Determination of orbifloxacin in sheep plasma by high performance liquid chromatography with ultraviolet detection after intravenous and intramuscular administration.

INTRODUCTION: Single-dose pharmacokinetics of orbifloxacin (2.5mg/kg body weight) were determined in clinically normal female Patanwadi sheep (n=6) following intravenous and intramuscular administration. METHODS: Orbifloxacin concentrations were determined by high performance liquid chromatography with ultraviolet detection. The concentration-time data were analyzed by non-compartmental kinetic method. RESULTS AND DISCUSSION: Following a single intravenous injection, an elimination half-life (t(1/2ß)) of 8.31±0.102h. Steady-state volume of distribution (Vd(ss)) and total body clearance (Cl(B)) were 3.09±0.282L/kg and 0.158±0.006L/kg/h, respectively. Following intramuscular administration, an elimination rate constant (ß), the area under the curve from zero to infinity (AUC(0-∞)) and the mean absorption time (MAT) were 0.015±0.001h(-1), 23.49±1.722µg·h/mL and 7.50±0.58h, respectively. The peak plasma concentration (C(max)) of 1.81±0.005µg/mL was achieved at 1.00±0.00h. The mean residence time (MRT) was 26.25±1.083h and the absolute bioavailability was 150.8±12.35%, respectively. Orbifloxacin could be useful for the treatment of bacterial infections in sheep that are sensitive to this drug.

Plasma disposition of conventional and long-acting moxifloxacin in sheep after intravenous administration.

This study describes disposition of long-acting moxifloxacin and conventional formulations of moxifloxacin in sheep after intravenous administration in five male sheep. Long acting moxifloxacin solution (10% moxifloxacin in solution with L-arginine, N-butyl alcohol, and benzyl alcohol) and conventional moxifloxacin (10%) were injected in jugular vein. Blood samples were collected from contralateral jugular vein in test tubes containing 30-50 IU heparin (anticoagulant) periodically from 0.083 to 72 h of drug administration. Drug concentrations in plasma were determined using High-Performance Liquid Chromatography (HPLC) with fluorescence detector. The mobile phase consisted of a mixture of buffer (10 gm of tetrabutyl ammonium hydrogen sulphate per liter-deionised water) and acetonitrile (80 : 20). The buffer was 0.067M of disodium hydrogen phosphate with pH of 7.5. The flow rate was 1 mL·min(-1) at ambient temperature. The effluent was monitored at 296 nm excitation and 504 nm emissions wavelength. HPLC with fluorescence detector method for plasma moxifloxacin assay was standardized with specific modification for plasma of sheep in the present study. After single-dose intravenous administration of long acting moxifloxacin the plasma concentration of 0.016 ± 0.001 µ g·mL(-1) was maintained for up to 72 h. Conventional formulation of moxifloxacin remained in body for up to 24 h of drug administration with the level of 0.015 ± 0.005 µ g·mL(-1).