A correlation between serum mebendazole concentrations and the aminopyrine breath test. Implications in the treatment of hydatid disease.

In 25 patients an [14C]-aminopyrine breath test (ABT) was performed immediately before the oral administration of 1.5-2 g of mebendazole three times daily. The concentration of mebendazole in serum was measured 2 h after each drug intake. A significant correlation was found between the results of ABT and the serum drug concentrations obtained after the second and third intake, as well as the highest concentration value. The ABT was repeated in six patients during a continuous treatment with mebendazole. In all of them this test indicated an increase in 14CO2 production with continued treatment. The results support the view that mebendazole is metabolized by the liver monooxygenase activity and behaves as an enzyme inducer.