The Investigation of Bioequivalence of Some Enrofloxacin Preparations Following Oral Administration In Broilers

This study evaluated the bioequivalence of three different enrofloxacin preparations in broilers after oral administration. Forty male broilers (Ross 308 broiler breeders) fed with feed containing no residues of drugs and pollutants for 30 days were used in the study. They were divided into four experimental groups each consisting of 10 animals. Enrofloxacin active substance solution, Reference Drug, Test Drug 1, and Test Drug 2 were administered to Group 1, Group 2, Group 3, and Group 4, respectively. Intravenous (IV) administration was performed in Group 1 whereas Groups 2, 3, and 4 received oral gastrointestinal administration at a dose of 10 mg/kg using a probe. A blood sample of 1.0–2.0 mL was collected from the animals through v.cutanea ulnaris into sterile heparinized tubes before the drug administration (0.0 min) and at 0.5th, 1st, 2nd, 4th, 8th, 12th, 18th, 24th, 36th, and 48th hours after drug administration starting at 5th minute in Group 1 and 0.25th hour in other groups. Blood plasma was separated into its own fractions. Following the extraction of enrofloxacin and ciprofloxacin from plasma, measurements were made using high-performance liquid chromatography (HPLC). Danofloxacin active substance was used as an internal standard (IS) in the extraction stage. Tests were performed for the sensitivity and reproducibility of the extraction method. Accordingly, HPLC showed that the time for plasma drug concentration to reach the peak value was 11.9–12.8th minutes for enrofloxacin, 8.4–9.2th minutes for ciprofloxacin, and 10.4–11.2th minutes for danofloxacin. The sensitivity of the method was determined as 0.01 µg/mL for enrofloxacin and 0.04 µg/mL for its metabolite ciprofloxacin and the recovery value of the method was found to be 75–90% for enrofloxacin and 55–70% for ciprofloxacin.  In the determination of bioequivalence, values obtained by dividing the area under the curve (AUC) of the test drug 1 and test drug 2 and plasma peak plasma concentration (Cmax) into the reference drug (0.96 and 0.97, respectively for the AUC and 0.92 and 0.97, respectively for Cmax) were found to be within acceptable limits (0.80–1.25).