Pharmacokinetics after intravenous, intramuscular and subcutaneous administration of difloxacin in sheep

The disposition kinetics of difloxacin, a fluoroquinolone antibiotic, after intravenous (IV), intramuscular (IM) and subcutaneous (SC) administration were determined in sheep at a single dose of 5 mg/kg. The concentration–time data were analysed by compartmental (after IV dose) and non-compartmental pharmacokinetics method (after IV, IM and SC administration). Plasma concentrations of difloxacin were determined by high performance liquid chromatography with fluorescence detection. Steady-state volume of distribution (Vss) and clearance (Cl) of difloxacin after IV administration were 1.68 ± 0.21 L/kg and 0.21 ± 0.03 L/h kg, respectively. Following IM and SC administration difloxacin achieved maximum plasma concentration of 1.89 ± 0.55 and 1.39 ± 0.14 mg/L at 2.42 ± 1.28 and 5.33 ± 1.03 h, respectively. The absolute bioavailabilities after IM and SC routes were 99.92 ± 26.50 and 82.35 ± 25.65%, respectively. Based on these kinetic parameters, difloxacin is likely to be effective in sheep.