Albendazole-soybean oil emulsion for the treatment of human cystic echinococcosis: evaluation of bioavailability and bioequivalence.

A single 12.5 mg/kg dose of albendazole (Abz) in tablet form (AbzT) followed 2 weeks later by an equivalent dose of Abz emulsified in 30% soybean oil (AbzE) was administered orally 2 h after the first morning meal to 7 male adult patients with cystic echinococcosis caused by Echinococcus granulosus. Serum samples were taken 1, 3, 5, 7, 8, 9, 11, 14, 18, 24, 36, and 48 h post medication from each patient to measure the serum concentrations of albendazole sulfoxide (AbzSOX), the principal bioactive metabolite of Abz. AbzSOX concentrations were measured by reverse phase HPLC. The data were subjected to pharmacokinetic analysis to compare the relative bioavailability and bioequivalence of AbzT and AbzE. The results demonstrated that the mean peak concentrations (C(max)) for AbzT and AbzE were 1.06+/-0.38 mg/l and 1.71+/-0.47 mg/l, respectively; the area under the concentration-time curves (AUC) were 13.24+/-4.93 mg x h/l and 21.01+/-7.54 mg x h/l, respectively. The relative bioavailability of AbzE was F(Flu)=1.59. Two one-sided tests procedure and (1-2 alpha) 90% confidence interval methods were used to evaluate the bioequivalence of AbzE and AbzT. The results demonstrated that the bioavailability of AbzE was greater than AbzT.