Ivermectin pharmacokinetics in horses organism after the application of Equiverm antiparasitic paste

The purpose of the research: study of Ivermectin pharmacokinetics in horses organism after the application of Equiverm antiparasitic paste. Materials and methods. For studying of pharmacokinetics of Equiverm in blood plasma of five manorial breed horses at the age of 6-7 years, with the weight about 400-450 kg antiparasitic paste was injected orally by syringe dispenser in an amount of 0.2 mg/kg body weight, and then blood sampling from jugular vein was performed in 1, 2, 3, 5, 7 ,9, 24, 48, 96, 144, 288, 456, 624, 720 hours for the following determination of the concentration of Ivermectin in blood plasma of horses by high pressure liquid chromatography with ultra-violet detection using P.K. Sanyal method (1994). Validated method of determination Ivermectin in blood serum of was developed. It allows determining this analyte in extremely low concentrations (LOD value is 0.03 ng/mL, LOQ value is 0.09 ng/mL). Results and discussion. Ivermectin is absorbed in horses digestive tract after oral administration and it reaches defined blood serum concentrations in 1-2 hours after oral administration of antiparasitic paste - 0.2 ng/mL. Maximum concentration of 0.84 ng/mL was registered in 7 hours, and Ivermectin level decreased gradually to 0.2 ng/mL by the fourth day. Therefore, upon oral administration of Equiverm antiparasitic paste ivermectin was absorbed well enough and it enters the systemic circulation where it circulates during 4 days. Only trace amounts of Ivermectin are determined two weeks after drug administration.