Bioavailability of a commercial formulation of ivermectin after subcutaneous administration to sheep

Abstract

Objective-To evaluate bioavailability and other pharmacokinetic variables of a commercial formulation of ivermectin after IV administration to sheep. Animals-6 healthy adult sheep. Procedures-A single dose of a commercial formulation of ivermectin (200 µg/kg) was administered IV to each sheep. After a washout period of 3 weeks, each sheep was administered ivermectin by Se injection. Plasma samples were obtained for up to 36 and up to 42 days after IV and se administration, respectively. lvermectin concentrations were quantified by use of high-performance liquid chromatography with fluorescence detection. Results-Results obtained indicated that after IV administration, ivermectin is cleared slowly from plasma, tends to distribute and accumulate in the peripheral compartment, and is slowly eliminated from the body. After se administration, noncompartmental analysis revealed that bioavailability of ivermectin is nearly complete (98.20%), has a slow mean absorption time of 0.96 days, and reaches a maximum plasma concentration of 19.55 ng/ ml at 3.13 days. Conclusions and Clinical Relevance-The commercial formulation of ivermectin used in this study can be administered se to sheep on the basis of a nearly complete bioavailability. Inaddition, the maximum plasma concentration and interval from se injection until maximum plasma concentration is obtained are higher than those reported by other authors who used other routes of administration.