EFFECT OF DIET VARIATIONS ON THE KINETIC DISPOSITION OF OXFENDAZOLE IN SHEEP

Pharmacokinetic parameters of oxfendazole (OFZ) were determined in fiv e sheep submitted to two different feeding regimens: a poor/dry diet b ased on wheat straw ad libitum, and a rich/green diet based on fresh g rass grazed on pasture. Animals were acclimatised to each diet before they were administered OFZ orally at a dose of 5 mg kg(-1) body weight . Blood samples were taken serially between 10 min and 168 h post-admi nistration Plasma concentrations of OFZ and its metabolites (fenbendaz ole (FBZ) and fenbendazole sulphone) were quantified using an HPLC tec hnique. Rates of absorption of OFZ and of formation of FBZ and fenbend azole sulphone were slower with the poor/dry diet; however, the area u nder FBZ plasma concentration vs time curve was higher when sheep were offered the low quality diet, suggesting a shift of OFZ metabolism to wards FBZ formation. (C) 1997 Australian Society for Parasitology. Pub lished by Elsevier Science Ltd.