EFFECTS OF EXPERIMENTALLY INDUCED COLIBACILLOSIS ON THE PHARMACOKINETICS OF OFLOXACIN IN CHICKENS

Abstract

Colibacillosis was produced experimentally in 14 white Leghorn broiler chickens by intratracheal inoculation of 0.3 ml broth of E. coli O78:K80 containing approximately 106 colony forming unit. Another 7 clinically normal chickens were used in this study. Ofloxacin was administered to chickens intravenously and orally (5 mg/kg b.wt.) to determine the effect of colibacillosis on its kinetic behavior. The concentration of ofloxacin in serum samples collected at presche-duled time were estimated by using microbiological assay. The phar-macokinetic parameters were determined by two compartment open model. The drug concentration (≥ 0.1 µg/ml) was maintained up to 24 h. There were statistically (P<0.05) significant differences between normal and colibacillosed chickens represented by half-time of elimin-ation,transfer rate constants,elimination rate constant,apparent volume of the central compartment and body clearance of the drug following intravenous administration. Following oral administration the absorp-tion rate constant, absorption half-life and the time needed to reach the maximum concentration were statistically (P<0.05) significantly diffe-rent between normal and colibacillosed chickens. The bioavailability of ofloxacin in normal chickens following oral administration was found to be 91.9 ± 8.25%. The in vitro protein binding of ofloxacin in normal chicken serum at different concentrat-ions was 15.98 ± 0.92%. Based on these kinetic parameters clinical application of ofloxacin at a dose of 5 mg/kg at 24 h dosing interval by intravenous or oral administration in chickens is recommended.