RESIDUE DEPLETION STUDIES ON DANOFLOXACIN IN THE CHICKEN

Penetration of danofloxacin into tissues is consistent-with oral bioavailability and pharmacokinetic plasma data derived from chickens given danofloxacin by iv bolus and oral gavage administration at 5 mg/kg. This pharmacokinetic assessment was confirmed when [H-3]danofloxacin was administered to broilers in drinking water at 25 mu g/mL for 5 days, and tissues were assayed for residues. Under this regimen, total residues of danofloxacin were higher in liver than other tissues and declined in liver from 0.612 mu g/g at 6 h to 0.056 mu g/g by 48 h of withdrawal, suggesting rapid depletion. In kidney and muscle total residues depleted in parallel with liver but were 2- and 10-fold lower, respectively. The major residue in all tissues was unchanged danofloxacin. An N-demethyl metabolite was found in liver and excreta but was not detected in muscle or fat/skin, indicating that it is an excretory metabolite. The depletion of unchanged and N-demethyl metabolite residues from edible tissues of the chicken was confirmed by HPLC with fluorescence detection when danofloxacin was given to 3-week-old chickens under a commercial use condition, i.e., in drinking water for 3 days at 5 mg/kg of body weight per day.