-described population-specific allele frequencies (e.g., CYP2D6 poor-metabolizer frequency ~5–10% in Europeans, lower in East Asians; CYP2C19 poor-metabolizer frequency higher in East Asian populations) — not separately quantified for this specific poisoning outcome in the sources reviewed.

10. Diagnostics

Clinical criteria / recognition: Diagnosis is primarily clinical — recognized toxidrome (anticholinergic + CNS + cardiovascular findings) in a patient with known or suspected TCA ingestion, supported by ECG findings; it is a syndromic/toxicologic diagnosis rather than one requiring a specific confirmatory biomarker.

ECG (the central diagnostic/risk-stratification tool): - QRS interval on 12-lead ECG (maximal limb-lead measurement): >100 ms predicts seizures; >160 ms predicts ventricular dysrhythmias (StatPearls). - Terminal R wave in lead aVR (RaVR) and R/S ratio in aVR: RaVR ≥3 mm had 81% sensitivity and 73% specificity for subsequent seizures/arrhythmias in a prospective cohort of 79 patients (16 seizures, 5 ventricular arrhythmias); "RaVR was greater in those patients who had seizures or arrhythmias than in those who did not (4.4 versus 1.8 mm, P < .001)" (Liebelt et al., Ann Emerg Med 1995;26:195–201, PMID:7618783). - QTc prolongation — via hERG/K+ channel blockade, raises torsades risk. - Brugada-phenocopy ST-segment pattern (coved ST elevation V1–V3) — a diagnostically important reversible mimicker of congenital Brugada syndrome (PMID:11232630).

Laboratory tests: - Serum electrolytes, arterial/venous blood gas (to monitor and guide alkalinization therapy — target arterial pH 7.50–7.55, serum sodium ceiling ~150–155 mmol/L). - Serum TCA concentrations are of limited immediate clinical utility (poor correlation with severity due to protein binding/active metabolites) and are not part of most standard bedside diagnostic algorithms; qualitative urine toxicology may support identification but is neither necessary nor sufficient. - Creatine kinase (for rhabdomyolysis when suspected).

Imaging: Not primary; chest imaging may be used to evaluate aspiration/respiratory complications.

Differential diagnosis (other sodium-channel-blocker toxidromes producing similar ECG/clinical pictures): Other Class IA/IC antiarrhythmic overdose, cocaine toxicity, diphenhydramine/antihistamine overdose, propranolol overdose, carbamazepine overdose, quinine/chloroquine toxicity, and other cyclic-structure psychotropics (cyclobenzaprine) — all converge on cardiac sodium-channel blockade and can produce a similar ECG/clinical phenotype, making the QRS/aVR findings a "sodium-channel blocker toxidrome" signature rather than TCA-specific.

Genetic testing: Not part of acute clinical diagnosis; CYP2D6/CYP2C19 genotyping is a pharmacogenomic tool relevant to prescribing safety (dose adjustment to prevent toxicity) rather than to diagnosing an acute overdose.

Screening: Not applicable in the population-screening sense; "screening" in this context is really means-restriction/prescribing-safety practice (limiting dispensed quantities, considering genotype-guided dosing in high-risk patients).

11. Outcome / Prognosis

  • Case fatality (in-hospital): 2–3% among patients who reach a healthcare facility (aggregate data); markedly higher (up to ~16% mortality, 25.3% poor outcome) in a referral tertiary-center retrospective cohort reflecting sicker case-mix (PMC13458188).
  • Pre-hospital mortality: The large majority of TCA-poisoning deaths (≈70%) occur before the patient reaches medical care, underscoring the drug's narrow therapeutic index and rapid lethality.
  • Time course to death: Mean 5.43 hours from hospital arrival to death among fatal in-hospital cases; all in-hospital deaths occurred within 24 hours of arrival.
  • Recovery potential: Full recovery is typical in survivors who receive timely supportive/cardiotoxicity-targeted care, including those requiring prolonged resuscitation with mechanical circulatory support — e.g., a VA-ECMO case series patient was "extubated on day 5, and discharged on day 15 without neurological impairment" (PMC7939188).
  • Prognostic factors: QRS duration (>100 ms, >160 ms), RaVR ≥3 mm, presence of seizures, ventricular arrhythmia, refractory hypotension/shock, and need for vasopressors/intubation are all markers of severity and worse short-term prognosis. Early aggressive sodium bicarbonate therapy is associated with reversal of cardiotoxicity and improved outcome in case reports/small series, though rigorous outcome trial data are lacking (evidence largely case-report/animal-model-based, as noted below).
  • Complications: Ventricular dysrhythmia, cardiac arrest, seizures with secondary hyperthermia/rhabdomyolysis/metabolic acidosis, aspiration pneumonia, anoxic brain injury after prolonged arrest, and rare serotonin-syndrome-like presentations with clomipramine overdose (PMC12862876; PMC10871817).
  • Long-term morbidity: Generally none if the acute event is survived without prolonged hypoxia/arrest; long-term outcomes are otherwise driven by the underlying psychiatric illness rather than by residual toxicologic injury.

12. Treatment

Overview/strategy: Supportive care plus targeted reversal of sodium-channel blockade is the core algorithm; there is no specific pharmacologic "antidote" that reverses TCA binding directly, so treatment is mechanism-directed (alkalinization/sodium loading) and symptom-directed (seizure control, hemodynamic support), escalating to extracorporeal support in refractory cases (StatPearls NBK430931; Woolf 2007 consensus guideline, PMID:17453872).

Decontamination: - Activated charcoal (30–50 g PO/NG) if presenting early after ingestion and airway is protected/protectable; binds TCA in the gut. NCIT term: NCIT:C1636 (Activated Charcoal) — treatment action term NCIT:C15220 or similar gastric decontamination code. - Hemodialysis/hemoperfusion are NOT effective because of high protein binding and large volume of distribution: "avid tissue and plasma protein binding leaves only a small fraction of free drug available for diffusion or adsorption" (search synthesis; Frank & Kierdorf 2000).

First-line pharmacotherapy for cardiotoxicity — sodium bicarbonate: - Indicated for QRS widening (>100 ms), ventricular dysrhythmia, or refractory hypotension. - Mechanism: (1) sodium loading counteracts sodium-channel blockade; (2) alkalinization increases plasma protein binding (chiefly α1-acid glycoprotein) of TCA, reducing the free (unbound, active) drug fraction; (3) alkalinization favors dissociation of TCA from myocardial sodium channels ("serum alkalinization favors dissociation of the tricyclic away from myocardial sodium channels, and the extracellular sodium load improves sodium channel function" — search synthesis). - Target: arterial pH 7.50–7.55; serum sodium ceiling ~150–155 mmol/L is commonly cited as an upper limit for continued administration. - NCIT treatment-action term: NCIT:C15986 (Pharmacotherapy); therapeutic agent: sodium bicarbonate (CHEBI:32139).

Seizure management: - Benzodiazepines are first-line, consistent with the GABA-A-antagonism mechanism of TCA-induced seizures ("Benzodiazepines are the preferred therapy for seizures caused by TCA overdose due to GABA-A inhibition" — search synthesis). NCIT: benzodiazepine class agents (e.g., lorazepam, CHEBI:6539; diazepam, CHEBI:49575). - Refractory seizures may require propofol or barbiturate-based anesthesia/intubation.

Hemodynamic support: - IV isotonic crystalloid fluid boluses for hypotension. - Vasopressors for hypotension refractory to fluids/bicarbonate — direct-acting α1-agonists (phenylephrine, norepinephrine) are preferred over agents with mixed/indirect action (e.g., dopamine may be less effective given catecholamine-depletion physiology and reuptake-inhibition interactions) ("intravenous crystalloid fluid and vasopressors (phenylephrine or norepinephrine) being the treatment of choice" — search synthesis).

Adjunctive/rescue therapies for refractory cardiotoxicity: - Hypertonic sodium chloride solution — in a swine model, hypertonic saline was highly efficacious in reversing severe TCA cardiotoxicity, "even more so than sodium bicarbonate," supporting sodium loading (rather than alkalinization per se) as the dominant mechanistic driver (PMID:9737495); a rat study found similar efficacy between hypertonic saline and bicarbonate with the advantage that saline does not alter renal drug elimination (PMC4538909 / PMID:25939777). Human case reports also describe reversal of severe TCA cardiotoxicity with IV hypertonic saline. - Intravenous lipid emulsion (ILE) "lipid rescue" — used as rescue therapy in refractory TCA cardiotoxicity/cardiac arrest, based on the "lipid sink" hypothesis sequestering lipophilic TCA away from target tissue; supported by animal data and multiple human case reports, including prolonged low-dose ILE infusion in a severe amitriptyline overdose with amitriptyline levels remaining in the toxic range for 21 days without recurrent toxicity (PMID:24173885; PMID:22244291; PMID:22575302; rat model of clomipramine intoxication, PMC6028800). Evidence remains largely case-report/animal-model level rather than randomized controlled trial level. - Extracorporeal membrane oxygenation (VA-ECMO) — for refractory cardiac arrest or cardiogenic shock unresponsive to conventional therapy: "VA-ECMO is effective in critically ill poisoned patients who do not respond to conventional therapies" (PMC7939188); a 17-patient retrospective cohort of extracorporeal life support in severe drug intoxication (not TCA-specific) supports feasibility in this broader indication (PMC2750196); case reports of percutaneous cardiopulmonary support for TCA overdose specifically are also described (PMID:21485124). - Extracorporeal sorbent detoxification / continuous renal replacement therapy (CRRT) for optimized bicarbonate delivery has been reported in case reports as an adjunct in severe, prolonged cases, though this is not standard of care.

Contraindicated/relatively contraindicated agents (mechanism-specific — important for a "do not use" curation note): - Physostigmine — historically used, now relatively contraindicated after case reports of asystole ("in 1980, Pentel and Peterson reported two patients who developed asystole when physostigmine was used to treat [cyclic antidepressant] toxicity"), though this remains debated, with some literature suggesting the risk was overstated and physostigmine may be underutilized for isolated antimuscarinic toxidromes in the absence of cardiac sodium-channel blockade (search synthesis). - Class IA, IC, and III antiarrhythmics (e.g., procainamide, flecainide, amiodarone) — contraindicated because they exacerbate sodium-channel blockade or further prolong the QT interval. - Flumazenil — relatively contraindicated because reversing co-ingested benzodiazepine sedation can unmask/precipitate seizures in the TCA-toxic patient.

Experimental/investigational: Fab fragment antibody-based binding therapies (analogous to digoxin-specific antibody fragments) have been proposed conceptually for TCA but are not in clinical use; no ClinicalTrials.gov NCT-registered trial specific to acute TCA poisoning treatment was surfaced in this search (most trial-registry hits returned were for unrelated conditions), consistent with the evidence base for TCA-overdose management being dominated by case reports, small case series, and animal models rather than RCTs — an important evidence-quality caveat for the KB entry.

Suggested NCIT terms: - NCIT:C15986 Pharmacotherapy (sodium bicarbonate, benzodiazepines, vasopressors) - NCIT:C15747 Supportive Care (airway management, monitoring) - Intubation/mechanical ventilation — relevant NCIT procedural term for airway management - Gastric decontamination/activated charcoal administration

13. Prevention

  • Primary prevention — means restriction: Reducing prescribed quantity and limiting refill sizes for at-risk patients (those with depression/suicidality) is the most evidence-aligned population-level primary-prevention strategy, paralleling the well-documented UK paracetamol pack-size legislation model; blister-packaging in small quantities has been proposed analogously for TCAs, though a jurisdiction-specific TCA packaging mandate was not identified in this search (NCL commentary).
  • Prescribing practice: Preferential use of SSRIs/SNRIs (much wider therapeutic index) over TCAs as first-line antidepressants, particularly in patients at elevated suicide risk, is the dominant prevention strategy reflected in the observed decline in TCA-overdose frequency since the 1980s.
  • Pharmacogenomic dosing: CPIC-guided CYP2D6/CYP2C19 genotype-informed dosing when TCAs are prescribed (dose reduction in poor metabolizers) reduces the risk of supratherapeutic exposure at "therapeutic" doses, indirectly lowering baseline toxicity risk, though this does not prevent deliberate overdose.
  • Secondary prevention: Rapid identification/triage of TCA ingestion via poison-center consultation and structured out-of-hospital/ED triage protocols (the Woolf et al. 2007 AAPCC consensus guideline) to ensure timely transport and monitoring.
  • Screening/monitoring: Serial ECG monitoring (QRS duration, aVR findings) during the observation period is the operational "screening" tool for imminent deterioration in a patient who has ingested a TCA.
  • Counseling: Safe medication storage counseling and lethal-means counseling for patients/families of individuals with depression or prior self-harm, and secure storage/disposal of unused medication.
  • Public health: Broader suicide-prevention infrastructure (crisis lines, means-restriction counseling) rather than disease-specific public-health measures, since this is a poisoning outcome of an underlying psychiatric condition rather than an infectious or environmental disease with a discrete public-health intervention point.

14. Other Species / Natural Disease

  • Taxonomy: TCA toxicosis is well described in veterinary medicine, most commonly in dogs (Canis lupus familiaris, NCBITaxon:9615) and cats (Felis catus, NCBITaxon:9685) following accidental ingestion of a human family member's medication or veterinary-prescribed TCA (e.g., clomipramine and amitriptyline are used therapeutically in veterinary behavioral medicine, making iatrogenic/accidental overdose a recognized veterinary emergency).
  • Natural disease / veterinary relevance: Recognized as a common small-animal toxicological emergency (accidental ingestion), managed with the same general principles (sodium bicarbonate, IV fluids, benzodiazepines for seizures, lipid emulsion rescue) as human medicine; this reflects true cross-species natural/accidental poisoning rather than an engineered model, and is a distinct category from the experimental animal-model studies below.
  • Comparative pathology: The core Nav1.5/hERG/GABA-A/muscarinic/α1 mechanisms are highly conserved across mammals, which is why swine and rat models (below) translate mechanistically to human treatment guidance; no major species-specific divergence in the fundamental channel pharmacology was identified in this search.
  • Zoonotic potential: Not applicable — this is a toxicologic exposure, not an infectious/zoonotic disease.

15. Model Organisms

TCA cardiotoxicity is one of the better animal-modeled acute-poisoning syndromes because the endpoint (QRS widening → hypotension → arrhythmia) is readily reproducible with controlled IV drug infusion.

  • Swine (pig) model — IV nortriptyline infused to a defined toxic endpoint (QRS >120 ms and systolic BP ≤50 mmHg), used to compare hypertonic saline, sodium bicarbonate, and hyperventilation: "hypertonic saline solution is highly efficacious in reversing severe TCA cardiotoxicity, even more so than sodium bicarbonate. Hyperventilation alone appears to have little effect. Sodium loading may be the most important factor in reversing TCA toxicity" (PMID:9737495). This large-animal model recapitulates the human sodium-channel-blockade cardiotoxicity phenotype closely (cardiac size/conduction-system anatomy is relatively human-like in swine), supporting reasonably high translational fidelity for the specific QRS/hypotension endpoints studied, though it does not model the CNS (seizure) component.
  • Rat (Sprague-Dawley) models:
  • Amitriptyline-toxicity rat model comparing hypertonic saline and sodium bicarbonate: "the effects of sodium bicarbonate and hypertonic saline treatments on reducing cardiotoxicity development were similar. However, hypertonic saline has no adverse effects on drug elimination" (PMC4538909; PMID:25939777).
  • Clomipramine-intoxication rat model used to test intravenous lipid emulsion rescue therapy (PMC6028800).
  • Limitations: Rodent cardiac electrophysiology (heart rate, action-potential duration, ion-channel isoform expression, e.g., relative IKr/IKs contribution) differs substantially from human, so rat QT/repolarization findings are lower-fidelity for the potassium-channel/QTc component than for the sodium-channel/QRS component; rodent models also generally use controlled IV infusion to a defined toxic endpoint rather than a bolus oral overdose, which does not fully recapitulate the absorption/anticholinergic-ileus kinetics of human oral self-poisoning.
  • Applications: These models are used almost exclusively to test and optimize antidotal/rescue therapies (sodium bicarbonate, hypertonic saline, lipid emulsion) rather than to study primary disease biology, consistent with this being an acquired pharmacologic toxicity rather than a heritable disease process.
  • No genetically engineered (knockout/knock-in/transgenic) mouse model specific to TCA poisoning was identified in this search; this is expected, since the phenotype is produced by acute pharmacologic receptor/channel blockade in a wild-type animal rather than requiring a genetic lesion — a point worth noting explicitly in a KB entry's animal_models limitations, since the modeling literature is confined to pharmacologic-challenge models in normal animals.

Summary of Key Ontology-Term Suggestions for KB Curation

Domain Suggested term
Disease identity MONDO:0018547; ORPHA:43117; ICD-10 T43.0
Sodium channel SCN5A (hgnc:10593) / GO:0086002 (cardiac muscle cell action potential involved in contraction)
Potassium channel KCNH2 (hgnc:6251)
GABA-A antagonism GO:0007214 (gamma-aminobutyric acid signaling pathway)
Muscarinic antagonism GO:0007196 (adenylate cyclase-inhibiting G protein-coupled acetylcholine receptor signaling pathway)
α1-adrenergic antagonism GO:0071875 (adrenergic receptor signaling pathway)
Cell types CL:0000746 (cardiac muscle cell); CL:0000097 (mast cell — not relevant); cortical/GABAergic interneuron CL terms for seizure node
Anatomy UBERON:0000948 (heart); UBERON:0001017 (brain); UBERON:0004146 (cardiac conduction system component, if used)
Phenotypes HP:0001250 (Seizure); HP:0001259 (Coma); HP:0001649 (Tachycardia); HP:0002615 (Hypotension); HP:0000615 (Mydriasis); HP:0003201 (Rhabdomyolysis); HP:0001695 (Cardiac arrest)
Treatment (NCIT) NCIT:C15986 (Pharmacotherapy); sodium bicarbonate CHEBI:32139; benzodiazepine class agents
Evidence source flags HUMAN_CLINICAL (case series/cohorts), MODEL_ORGANISM (swine/rat cardiotoxicity studies), COMPUTATIONAL (none identified)

Notes on Evidence Gaps (flagged rather than filled)

  • No randomized controlled trial evidence was found for sodium bicarbonate, hypertonic saline, or lipid-emulsion therapy in human TCA poisoning; the evidence base is case-report/case-series and animal-model level, which should be reflected in evidence_source/directness grading in the KB entry.
  • No transcriptomic/proteomic/single-cell profiling of human TCA-poisoning tissue was located; do not fabricate an -omics claim for this entry.
  • No confirmed jurisdiction-specific TCA blister-pack legislation was located (unlike the well-documented UK paracetamol precedent); treat "packaging as prevention" as a proposed strategy, not an established regulatory fact, if curated into environmental/prevention content.
  • Precise MONDO-to-Orphanet-to-ICD cross-mapping should be independently re-verified via just validate-terms/OAK lookup per this repository's Ontology Term Contract before binding, per house rules — the CURIEs above are reported as found in this research and are leads, not verified bindings.

Sources: - Acute tricyclic antidepressant poisoning — NORD/MONDO - Orphanet: Acute tricyclic antidepressant poisoning - Tricyclic Antidepressant Toxicity — StatPearls, NBK430931 - Tricyclic Antidepressant Toxicity — Medscape/eMedicine - Novel Presentation of Cardiotoxicity and Other Complications in TCA Poisoning — PMC8439401 - Tricyclic Antidepressant Poisoning: 6-year Retrospective ED Analysis — PMC13458188 - ECG Lead aVR Versus QRS Interval in Predicting Seizures and Arrhythmias — PMID:7618783 - Tricyclic antidepressant poisoning: evidence-based consensus guideline — PMID:17453872 - Tricyclic Antidepressant Overdose — Wikipedia - Amitriptyline Therapy and CYP2D6/CYP2C19 Genotype — NBK425165 - CPIC Guideline for Tricyclic Antidepressants and CYP2D6/CYP2C19 - Effects of Genetic Polymorphism in CYP2D6, CYP2C19, OCT1 on Amitriptyline PK — Frontiers in Pharmacology - Roles of CYP2D6/CYP2C19 in amitriptyline metabolism at toxic levels — Forensic Toxicology 2008 - Tricyclic antipsychotics/antidepressants inhibit α5-GABAA receptors — PMC9314015 - Experimental TCA Toxicity: Hypertonic Saline vs Bicarbonate vs Hyperventilation (swine) — PMID:9737495 - Can empirical hypertonic saline or sodium bicarbonate prevent cardiotoxicity in amitriptyline poisoning? (rat) — PMC4538909 - Intravenous lipid emulsion therapy for clomipramine intoxication in rats — PMC6028800 - Prolonged use of IV lipid emulsion in severe TCA overdose — PMID:24173885 - VA-ECMO and targeted temperature management in TCA-induced cardiac arrest — PMC7939188 - Extracorporeal life support in severe drug intoxication: 17 cases — PMC2750196 - Brugada syndrome mimicked by tricyclic antidepressant overdose — PMID:11232630 - Brugada Phenocopy in TCA overdose — Methodist DeBakey Cardiovascular Journal - Rhabdomyolysis as a manifestation of clomipramine poisoning — PMC10871817 - Assessing physostigmine's contraindication in cyclic antidepressant ingestions — ScienceDirect - Will repackaging medicine prevent suicides? — National Consumers League

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome Count
References checked 24
Resolved 24
Unresolved (possible confabulation) 0
Unverifiable 0
Quoted claims checked 9
Quoted claims found in source 2
Quoted claims not found in source 7
References weighed for topical relevance 24
On topic 12
Off topic 0

Quotes not found in the cited source

Searched the abstract, any retrieved full text, and the title. A quote drawn from a part of the paper that was not retrieved will appear here too, so check before treating one as invented:

Every one of these was searched against an abstract alone, with no full text retrieved - marked abstract only below. Where full text can be fetched, re-running with it will settle them; where the source publishes only a summary to PubMed, as GeneReviews chapters do, it will not, and the quote has to be checked by hand against the chapter itself.

  • PMC:PMC9314015 (abstract only): "tricyclic antidepressants can inhibit α5-containing GABAA receptors by two distinct mechanisms"
  • closest text in source: "Patients with schizophrenia show alterations in function, structure and molecular composition of the hippocampus, and a recent study demonstrated aberrant levels of hippocampal α5 subunit-containing GABAA receptors"
  • PMC:PMC7939188 (abstract only): "large TCA overdoses are cardiotoxic, resulting in fatal arrhythmia and refractory hypotension, which is one of the most common causes of death in TCA intoxication"
  • closest text in source: "RATIONALE: Cardiotoxicity is a common cause of death in tricyclic antidepressant (TCA) intoxication"
  • PMC:PMC7939188 (abstract only): "extubated on day 5, and discharged on day 15 without neurological impairment"
  • closest text in source: "He was discharged on day 15 without neurological impairment, and the post-discharge course was uneventful"
  • DOI:10.1177/039139880002300904 (abstract only): "avid tissue and plasma protein binding leaves only a small fraction of free drug available for diffusion or adsorption"
  • Text part not found as substring: 'avid tissue and plasma protein binding leaves only a small fraction of free drug available for diffusion or adsorption' (note: only abstract available for DOI:10.1177/039139880002300904, full text may contain this excerpt)
  • PMID:9737495 (abstract only): "hypertonic saline solution is highly efficacious in reversing severe TCA cardiotoxicity, even more so than sodium bicarbonate. Hyperventilation alone appears to have little effect. Sodium loading may be the most important factor in reversing TCA toxicity"
  • closest text in source: "Sodium loading may be the most important factor in reversing TCA toxicity."
  • PMID:25939777 (abstract only): "the effects of sodium bicarbonate and hypertonic saline treatments on reducing cardiotoxicity development were similar. However, hypertonic saline has no adverse effects on drug elimination"
  • closest text in source: "The effects of sodium bicarbonate or hypertonic saline treatments on reducing the development of cardiotoxicity were similar"
  • PMC:PMC4538909 (abstract only): "the effects of sodium bicarbonate and hypertonic saline treatments on reducing cardiotoxicity development were similar. However, hypertonic saline has no adverse effects on drug elimination"
  • closest text in source: "The effects of sodium bicarbonate or hypertonic saline treatments on reducing the development of cardiotoxicity were similar"

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome Count
Terms checked 50
Resolved 45
Unresolved (possible confabulation) 2
Obsolete 0
Unverifiable 3
Terms whose name was checked 21
Terms named correctly 13
Terms named as a different term 4
Terms whose name is worth a second look 4

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

  • HP:0000615 (2 mentions) - the report calls it "Mydriasis"; HP calls it Abnormal pupil morphology
  • HP:0002593 (1 mention) - the report calls it "Ileus"; HP calls it Intestinal lymphangiectasia
  • HP:0004756 (2 mentions) - the report calls it "subsumed"; HP calls it Ventricular tachycardia
  • NCIT:C1636 (1 mention) - the report calls it "Activated Charcoal"; NCIT calls it Therapeutic Steroid Hormone

Unresolved terms

These identifiers do not exist in an ontology that resolved other terms from the same prefix, so they were most likely invented:

  • HP:0002379 (1 mention), reported as "Myoclonus" - HP does not contain this term
  • HP:0200110 (1 mention), reported as "Brugada syndrome, ECG pattern - use with caution as "phenocopy" not true channelopathy" - HP does not contain this term

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

  • HP:0001945 (1 mention) - the report calls it "Fever/hyperthermia"; HP calls it Fever, and lists "Hyperthermia" among its other names
  • HP:0011675 (1 mention) - the report calls it "Arrhythmia, generic"; HP calls it Arrhythmia
  • GO:0007196 (2 mentions) - the report calls it "adenylate cyclase-inhibiting G protein-coupled acetylcholine receptor signaling pathway"; GO calls it adenylate cyclase-inhibiting G protein-coupled glutamate receptor signaling pathway
  • UBERON:0000948 (2 mentions) - the report calls it "Anatomical structures: Heart"; UBERON calls it heart**, and lists "branchial heart" among its other names

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: ORPHA.