Cimetidine increases serum mebendazole concentrations. Implications for treatment of hepatic hydatid cysts.

Combined administration of cimetidine and mebendazole resulted in the complete resolution of previously unresponsive hydatid cysts in patients with peptic ulcer disease.

Abstract

In eight patients (five with peptic ulcer disease and three with hydatid cysts), the [14C]-aminopyrine breath test (ABT) and maximum serum concentration of mebendazole following a dose of 1.5 g of mebendazole three times daily were determined before and after treatment with cimetidine (400 mg three times daily for 30 days). Serum mebendazole concentrations were measured in blood samples taken 2 h after each drug intake. Cimetidine lowered the 14CO2 specific activity (SA) at 1 h (P less than 0.01) and increased the maximum serum concentration of mebendazole (P less than 0.01). A significant correlation was found between SA at 1 h and the highest concentration of mebendazole before (r = -0.71, P less than 0.05) and after (r = -0.82, P less than 0.05) cimetidine ingestion. Combined administration of cimetidine and mebendazole resulted in the complete resolution of previously unresponsive hydatid cysts.