Ornidazole: comprehensive profile

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 (Cmax), time to Cmax (Tmax), the area under the curve (AUC) from t = 0 to infinity (AUC0-∞), AUC from t = 0 to the last quantifiable concentration (AUC0-t), half-life (t1/2), 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 AUC0-t, Cmax, and AUC0-∞ 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 AUC0-t, Cmax, and AUC0-∞ 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 (Cmax, AUC0-72, and AUC0-∞) 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.

Kinetic constants and transformation products of ornidazole during ozonation

Ornidazole (ONZ), a nitroimidazole antibiotic detected in water bodies, may negatively impact the aquatic ecosystem. Its reaction kinetics during ozonation which is a feasible and applicable technology to control the contamination of emerging contaminants, however, has not been reported in literature. In this study, we measured the apparent second-order kinetic constant of ONZ with ozone molecules via the excessive ozone method and the competing method which led to an average value of 103.8 ± 2.7 M-1 s-1 at pH 7. The apparent second-order kinetic constant of ONZ with HO• was calculated to be 4.65 × 109 M-1 s-1 with the concept of Rct measured via para-chlorobenzoic acid as a probe. The transformation products (TPs) of ONZ during ozonation at pH 3 and pH 11 were separately analyzed with HPLC-MS/MS and some unique products were found at pH 11, reflecting the influence of HO•. The toxicity of individual TPs was predicted with the tool of T.E.S.T. It was found that 62% of 21 identified TPs could be more toxic than ONZ in terms of at least one acute toxicity endpoint, including chlorinated amines and N-oxides. The analysis with a respirometer further revealed that the toxicity of mixing TPs generated at HO• rich conditions was slightly lower than O3 dominated conditions. In general, this study provides the basic kinetic data for designing ozonation processes to eliminate ONZ and the important reference for understanding the toxicity evolution of ONZ during ozonation.

Green synthesis, characterization, and antimicrobial applications of silver nanoparticles as fluorescent nanoprobes for the spectrofluorimetric determination of ornidazole and miconazole

A green and simple method was proposed for the synthesis of silver nanoparticles (Ag-NPs) using Piper cubeba seed extract as a reducing agent for the first time. The prepared Ag-NPs were characterized using different spectroscopic and microscopic techniques. The obtained Ag-NPs showed an emission band at 320 nm when excited at 280 nm and exhibited strong green fluorescence under UV-light. The produced Ag-NPs were used as fluorescent nanosensors for the spectrofluorimetric determination of ornidazole (ONZ) and miconazole nitrate (MIZ) based on their quantitative quenching of Ag-NPs native fluorescence. The current study introduces the first spectrofluorimetric method for the determination of the studied drugs using Ag-NPs without the need for any pre-derivatization steps. Since the studied drugs don't exhibit native fluorescent properties, the importance of the proposed study is magnified. The proposed method displayed a linear relationship between the fluorescence quenching and the concentrations of the studied drugs over the range of 5.0-80.0 µM and 20.0-100.0 µM with limits of detection (LOD) of 0.35 µM and 1.43 µM for ONZ and MIZ, respectively. The proposed method was applied for the determination of ONZ and MIZ in different dosage forms and human plasma samples with high % recoveries and low % RSD values. The developed method was validated according to ICH guidelines. Moreover, the synthesized Ag-NPs demonstrated significant antimicrobial activities against three different bacterial strains and one candida species. Therefore, the proposed method may hold potential applications in the antimicrobial therapy and related mechanism research.

In Vivo Inhibitory Assessment of Potential Antifungal Agents on Nosema ceranae Proliferation in Honey Bees

Nosema ceranae Fries, 1996, causes contagious fungal nosemosis disease in managed honey bees, Apis mellifera L. It is associated around the world with winter losses and colony collapse disorder. We used a laboratory in vivo screening assay to test curcumin, fenbendazole, nitrofurazone and ornidazole against N. ceranae in honey bees to identify novel compounds with anti-nosemosis activity compared to the commercially available medication Fumagilin-B®. Over a 20-day period, Nosema-inoculated bees in Plexiglas cages were orally treated with subsequent dilutions of candidate compounds, or Fumagilin-B® at the recommended dose, with three replicates per treatment. Outcomes indicated that fenbendazole suppressed Nosema spore proliferation, resulting in lower spore abundance in live bees (0.36 ± 1.18 million spores per bee) and dead bees (0.03 ± 0.25 million spores per bee), in comparison to Fumagilin-B®-treated live bees (3.21 ± 2.19 million spores per bee) and dead bees (3.5 ± 0.6 million spores per bee). Our findings suggest that Fumagilin-B® at the recommended dose suppressed Nosema. However, it was also likely responsible for killing Nosema-infected bees (24% mortality). Bees treated with fenbendazole experienced a greater survival probability (71%), followed by ornidazole (69%), compared to Nosema-infected non-treated control bees (20%). This research revealed that among screened compounds, fenbendazole, along with ornidazole, has potential effective antifungal activities against N. ceranae in a controlled laboratory environment.

Homochiral Eu3+@MOF Composite for the Enantioselective Detection and Separation of (R/S)-Ornidazole

The development of homochiral materials for the enantioselective detection and separation of chiral drugs is in high demand for the pharmaceutical industry. Herein, an anionic homochiral metal-organic framework (HMOF) with in situ generated [Me₂NH₂]⁺ counterions, {[Me₂NH₂]₂[Zn₂(d-L)₂(HCO₂)(OH)]·5H₂O}_n (HMOF-1), was synthesized using a d-camphorate-derived enantiopure dicarboxylate ligand, 4,4'-[[(1R,3S)-1,2,2-trimethylcyclopentane-1,3-dicarbonyl]bis(azanediyl)]dibenzoic acid (d-H₂L) via a simple solvothermal method. Interestingly, HMOF-1 could be used as a parent framework to encapsulate Eu³⁺ cations via an ion-exchange process, yielding an Eu³⁺@HMOF-1 composite with dual-luminescent centers. The obtained Eu³⁺@HMOF-1 has high chemical stability and good luminescence stability in water. Importantly, Eu³⁺@HMOF-1 exhibits enhanced enantioselectivity and sensitivity in the detection of an important chiral nitroimidazole antibiotic, (R/S)-ornidazole (ONZ) in comparison to HMOF-1 under the same aqueous conditions. The enantiomeric excess (ee) value of the ONZ enantiomers can be accurately determined by the ratio of dual emission from the ligand and Eu³⁺. In addition, Eu³⁺@HMOF-1 shows the enantioselective separation of racemic ONZ enantiomers with an ee value of 86.6%. This work provides a simple strategy for the preparation of Ln^III-incorporated HMOF composite materials for the simultaneous enantioselective detection and separation of chiral drugs.

Kinetics of bactericidal potency with synergistic combination of allicin and selected antibiotics

Synergistic therapy against the resurgence of bacterial pathogenesis is a modern trend for antibacterial chemotherapy. The phytochemical allicin, found in garlic extract is a commendable antimicrobial agent that can be used in synergistic combination with modern antibiotics. Determination of optimal antibacterial combination for the target species is vital for maximizing efficacy, lowering toxicity, total eradication of the bacterial cells and minimization of the risk of resistance generation. In this present investigation, Hill function-based pharmacodynamics models were employed to elaborate various time-kill kinetics parameters. The bactericidal potency of the synergistic combinations of allicin and individual antibiotic was assessed in comparison to their monotherapy application viz. using sole allicin and sole antibiotics (levofloxacin, ciprofloxacin, oxytetracycline, rifaximin, ornidazole and azithromycin) on actively growing Bacillus subtilis and Escherichia coli bacteria. Here, all the synergistic combinations showed significantly better (t-test p-value < 0.05) killing effect and biofilm reduction potential compared to their respective monotherapy application, where the highest killing effect was observed with rifaximin-allicin combination (kill rate was more than 5.5 h^-1). Moreover, the average inhibition potential to protein denaturation by the synergistic combination group was significantly higher (3.4 fold) than the sole antibiotic's group manifests reduction in the dose-related toxicity. The potential of synergism between antibiotics and allicin combination demonstrated greater killing efficiency at significantly lower concentration compared to monotherapy with increased kill rates in all cases.

Decomposition of antibiotic ornidazole by gamma irradiation in aqueous solution: kinetics and its removal mechanism

An efficient gamma radiolytic decomposition of one of the extensively used pharmaceutical ornidazole (ORZ) was explored under different experimental conditions by varying initial concentrations, solution pHs, and doses and concentrations of inorganic ([Formula: see text]) and organic (t-BuOH) additives. The results showed that low ORZ concentrations could be efficiently decomposed using gamma irradiation. The decomposition was followed by pseudo first-order reaction kinetics with rate constant values of 2.34, 1.48, 1.11, and 0.80 kGy^-1 for the following initial concentrations: 25, 50, 75, and 100 mg L^-1 with their corresponding (G(-ORZ)) values of 1.004, 1.683, 2.237, and 2.273, respectively. Decomposition rate of ORZ was remarkably improved under acidic condition when compared to neutral or alkaline medium. It was also observed that the decomposition was primarily caused by the reaction of ORZ with radiolytically generated reactive HO^• radicals. The addition of H₂O₂ had a synergistic effect on the decomposition and mineralization extent of ORZ. However, the removal of total organic carbon (TOC) was not as effective as the decomposition of ORZ. Finally, the quantum chemical calculations were employed to optimize the geometry structure of ORZ and liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) was used to identify the decomposition intermediates. On the basis of Gaussian calculations and analysis of LC-QTOF-MS, it can be inferred that ORZ radiolytic decomposition was mainly attributed to oxidative HO^• radicals and the direct cleavage of ORZ molecules. Possible pathways for ORZ decomposition using gamma irradiation in aqueous medium were proposed.

Simultaneous determination of ornidazole and its main metabolites in human plasma by LC–MS/MS: application to a pharmacokinetic study

Background: Ornidazole is a 5-nitroimidazole antimicrobial agent used for almost 40 years. A novel LC–MS/MS assay was developed and validated for the simultaneous determination of ornidazole and its main metabolites (M3, M6, M16–1, and M16–2) in human plasma. Results: After extraction from 100 μl of plasma by protein precipitation with acetonitrile, all the analytes were separated on a Capcell PAK MG C18 column (100 × 4.6 mm, 5 μm) within 5.0 min and detected by ESI-MS/MS in the positive mode. The validation results met the acceptance criteria as per the US FDA and EMA guidelines. Conclusion: The validated method was successfully applied to a pharmacokinetic study after oral administration of 1000 mg ornidazole to six healthy Chinese volunteers.