Loperamide metabolite-induced cardiomyopathy and QTc prolongation

Loperamide is an over-the-counter, peripherally acting, μ-opioid receptor agonist used for the treatment of diarrhea. In recent times users have found that at higher doses, loperamide crosses the blood-brain barrier and reaches central μ-receptors in the brain, leading to central opiate effects including euphoria and respiratory depression. We report a case of a 37-year-old female who attempted suicide with over 200 loperamide tablets. During her overdose, her QTc was significantly prolonged at >600 ms. Our case aims to add to the growing body of literature describing life-threatening ventricular arrhythmias associated with loperamide toxicity and further suggests that a metabolite of loperamide, desmethylloperamide, may play a role in the pathogenesis.