Disposition kinetics and tissue residues of danofloxacin in Muscovy ducks

1. The disposition kinetics and plasma availability of danofloxacin in Muscovy ducks after single intravenous (i.v.), intramuscular (i.m.) and oral administrations of 5 mg/kg body weight were investigated. 2. Tissue residue profiles (liver, kidney and muscle) and plasma were also studied after multiple intramuscular and oral administration of 5 mg/kg 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 vs. 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)) 0.08 h and (t(1/2beta)) 3.91 h for distribution and elimination phases, respectively. 5. After intramuscular and oral administration of danofloxacin at the same dose the peak plasma concentrations (C(max)) were 0.89 and 0.81 microg/ml and attained at 1.17 and 1.21 h (T(max)), respectively, and the elimination half-lives (T(1/2el)) were 2.91 and 2.39 h, respectively. The systemic bioavailabilities were 103.21 and 89.26%, following i.m. and oral admisistartion, respectively. In vitro protein binding percent of danofloxacin in Muscovy ducks plasma was 17%. 6. The tissue level following i.m. and oral administration were highest in liver and kidney, respectively, and decreased in the following order: plasma and muscle. No danofloxacin residues were detected in tissues and plasma after 96 h with either route of administration except in liver and kidney, after 120 h in case of oral administration.