A Heart-Wrenching Case of Loperamide Toxicity

Loperamide is an insoluble meperidine analog that is commonly used for diarrhea. It is an inexpensive and frequently available over the counter drug. While physicians are aware of its opioid effects, Loperamide use is also linked to cardiac conduction disturbances.

We present a case of Loperamide toxicity with QRS, Corrected QT interval (QTc) prolongation and ventricular arrhythmias such as ventricular tachycardia leading to cardiopulmonary resuscitation (CPR). The patient survived and was evaluated to have prolonged QT interval. He later disclosed over the counter (OTC) and continued a regular use of Loperamide as an anti-diarrheal agent. During the rest of hospital stay, serial Electrocardiograms (ECGs) showed improvement in QT interval and patient was successfully discharged. 

Loperamide inhibits intestinal peristalsis through its peripheral µ-opioid receptor agonism, as well as calcium channel blockade. Loperamide abuse is increasing, as patients use it either to experience euphoric effects or to attenuate the effects of opioid withdrawal.At high doses, Loperamide blocks cardiac sodium and potassium channels, resulting in prolonged QRS and QT intervals which can proceed to cardiac rhythm disturbances. Our case shows the acute and delayed cardiac effects of Loperamide toxicity which the treating physician should be made well aware of.