Effects of diet and species on the pharmacokinetics of fenbendazole in cattle.

摘要

The plasma concentration profiles of fenbendazole (FBZ), FBZ-sulfoxide (OFZ) and FBZ-sulfone were measured following intraruminal administration of FBZ (Panacur) at 7.5 mg/kg body weight in 4 castrated male Hereford cattle and 4 castrated male Brahman zebu of approximately 10 months of age at the start of the experiment. FBZ was administered on 3 occasions with 17 and 18 weeks between treatments. The first treatment was given while the animals were fed a diet of 100% wheaten chaff, the second whiletheir diet consisted of 50% wheaten chaff and 50% lucerne and the third while they were fed on 100% lucerne. There were no differences between the species except for a longer time to peak plasma concentration for OFZ in the cattle fed 100% wheaten chaff. Cattle fed wheaten chaff alone gave greater areas under the concentration-time curve and longer persistence for all metabolites than when the same cattle were fed the other diets. It is concluded that the reduced rate of passage of digesta on lower-quality fibrous diets allows greater time for absorption of FBZ and its metabolites from the gut, thereby increasing systemic availability.