Influence of Pasteurella multocida infection on the pharmacokinetic behavior of marbofloxacin after intravenous and intramuscular administrations in rabbits.

The pharmacokinetic behavior of marbofloxacin was studied in healthy (n = 12) and Pasteurella multocida infected rabbits (n = 12) after single intravenous (i.v.) and intramuscular (i.m.) administrations. Six rabbits in each group (control and diseased) were given a single dose of 2 mg/kg body weight (bw) of marbofloxacin intravenously. The other six rabbits in each group were given the same dose of the drug intramuscularly. The concentration of marbofloxacin in plasma was determined using high-performance liquid chromatography. The plasma concentrations were higher in diseased rabbits than in healthy rabbits following both routes of injections. Following i.v. administration, the values of the elimination half-life (t(1/2beta)), and area under the curve were significantly higher, whereas total body clearance was significantly lower in diseased rabbits. After i.m. administration, the elimination half-life (t(1/2el)), mean residence time, and maximum plasma concentration (C(max)) were higher in diseased rabbits (5.33 h, 7.35 h and 2.24 microg/mL) than in healthy rabbits (4.33 h, 6.81 h and 1.81 microg/mL, respectively). Marbofloxacin was bound to the extent of 26 +/- 1.3% and 23 +/- 1.6% to plasma protein of healthy and diseased rabbits, respectively. The C(max)/MIC (minimum inhibitory concentration) and AUC/MIC ratios were significantly higher in diseased rabbits (28 and 189 h) than in healthy rabbits (23 and 157 h), indicating the favorable pharmacodynamic characteristics of the drug in diseased rabbits.