A young man presents 12 hours after taking an overdose of a tricyclic antidepressant with prolonged QRS, hypotension and seizures. The most appropriate intervention to counteract cardiac toxicity is administration of:

• A Flumazenil IV
• B Sodium bicarbonate IV bolus ✓
• C Physostigmine IV
• D Calcium gluconate IV

Explanation

TCA overdose causes cardiac sodium channel blockade (quinidine-like) resulting in QRS widening and ventricular arrhythmias. Intravenous sodium bicarbonate alkalinises the blood (increasing pH to 7.45–7.55) and provides a sodium load — both of which reduce TCA binding to cardiac Na+ channels, narrowing QRS and preventing malignant arrhythmias. Flumazenil reverses benzodiazepine toxicity. Physostigmine was historically used but can precipitate seizures in TCA overdose and is contraindicated. Calcium gluconate treats hyperkalemia/calcium channel blocker toxicity.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.