Loperamide and cardiac events: Is high-dose use still safe for chemotherapy-induced diarrhea?

High-dose loperamide is often used for the acute management of chemotherapy-induced diarrhea, with a maximum daily dosing of up to 24 mg. Recently, the US Food and Drug Administration has issued a warning that loperamide can cause rare serious cardiac events, including QT prolongation, torsades de pointes, cardiac arrest and death. Most events were reported in patients taking very high doses for an extended period of time. Daily intake ranged from 64 mg to 1600 mg, often continuously for weeks or months. In addition, the reported serum levels of loperamide ranged from 22 ng/mL to 210 ng/mL, which is likely significantly higher than that expected from patients taking the recommended doses for chemotherapy-induced diarrhea. Overall, the incidence of serious cardiac events associated with loperamide remains low. In balance, the risk of uncontrolled complications from chemotherapy-induced diarrhea is likely greater than the rare cardiac risk associated with the chronic misuse of much higher doses of loperamide.