Pharmacokinetics and tissue residues of moxifloxacin in broiler chickens.

1. In this study the disposition kinetics and plasma availability of moxifloxacin in broiler chickens after single intravenous (i.v.), intramuscular (i.m.) and oral (p.o.) administrations of 5 mg/kg body weight were investigated. 2. Tissue residue profiles (liver, kidney, lung and muscle) and plasma were also studied after multiple intramuscular and oral administration of 5 mg/kg body weight, once daily for 5 consecutive days. 3. The concentrations of the drug in the plasma and tissues were measured using high-performance liquid chromatography (HPLC) with fluorescence detection on samples collected at frequent intervals after drug administration. 4. Following intravenous injection, plasma concentration-time curves were best described by a two-compartment open model. The decline in plasma drug concentration was bi-exponential with half-lives of (t(1/2alpha)) 0.26 h and (t(1/2beta)) 2.27 h for distribution and elimination phases, respectively. 5. After intramuscular and oral administration of moxifloxacin at the same dose the peak plasma concentrations (C(max)) were 2.23 and 1.99 microg/ml and were obtained at 1.56 and 1.90 h (T(max)), respectively, and the elimination half-lives (T(1/2el)) were 2.24 and 1.69 h, respectively. 6. The systemic bioavailabilities were 97.11 and 90.01%, respectively. In vitro protein binding percent was 37%. 7. The tissue levels following i.m. and p.o. administration were highest in liver and kidney, respectively, and decreased in the following order: plasma, lung and muscle. No moxifloxacin residues were detected in tissues and plasma after 120 h with both routes of administration, moxifloxacine was found in both the liver and kidney 144 h after i.m. and oral administration.