A 30-year-old man presents after an amitriptyline overdose. His ECG shows a QRS duration of 120 ms and a terminal R wave in aVR. The most appropriate pharmacological therapy to correct the cardiac conduction abnormalities and prevent arrhythmias is:
- A Lorazepam
- B Sodium bicarbonate ✓
- C Magnesium sulfate
- D Atropine
Correct answer: B. Sodium bicarbonate
Explanation
Sodium bicarbonate is the drug of choice for cardiac toxicity in tricyclic antidepressant overdose. It works by alkalinizing the serum, which reduces the free fraction of the drug and decreases sodium channel blockade, thereby narrowing the QRS complex. Lorazepam treats seizures. Magnesium sulfate is used for torsades de pointes. Atropine is used for bradycardia.
Reference: Katzung and Trevor's Pharmacology, 12th ed.
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