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 mu g/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.