Evaluation of Ornidazole Tablets Bioequivalence in Chinese Healthy Participants Under Fasted and Fed Conditions Using Pharmacokinetic Parameters

Background and Objective

Ornidazole, the third generation of nitroimidazole derivatives after metronidazole and tinidazole, it exerts both bactericidal and antiprotozoal effects. The purpose of this study was to evaluate the pharmacokinetic and bioequivalence of two ornidazole tablets manufactured by two different manufacturers based on their pharmacokinetic parameters.

Patients and Methods

Fasted and fed healthy Chinese volunteers participated in a randomized sequence, single-dose, open-label, two-period crossover trial. There were 24 participants in both the fed study and the fasted study. Following a 7-day washout period before receiving the alternative formulation, eligible research participants were randomly assigned (1:1) to receive a single dosage of either the reference formulation or the test formulation. Following tablet administration, plasma samples were obtained over 72 h and analyzed using liquid chromatography tandem mass spectrometry (LC–MS/MS) to evaluate ornidazole contents. maximum plasma concentration (C_max), time to C_max (T_max), the area under the curve (AUC) from t = 0 to infinity (AUC_0–∞), AUC from t = 0 to the last quantifiable concentration (AUC_0–t), half-life (t_1/2), and terminal elimination rate constant (z) were evaluated as pharmacokinetic (PK) parameters. The safety evaluation involved adverse events (AEs) incidence and alterations in laboratory tests (hepatic function, blood biochemistry, hematology, and urinalysis) or vital signs (temperature, pulse, and blood pressure).

Results

For the bioequivalence assessment in the fast trial, the prime PK parameters comparison between the reference and test formulation revealed that the GMR (90% CI) values for AUC_0–t, C_max, and AUC_0–∞ were 100.97% (99.12–102.85%), 99.88% (90.63–110.08%), and 101.12% (99.17–103.11%), respectively. For the bioequivalence assessment in the fed trial, the key PK parameters comparison between the reference and test formulations revealed that the GMR (90% CI) values for AUC_0–t, C_max, and AUC_0–∞ were 103.00% (100.94–105.11%), 101.90% (99.63–104.22%), and 102.99% (100.87–105.16%), respectively. The geometric mean ratios (GMRs) for the primary pharmacokinetic parameters (C_max, AUC_0–72, and AUC_0–∞) between the two formulations and the corresponding 90% confidence intervals (CIs) were all within the range of 80.00–125.00% for both the fasting and fed states. Both treatments have comparable safety profiles.

Conclusion

The bioequivalence and tolerability of ornidazole tablet reference and test formulations were evaluated among healthy Chinese participants under both fasting and fed conditions. The results indicated that both formulations were bioequivalent and generally well tolerated; besides, the interaction between food and drug may affect drug pharmacokinetics.

Trial Registration

CTR20212873, registered on 15 November 2021; ChiCTR2300069098, registered on 7 March 2023.