Comparative enantioselectivity in the sulphoxidation of albendazole in man, dogs and rats.

1. H.p.l.c. analyses were performed to investigate the plasma kinetics of albendazole (ABZ), the sulphoxide (SO.ABZ) and sulphone (SO2ABZ) metabolites, as well as the chirality vs time of SO.ABZ, after oral administration to rats, dogs and man of prochiral sulphide antiparasitic drug ABZ. 2. In all three species the initial plasma concentration ratio of the enantiomers, as soon as SO.ABZ could be detected in plasma, was that of a racemate. 3. Subsequently, the ratio (+)/(-) increased linearly with time, reaching values of 13.1 and 9.3 in man and dogs, respectively, while it decreased to 0.6 in rats. 4. The (+) enantiomer represents 80%, 70% and 41% of the area under the curve of the total SO.ABZ in man, dogs and rats, respectively.