Characterization of ornidazole metabolites in human bile after intraveneous doses by ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry

Abstract

Ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) was used to characterize ornidazole metabolites in human bile after intravenous doses. A liquid chromatography tandem mass spectrometry (LC–MS/MS) assay was developed for the determination of the bile level of ornidazole. Bile samples, collected from four patients with T-tube drainage after biliary tract surgery, were prepared by protein precipitation with acetonitrile before analysis. A total of 12 metabolites, including 10 novel metabolites, were detected and characterized. The metabolites of ornidazole in human bile were the products of hydrochloride (HCl) elimination, oxidative dechlorination, hydroxylation, sulfation, diastereoisomeric glucuronation, and substitution of NO2 or Cl atom by cysteine or N-acetylcysteine, and oxidative dechlorination followed by further carboxylation. The bile levels of ornidazole at 12h after multiple intravenous infusions were well above its minimal inhibitory concentration for common strains of anaerobic bacteria.