Pharmacokinetics of a novel formulation of ivermecti n after administration to goats

P. 323-328Objective-To evaluate the pharmacokinetics of a novel commercial formulation of ivermectin after administration to goats . Animals-6 healthy adult goats. Procedure-lvermectin (200 µg/kg) was initially administered IV to each goat, and plasma samples were obtained for 36 days. After a washout period of 3 weeks, each goat received a novel commercial for­ mulation of ivermectin (200 µg/kg) by se injection. Plasma samples were then obtained for 42 days. Drug concentrations were quantified by use of high­ performance liquid chromatography with fluores­ cence detection. Results-Pharmacokinetics of ivermectin after IV administration were best described by a 2-compart­ ment open model; values for main compartmental variables included volume of distribution at a steady state (9.94 L/kg), clearance (1.54 L/kg/d), and area under the plasma concentration-time curve (AUC; 143 [ng•dl/ml) . Values for the noncompartmental variables included mean residence time (7.37 days). AUe (153 [ng•dl/ml). and clearance (1.43 L/kg/d). After se administration, noncompartmental pharma­ cokinetic analysis was conducted . Values of the vari­ ables calculated by use of this method included max­ imum plasma concentration (Cmax; 21.8 ng/ml), time to reach Cmax (3 days). and bioavailability (F; 91.8%) . Conclusions and Clinical Relevance-The commer­ cial formulation used in this study is a good option to consider when administering ivermectin to goats because of the high absorption, which is character­ ized by high values of F. In addition, the values of Cmax and time to reach Cmax are higher than those reported by other investigators who used other routes of administration.S