Plasma and Tissue Disposition of Moxifloxacin in Japanese Quail ( Coturnix japonica ).

Plasma disposition and depletion of moxifloxacin were investigated in Japanese quail ( Coturnix japonica ) after single intravenous, intramuscular, and oral administration of 5 mg/kg and after intramuscular and oral administration of 5 mg/kg q24h for 5 consecutive days, respectively. Drug concentrations in plasma and tissues were measured by high-performance liquid chromatography with fluorescence detection. After intravenous injection, plasma drug concentration-time curves were best described by a 2-compartment open model. The decline in plasma drug concentration was biexponential with half-lives of 0.3 hours and 2.18 hours for distribution and elimination phases, respectively. Steady-state volume of distribution and total body clearance after intravenous administration were estimated to be 1.12 L/kg and 0.41 L/h per kilogram, respectively. After intramuscular and oral administration of moxifloxacin at the same dose, the peak plasma concentrations were 2.14 and 1.94 µg/mL and were obtained at 1.4 and 1.87 hours, respectively, and the elimination half-lives were 2.56 and 1.97 hours, respectively. The systemic bioavailabilities were 92.48% and 87.94%, respectively. Tissue levels after intramuscular and oral administration were highest in liver and kidneys, respectively, and decreased in the following order: plasma, lungs, and muscle. Moxifloxacin concentrations after intramuscular and oral administration were below the detection limit of the assay in tissues and plasma after 120 hours.