Influence of cefoperazone and azithromycin on the pharmacokinetics of pazufloxacin in rats.

The effects of cefoperazone and azithromycin administered separately on the pharmacokinetics of pazufloxacin (PZFX) mesilate were investigated in rats. Animals were injected with cefoperazone at a high dose (180 mg/kg) or azithromycin at a dose of 45 mg/kg through the tail vein 10 min before intravenous (i.v.) administration of PZFX (45 mg/kg). Blood concentrations of PZFX were determined by HPLC. Parameters relating to the pharmacokinetic interaction between PZFX and cefoperazone or azithromycin were estimated by a two-compartmental model. The experimental results showed that the presence of azithromycin significantly delayed the t(1/2 beta) and mean residence time (MRT) of PZFX in the plasma. However, no significant changes between the control group and the cefoperazone-treated animals in the pharmacokinetic parameters of PZFX, such as t(1/2 beta), volume of distribution (Vd), area under the curve (AUC) and the clearance (Cl) were observed.