Thesis (M.Sc.) - Cairo University -Faculty of Veterinary Medicine - Department of Veterinary Pharmacology

The serum concentrations and pharmacokinetics of levofloxacin and danofloxacin in broiler chickens was compared following single intravenous (IV) or oral administration at 10 mg/kg of body weight (b.w.). Serum concentrations of levofloxacin and danofloxacin were determined by specific and sensitive high performance liquid chromatography (HPLC) methods. Pharmacokinetic parameter values for both fluoroquinolones were calculated by non-compartmental analysis. Following IV administration, the elimination half-life (T₁/₂{u₀₂₉₉}) was two-fold higher and the mean residence time (MRT) was three-fold higher for danofloxacin compared to levofloxacin. The values for total body clearance (Cl{u0299}) were 13.67 vs. 64.10 ml/min.kg and volume of distribution at steady state (Vdss) were 6.84 vs. 2.47 L/kg. However, area under the serum concentration vs. time curve of levofloxacin was greater than for danofloxacin. Maximum plasma concentration (Cmax) after oral administration was 1.41 and 0.706 og/ml for levofloxacin and danofloxacin, attaining at one and two hours for both drugs, respectively. Systemic bioavailability (F) was 89% for levofloxacin and {u02C2} 100% for danofloxacin. Furthermore, the apparent volume of distribution (V/F) of danofloxacin was (37.92 L/kg) significantly higher than that of levofloxacin (15.40 L/kg). Following oral administration, the Cmax/MIC ratio of 14.11 and 7.10 and AUC/MIC ratio of 108.68 and 58.50 for levofloxacin and danofloxacin, respectively, indicates potential clinical and bacteriological efficacy of levofloxacin. Based on these parameters, a dose of 10 mg/kg b.w. of levofloxacin given orally every 24 h in chickens can maintain effective serum concentrations with bacterial infections with MIC₉₀> 0.1 og/ml

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