Effect of gender in the disposition of albendazole metabolites in humans.

The pharmacokinetics of albendazole in different single oral doses (400 mg, 800 mg & 1200 mg) was studied and compared in healthy male and female human volunteers using a double-blind design. The serum levels of albendazole main metabolites (albendazole sulphoxide and albendazole sulphone) were analysed using a modified high-pressure liquid chromatography method. For both metabolites, there was no significant difference in the biological half-life ( t(1/2)), time to reach peak concentration (t(max)) and mean residence time (MRT) between men and women, whereas apparent oral clearance (Cl(p)/F) and apparent distribution volume (V(d)/F) were less and serum peak concentration (C(max)), area under the serum concentration-time curve (AUC) and area under the first moment curve (AUMC) were more in women than in men. These observations indicate sex dimorphism in pharmacokinetics of albendazole (observed for albendazole sulphoxide and albendazole sulphone) which were explained on the basis of a change in fraction of the main drug turned to metabolite as a result of more extensive first-pass metabolism of the main drug in the liver of adult female subjects.