GuidelinesOther guideline
Tricyclic Antidepressant Poisoning
Tricyclic antidepressant poisoning
Mechanism of toxicity
Toxic dose
Symptoms and signs of poisoning
Special investigations
Management
Mechanism of toxicity
Cardiovascular toxicity (main cause of death): noradrenalin re-uptake inhibition, anti-cholinergic and alpha-blocking effects.
Toxic dose
15 to 20 mg/kg
Symptoms and signs of poisoning
- Cardiovascular: sinus tachycardia, hypotension, conduction abnormalities and arrhythmias (PR and QRS prolongation, ST and T wave changes, heart block, atypical and regular ventricular tachycardia, and ventricular fibrillation)
- Anticholinergic: flushing, dry mouth, dilated pupils, hyperpyrexia, urinary retention, constipation
- Neurological: drowsiness, agitation, hallucinations, hyperreflexia, myoclonus, choreoathetosis, muscle twitching/ rigidity, convulsions, coma
- Respiratory: respiratory depression, aspiration pneumonia, ARDS, pulmonary oedema
Special investigations
- Arterial blood gas
- TCA concentrations: serious cardio-toxicity: >500 ng/mL (>1000 ng/mL can be fatal)
Management
| Intervention | Not effective | Consider | Indicated |
| Gastric lavage | |||
| Early post-ingestion activated charcoal | |||
| Multiple dose active charcoal | |||
| Dialysis | |||
| Charcoal haemoperfusion |
Symptomatic and supportive:
- Wide QRS complex (> 100 msec): sodium bicarbonate 0.5–2 mEq/kg IV bolus followed by IV infusion (decreases cardiotoxicity). Aim for a pH of 7.45–7.55.
- Monitor: sodium and potassium levels closely
- Seizures: diazepam followed by phenobarbital/propofol if refractory. Avoid phenytoin as it may worsen cardiac arrthytmias.
Monitoring:
- Cardiac monitoring: prolonged monitoring needed in severe poisoning as half-lives of the TCAs vary from 24–72 hours and are increased in overdose