Tricyclic antidepressant overdose

Tricyclic antidepressants are all toxic in overdose but the most toxic are dothiepin and amitriptyline.

Features of tricyclic overdose:
  • Anticholinergic 
    • blurred vision 
    • dilated pupils 
    • dry mouth 
    • tachycardia 
    • urinary retention 
    • pyrexia 
    • constipation
  • Alpha adrenergic blockade
    • hypotension 
  • Sodium channel blockade 
    • prolongation of QRS, PR and QT leading to risk of arrhythmias 

  • UEs – look for hypokalaemia 
  • ABG –look for acidosis, classically mixed metabolic and respiratory
  • ECG - ?long PR/long QT/broad QRS 

  • ECG monitoring and observation
  • Activated charcoal if patient presents within 1 hour and has an intact airway 
  • Gastric lavage if potentially life-threatening OD and within 1 hour of ingestion 
  • IV fluids if hypotensive 
  • Sodium bicarbonate if acidotic or arrthymias or hypotensive
  • Avoid class Ia/Ic/III antiarrythmics as they prolong QT 
  • Use benzodiazepines to control seizures; avoid phenytoin 
  • Potentially ITU

Small print gem: Even if mixed OD with benzodiazepines avoid flumazenil as this increases risk of seizures and arrhythmias 

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Secret collector of interesting anonymised ECGs. Fan of the Bath Photomarathon. Lover of cream teas. [Sarah Hudson] (Your Picture)