Abstract: The pharmacokinetics was investigated and compared in 50 healthy rabbits following single subcutaneous (5 mg/kg body weight) administration of 5 different ivermectin injection. The ivermectin concentrations in plasma samples were determined by HPLC-UV. Pharmacokinetic analysis of plasma drug concentration-time data for ivermectin was carried out with a computer program 3P97. The ivermectin concentration-time data were fitted to one-compartment open model after single subcutaneous administration of ivermectin injection. The main pharmacokinetics parameters(E) were as T_1/2(Ka)(8.10±3.68)h,T_1/2(Ke)(36.34±14.63) h,T_max(22.38±8.63) h,C_max(354.01±57.75) ng/mL,AUC(25843±3029) ng/(mL·h). The statistics analyzed by SPSS results showed there were no significant differences (P>0.05) in T_1/2(Ka),T_1/2(Ke).However, pharmacokinetic of C_max was significant differences (P<0.05). Pharmacokinetics of AUC was higher than others, the results of present studies showed that the ivermectin injection demonstrated rapid absorption, rapid elimination, highly bioavailability. The safety of ivermectin in rabbits indicated that ivermectin injection satisfied clinical requirements cluded that supplementation of bacillus preparation in diets increased the antioxidant capacity and improve intestine microbial flora of layers.

Key words: ivermectin; bioavailability; pharmacokinetics; rabbits