Pharmacokinetic and pharmacodynamic evaluations of levofloxacin in broiler chicken

Objective: To evaluate the PK/PD and residue of levofloxacin (L) after IV and oral administration in broiler chickens.Materials Methods: 60 healthy broiler chickens were randomly divided into 3 groups each of 20 (A, B and C). All the groups were administered with 5 mg/kg of L (A and B oral, C IV). Blood samples were withdrawn at different scheduled times for the group A and C, while animals in group B were sub-divided in 5 sub-groups (n=4) and euthanized for organ (liver, kidney, muscle, lung) collections at different times (1, 6, 10, 24, 48 h). L concentrations in blood and tissues were quantified by an HPLC validated method. As pharmacodynamic studies, minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined against E.coli (isolated in clinical broilers). Ex vivo antibacterial activity of levofloxacin against E.coli was evaluated using the time killing method.Results Conclusion: The pharmacokinetic profiles of Lafter oral and IV administrations were almost overlapping in the elimination phase. The oral F% was 124±39. All the tested organs contained quantifiable L concentrations up to 48 hours. The liver was the most contaminated organ then in descending order kidney, lung and muscle. The results of ex vivo growth inhibition curves were consistent with the in vitro time-kill study. Plasma concentration above 8xMIC led to eradication of E.coli. Pharmacokinetic profile of levofloxacin was similar with those in previous studies in chickens and calves. Levofloxacin showed plasma concentration dependent antibacterial activities against clinical E.coli. Administration of levofloxacin at a dose of 5 mg/kg seems to be enough to kill E.coli.