Tropical Journal of Pharmaceutical Research. Vol 17, No 12 (2018):2483-2487

Pharmacokinetics of enantiomers of oxiracetam in rats
Wu-San Wang, Yu-Feng Wen

Purpose: To investigate the differences in pharmacokinetics of S-oxiracetam (S-ORT) and Roxiracetam (R-ORT) in rats.Methods: Sprague-Dawley rats (20) were randomly divided into two groups (ten rats per group), viz, SORT and R-ORT groups. Rats in S-ORT group received 200 mg S-ORT/kg while rats in R-ORT group were given 200 mg R-ORT/kg. Both treatments were given orally, and blood samples were collected at fixed time intervals for analysis. Ultra performance liquid chromatography-electrospray ionizationtandem mass spectrometry (UPLC???ESI-MS/MS) was used for pharmacokinetic analysis. Portions of the rat plasma were also subjected to configurational transformation analysis using normal phase-high performance liquid chromatographic (NP-HPLC) fitted with a Chiral OC column. Blank blood samples from five rats were used for plasma protein binding rate studying.Results: The two enantiomers did not transform into each other after oral administration, and the? concentrations of S-ORT at 1, 1.5 and 2 h were significantly higher than those of R-ORT (p < 0.05). The area under the curve (AUC0-???) and maximum concentration (Cmax) of S-ORT were also significantly larger than those of R-ORT (p < 0.05). There were no stereoselective differences between the two enantiomers.Conclusion: There are significant differences in absorption between two ORT enantiomers, and this may result in different pharmacological effects.Keywords: S-oxiracetam, R-oxiracetam, Configuration, Pharmacokinetics, Rats

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