THE PLASMA KINETICS AND TISSUE DISTRIBUTION OF ENROFLOXACIN AND ITS METABOLITE CIPROFLOXACIN IN THE MUSCOVY DUCK

The disposition and tissue distribution of enrofloxacin and of its mai n metabolite ciprofloxacin were investigated in ducks after oral or in tramuscular administration of a single dose of 10 mg/kg enrofloxacin.. Plasma and tissue concentrations were determined by a HPLC method. Th e peak concentrations of enrofloxacin after intramuscular administrati on (1.67 mu g/ml at 0.9 h) were higher than after an oral dose (0.99 m u g/ml at 1.38 h). The relative bioavailability of enrofloxacin after administration directly into the crop was 68%, while the metabolic con version of enrofloxacin to ciprofloxacin was quite low (< 10%) with bo th routes of administration. High tissue concentrations and high tissu e:plasma concentration ratios were demonstrated for enrofloxacin and c iprofloxacin 24 h after treatment. it was concluded that a dose of 10 mg/kg per day provides serum and tissue concentrations sufficiently hi gh to be effective in the control of many infectious diseases of ducks .