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.