PLASMA PROFILE STUDY OF MOXIDECTIN IN A COW AND ITS SUCKLING CALF

The plasma concentration of moxidectin, a macrocyclic lactone endectoc ide, was investigated in a cow and its suckling calf, using a new chem ical assay, following subcutaneous injection (0.2 mg/kg) in the cow. T he most striking result was the persistence of moxidectin in the plasm a of the cow (mean residence time: 25.66 days). Moxidectin was also de tected in the plasma of the calf as a result of the excretion of the d rug in the cow's milk and its ingestion by the calf. The cow and calf plasma concentrations and pharmacokinetic parameters showed parallel d isposition of the drug. The suckling calf received about 5% of the dos e from the cow via the milk.