Investigation of chiral inversion and pharmacokinetics of laevo-ornidazole by high-performance liquid chromatography

What is known and Objective: Laevo-ornidazole is an enantiomer of ornidazole, a 5-nitroimidazole antimicrobial agent. It is not known whether chiral inversion of laevo-ornidazole occurs in humans. The objective of this study was to investigate the possible chiral inversion and pharmacokinetics of the drug in vivo. Methods: We developed a stereo-specific high-performance liquid chromatographic method for investigating chiral inversion of the drug and a standard high-performance liquid chromatography (HPLC) for the routine assay of the drug in pharmacokinetic studies. We report on the pharmacokinetics of the drug following single dose and multiple doses and investigate the effect of food in healthy volunteers. Results and Discussion: There was no chiral inversion of laevo-ornidazole in vivo. In the pharmacokinetic study of the drug in healthy Chinese volunteers, food intake affected the absorption rate of laevo-ornidazole but not the extent. What is new and Conclusion: We present the first reported method for the chiral separation of ornidazole in human plasma. We demonstrate the absence of chiral inversion of laevo-ornidazole in vivo. Given the absence on in vivo chiral inversion, we also report and validate a simplified non-chiral method for the determination of laevo-ornidazole. We show that although food can affect the absorption rate of laevo-ornidazole, the extent was unaffected.