Pharmacokinetics, Pharmacodynamics and Local Tolerance at Injection Site of Marbofloxacin Administered by Regional Intravenous Limb Perfusion in Standing Horses

Objective: To evaluate pharmacokinetic-pharmacodynamic variables and local tolerance at injection-site of marbofloxacin administered via regional intravenous limb perfusion (RIVLP) in standing horses. Animals: Adult horses (n=6). Methods: RIVLP were performed with rubber tourniquets applied to the forelimbs of standing sedated horses. Marbofloxacin (0.67mg/kg) was randomly injected in 1 forelimb, with the contralateral limb serving as a control (0.9% NaCl solution). Samples of jugular blood and synovial fluid from the radiocarpal joint of the marbofloxacin-perfused limb were collected before and at intervals after RIVLP for determination of drug concentrations. All injection sites were evaluated before, 24 and 48hours after RIVLP by means of ultrasonographic examination, circumferential measurements and subjective visible inflammation scores by veterinarians unaware of treatment received. Results: No adverse effects associated with the technique or antibiotic were observed. High marbofloxacin concentrations were obtained in the synovial fluid, AUC(INF) was significantly higher in synovial fluid than in plasma (78.64 +/- 49.41 and 2.85 +/- 0.60 mu g h/mL respectively, P = .028). The efficacy indices, AUC(0-24)/MIC90 and C-maxobs/MIC90, predicted a favorable outcome in the treatment of synovial fluid infections caused by enterobacteriaceae and Staphylococcus aureus. After RIVLP, there was no statistically significant difference between marbofloxacin-injected and control limbs for lameness, visual inflammation score, limb circumference, and ultrasonographic appearance of the veins. Marbofloxacin injected limbs had a significantly greater subcutaneous thickness, compared with control limbs. Conclusions: These data suggest that RIVLP of marbofloxacin (0.67 mg/kg) could be a safe and effective method for treatment of infections of the distal portion of the limb for susceptible organisms.