Ventricular tachycardia associated with high-dose chronic loperamide use.

Loperamide is an antidiarrheal medication deemed by the U.S. Food and Drug Administration as safe enough to be sold as an over-the-counter medicine. Unlike other μ-opioid receptor agonists, loperamide acts specifically in the myenteric plexus in the gastrointestinal tract, making the potential for abuse low and reports of toxicity extremely rare. We present a case of a patient previously in good health who developed episodes of cardiac pauses, nonsustained ventricular tachycardia, and eventually runs of sustained ventricular tachycardia with hemodynamic instability. She required cardiopulmonary resuscitation, multiple cardioversions, and placement of a pacemaker. Her medical history was remarkable only for type 2 diabetes and chronic postcholecystectomy diarrhea. Metformin was the only prescription medication she was taking at the time of presentation. However, she reported that she had been taking an entire bottle of Equate brand loperamide (144 mg) daily for ~2 years. Loperamide overdoses associated with ventricular arrhythmias have been reported, but this is the first case to describe a serious ventricular arrhythmia associated with long-term use of a high dose of loperamide. Chronic overtreatment with loperamide may induce life-threatening arrhythmias.