THE EFFECT OF FEED QUALITY ON THE KINETIC DISPOSITION OF ORALLY-ADMINISTERED TRICLABENDAZOLE IN SHEEP

The effect of two qualities of feed on the kinetic disposition of tric labendazole (TCBZ) metabolites was investigated in sheep (n = 4) follo wing oral administration of TCBZ at 10 mg/kg body weight. The same she ep were given sequentially two qualitatively different diets: a low-qu ality (LQ) diet based on wheat straw nd libitum, and a high-quality (H Q) diet based on barley+alfalfa. The triclabendazole sulphoxide (TCBZS O) and triclabendazole sulphone (TCBZSO(2)) concentrations were determ ined in blood samples taken serially from the jugular vein between 5 m in and 9 days after TCBZ administration. The parent drug TCBZ was not detected in any of the samples. The quality of feed affected the kinet ics of both TCBZ metabolites. The rate of appearance (T-lag and T-max) in the jugular blood was slower and the formed amount (AUC) of TCBZSO was slightly higher when the sheep were on the LQ diet (T-lag = 7.74 h; T-max = 27.91 h; AUC = 1042 mu g.h/ml) than when they were offered the HQ diet (T-lag = 1.90 h; T-max = 16.01 h; AUC = 832.4 mu g.h/ml). The MRT of TCBZSO was about 40% longer with the LQ diet than with the HQ diet. Similarly, the rate of appearance of TCBZSO(2) in plasma of s heep was slower when they were on the LQ diet than when they were on t he HQ diet, suggesting an impairment of the hepatic enzymatic activity involved in the oxidation of TCBZSO to TCBZSO(2).