Pharmacokinetic study of ofloxacin enantiomers inPagrosomus majorby chiral HPLC

(S)-(-)-Ofloxacin and (R)-(+)-ofloxacin concentrations in the plasma of Pagrosomus major after drug treatment were detected by chiral high-performance liquid chromatography, and various pharmacokinetic parameters were calculated from these data. The elimination half-life of (S)-(-)-ofloxacin was significantly shorter than that of the (R)-(+) enantiomer. (S)-(-)-Ofloxacin also had a significantly lower maximum plasma concentration, area under the concentration-time curve from zero to infinity, and mean residence time than (R)-(+)-ofloxacin. However, the apparent volume of distribution and total body clearance of (S)-(-)-ofloxacin were greater than those of (R)-(+)-ofloxacin. The ratio of the (S)-(-)- to (R)-(+)-ofloxacin plasma concentration was always <1.0. Together, these data suggest that (S)-(-)-ofloxacin was preferentially excreted and (R)-(+)-ofloxacin was preferentially absorbed. Although the difference in pharmacokinetic parameters was small, the metabolic behavior of the ofloxacin enantiomers in P. major was enantioselective.