Elias G, Lee J-S, Hwang M-H, Park Y-S, Cho K-H, Kim Y-H, Park S-C
College of Veterinary Medicine, Kyungpook National University, Daegu, South Korea.
J Vet Pharmacol Ther. 2009 Jun;32(3):219-28. doi: 10.1111/j.1365-2885.2008.01027.x.
The pharmacokinetics and pharmacodynamics of orbifloxacin were studied in six clinically healthy Hanwoo cows after intravenous (i.v.) and intramuscular (i.m.) administration at a dose of 3 mg/kg. Orbifloxacin concentrations were determined by high performance liquid chromatography with fluorescence detection. Steady-state volume of distribution and clearance of orbifloxacin after i.v. administration were 0.92 L/kg and 0.24 L/h x kg, respectively. Following i.m. administration, a slow and complete absorption with absolute bioavailability of 101.4%, and a maximum concentration (C(max)) of 1.17 microg/mL at 1.04 h were observed. The in vitro serum protein binding was 14.76%. The in vitro antibacterial activity of orbifloxacin against a pathogenic strain of Mannheimia haemolytica (M. haemolytica), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was determined. The ex vivo activity of orbifloxacin against M. haemolytica strain was also determined, and these data were integrated with the ex vivo bacterial counts to establish AUC(24h)/MIC values producing bacteriostatic action, bactericidal action and elimination of bacteria. Mean values were 32.7, 51.6 and 102.6 h, respectively. From these data, we predict that orbifloxacin, when administered i.m. at a dosage of 2.5-5 mg/kg once a day, would be effective against bovine pathogens, such as M. haemolytica. Additional studies may be needed to confirm its efficacy in a clinical setting, and to evaluate the penetration of the drug in diseased tissues.
在6头临床健康的韩牛中，以3mg/kg的剂量静脉注射（i.v.）和肌肉注射（i.m.）后，研究了奥比沙星的药代动力学和药效学。通过高效液相色谱-荧光检测法测定奥比沙星浓度。静脉注射后，奥比沙星的稳态分布容积和清除率分别为0.92L/kg和0.24L/h·kg。肌肉注射后，观察到吸收缓慢且完全，绝对生物利用度为101.4%，在1.04小时达到最大浓度（C(max)）1.17μg/mL。体外血清蛋白结合率为14.76%。测定了奥比沙星对溶血曼氏杆菌（M. haemolytica）、大肠杆菌（E. coli）和金黄色葡萄球菌（S. aureus）致病菌株的体外抗菌活性。还测定了奥比沙星对溶血曼氏杆菌菌株的离体活性，并将这些数据与离体细菌计数相结合，以确定产生抑菌作用、杀菌作用和细菌清除的AUC(24h)/MIC值。平均值分别为32.7、51.6和102.6小时。根据这些数据，我们预测，当以2.5 - 5mg/kg的剂量每天肌肉注射一次奥比沙星时，对溶血曼氏杆菌等牛病原体将有效。可能需要进一步的研究来证实其在临床环境中的疗效，并评估该药物在患病组织中的渗透情况。
