The plasma levels and milk excretion of eprinomectin were determined in goa
ts following topical application at doses of 0.5 mg kg(-1) and 1.0 mg kg(-1
) The area under the concentration-time curve (AUC) was times lower for 0.5
mg kg(-1) (8.24 +/- 3.50 ng day(-1) ml(-1)) than for 1.0 mg kg(-1) (15.68
+/- 8.84 ng day(-1) ml-'), suggesting that the pharmacokinetics of eprinome
ctin in goats is dose independent. The bioavailability of eprinomectin in l
actating compared with non-lactating goats is low. This is probably due to
the physiological status of dairy animals, which present a marked decrease
in body fat. Comparison of the eprinomectin concentrations in the milk and
plasma demonstrated a parallel disposition of the drug with a milk-to-plasm
a ratio of 0.10-0.25. The amount of drug recovered in the milk was 0.3-0.5%
of the total administered dose, In all cases, the maximum level of residue
in milk remained below the maximum acceptable level of 30 ng ml(-1) permit
ted in lactating cattle.