Liver microsomal biotransformation of albendazole in deer, cattle, sheep and pig and some related wild breeds

Albendazole (ABZ) biotransformation was studied in vitro in liver microsomes of adult noncastrated male farm animals (ram, buck, bull and boar), castrated adult males (wether, billy and hog), and free living males (fallowbuck, red deer stag, mouflon ram, roe buck and wild boar). Liver microsomal fractions were incubated with either ABZ or racemic albendazole sulphoxide (ABZSO). ABZ was extensively metabolized to the (+) and (-) enantiomers of ABZSO, whereas ABZSO underwent a slow oxidation to albendazole sulphone (ABZSO 2 ) in all species. In all species both ABZSO enantiomers were detected. The chiral ratio, (+)-ABZSO/(-)-ABZSO, was greater than one in farm animals, mouflon and wild boar, and less than one in three species of deer. For total ABZ sulphoxidation, deer like species had lower values compared to the other species. Mouflon ram and ram had lower total sulphoxidation rates compared to wethers, as well as ABZ suphoxidation towards (+)-ABZSO. No significant difference occurred comparing ABZSO formation in mouflon ram and ram, but ABZSO 2 formation rate in mouflon ram was higher than in rams and wethers. Roe deer stag, fallow buck and red deer stag did not: differ in both total-ABZSO and (-)-ABZSO synthesis rates and roe deer stag and fallow buck did not differ in synthesis rates of (+)-ABZSO and ABZSO 2 . The bull differed from other species in all metabolites studied, except for red deer stag and boar in (-)-ABZSO synthesis rate. The extent of ABZSO sulphonation to ABZSO 2 in bull microsomes was more than twice that of other species.