Preliminary observations on the biliary elimination of mebendazole and its metabolites in patients with echinococcosis.

The biliary excretion of mebendazole has been investigated in two patients to whom it was given for the treatment of echinococcosis, although it was found to be only partly effective. Oral mebendazole was extensively metabolized and the conjugated parent substance and its metabolites were excreted in the bile. One patient without cholestasis and with normal liver function had an apparent total biliary clearance (776 ml/min) which approached the hepatic plasma flow. The other patient with cholestasis and impairment of the hepatic drug metabolizing capacity showed a drastically reduced apparent total biliary clearance of 3.8 ml/min. The average plasma level of mebendazole was significantly lower in the former and higher in the latter patient (0.06 and 0.91 nmol/ml, respectively). The data suggest that impaired metabolism and/or biliary elimination can account for the higher plasma mebendazole level in patients with liver damage.