A 45-year-old woman is brought unconscious after ingesting an unknown quantity of her amitriptyline tablets. ECG shows a QRS duration of 160 ms and sinus tachycardia with hypotension. The most appropriate immediate treatment is:
- A Intravenous amiodarone
- B Intravenous calcium gluconate
- C Intravenous sodium bicarbonate ✓
- D Intravenous flumazenil
Correct answer: C. Intravenous sodium bicarbonate
Explanation
Tricyclic antidepressant cardiotoxicity results from fast sodium channel blockade, producing QRS widening, ventricular dysrhythmias and hypotension. Alkalinisation with hypertonic sodium bicarbonate is the specific antidote: it reduces the free drug fraction available to the channel and reverses the conduction abnormality. Class IA and IC antiarrhythmics share the same sodium channel blockade and are contraindicated. Flumazenil is irrelevant and risks seizures.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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