Pharmacokinetics of (S)-ornidazole and (S)-ornidazole phosphate disodium in rats

The aims of this study were to conduct the comparative evaluation of pharmacokinetic of (S) - ornidazole [(S)-ONZ] and (S)-ornidazole phosphate disodium [(5) ONZ-P] in rats, and to observe the potential chiral transformation to (R)-ornidazole [(R)-ONZ] using developed LC-MS/MS method. After single, intravenous administration of 25,50,100 mg/kg (S)-ONZ and(S)-ONZ-P [equal molarity to that of (S)-ONZ], it was found that there existed linearity between the calculated areas under the curve (AUC₀.") and dose. And elimination half-time (t,_1/2) of (S)-ONZ was calculated to be 2.04-2. 31 h and 2.02-2.51 h, respectively. After iv dosing of (S)-ONZ-P, (S)-ONZ-P quickly transferred into (S)-ONZ with the average transformation time of around 1.57 to 3.86 min. No significant differences in pharmacokinetics between the two drugs were found in rats. There was no (R)-ONZ detected in the plasma using both (S)-ONZ and (S)-ONZ-P.