Ventricular Tachycardia Triggered by Loperamide and Famotidine Abuse

Abstract

A 32-year-old male developed recurrent ventricular tachycardia after taking mega doses of loperamide and famotidine in order to experience an opiate-like euphoric effect. He was taking up to 200 mg of loperamide and multiple doses of famotidine each day. He developed palpitations and syncope. Electrocardiography demonstrated ventricular tachycardia and QT interval prolongation (corrected QT interval was 597 ms). He was diagnosed with loperamide-induced QT prolongation resulting in incessant ventricular tachycardia. Loperamide was discontinued, and he was treated with electrolyte replacement, supportive care, and monitoring. After 5 days, his electrocardiogram (ECG) normalized and he had no more ventricular tachycardia. A Naranjo assessment score of 8 was obtained, indicating a probable relationship between QT prolongation and his use of loperamide. Large doses of loperamide can cause QT interval prolongation and life-threatening arrhythmias. These effects may be accentuated when histamine-2 receptor blockers are also abused.

Fig. 1

Electrocardiogram (ECG) demonstrating sinus tachycardia (rate 101 beats/min), first-degree AV block (PR interval 255 ms), nonspecific intraventricular conduction delay (QRS duration 158 ms), and QT interval prolongation (corrected QT interval 597 ms)

Fig. 2

Electrocardiogram (ECG) demonstrating a monomorphic ventricular tachycardia rate of 150 beats/min

Fig. 3

Electrocardiogram (ECG) demonstrating sinus rhythm (rate 72 beats/min), normal PR interval (188 ms), normal QRS duration (90 ms), and normal QT interval (corrected QT interval 389 ms)