1.The aim of the present study was to determine the PKs of marbofloxacin in beagle dogs after intravenous (i.v.) and intramuscular (i.m.) administration, the ex vivo and in vitro PK/PD indices of marbofloxacin against clinical isolates of Staphylococcus pseudintermedius, and the ex vivo AUC/MIC ratios associated with different levels of antibacterial activity. 2.After i.v. of marbofloxacin (2 mg/kg), the mean ± SEM values of AUC, t1/2β, Vss, and CL were 8.47 ± 3.51 h µg/mL, 8.08 ± 6.25 h, 2.32 ± 1.00 L/kg and 0.23 ± 0.06 L/kg/h and corresponding values after intramuscular injection were 11.37 ± 3.07 h µg/mL, 7.51 ± 3.70, 1.80 ± 0.90 L/kg and 0.17 ± 0.04 L/kg/h. After i.m. administration, a Cmax of 1.76 ± 0.09 µg/mL was achieved at Tmax of 0.47 ± 0.08 h. The ex-vivo AUC/MIC ratios required to produce bacteriostasis, bactericidal action and elimination of S. pseudintermedius were 65.03, 97.02 and 136.84 h. 3.The in vivo AUC/MIC ratios obtained after i.v. and i.m. administration of 2 mg/kg marbofloxacin (67.76 ± 1.23 and 91.18 ± 2.61) were below the ex vivo AUC/MIC ratios required for bactericidal activity and bacterial elimination (97.02 ± 9.24 2 mg/kg and 136.21 ± 7.58), suggesting that the recommended daily dosage (2 mg/kg) may not suffice to kill and eradicate S. pseudintermedius strains encountered in clinical area.
