Some pharmacokinetic parameters of eprinomectin in goats following pour-onadministration

Some pharmacokinetic parameters of eprinomectin were determined in goats fo llowing topical application at a dose rate of 0.5 mg/kg. The plasma concent ration versus time data for the drug were analysed using a one-compartment model. The maximum plasma concentration of 5.60 +/- 1.01 ng/ml occurred 2.5 5 days after administration. The area under the concentration-time curve (A UC) was 72.31 +/- 11.15 ng day/ml and the mean residence time (MRT) was 9.4 2 +/- 0.43 days. Thus, the systemic availability of eprinomectin to goats w as significantly lower than that for cows. The low concentration of eprinom ectin in the plasma of goats suggests that the pour-on dose of 0.5 mg/kg wo uld be less effective in this species than in cows. Further relevant inform ation about the optimal dosage and residues in the milk of dairy goats is n eeded before eprinomectin should be used in this species.