A luminescence nanosensor for Ornidazole detection using graphene quantum dots entrapped in silica molecular imprinted polymer.

A luminescence nanosensor has been developed for analysis of Ornidazole in biological samples using graphene-quantum-dot-embedded silica molecular imprinted polymer (GQD-SMIP) as a selective probe for this analyte. The GQD-SMIP was found to possess a strong fluorescent emission at 450 nm upon excitation at 365 nm. This emission was found to linearly quench in the presence of Ornidazole in a concentration range of 0.75 to 30 µM. A detection limit of 0.24 µM was reached using the probe and the sensor was successfully used in the determination of the analyte in plasma samples.

Clinical Pharmacokinetics of Levornidazole in Elderly Subjects and Dosing Regimen Evaluation Using Pharmacokinetic/Pharmacodynamic Analysis.

PURPOSE: Levornidazole, the levo-isomer of ornidazole, is a third-generation nitroimidazole derivative newly developed after metronidazole, tinidazole, and ornidazole. An open-label, parallel-controlled, single-dose study was conducted for the investigation of the pharmacokinetic (PK) profile of levornidazole and its metabolites in healthy elderly Chinese subjects, and for the evaluation of 2 dosing regimens in the elderly. METHODS: Levornidazole was intravenously administered at 500 mg to healthy elderly (aged 60-80 years) or young subjects (aged 19-45 years). The PK profiles of levornidazole and its metabolites in elderly subjects were evaluated and compared with those in the young group. WinNonlin software was used for simulating the PK profile of levornidazole in the elderly population following the dosing regimens of 500 mg BID and 750 mg once daily for 7 days. Monte Carlo simulation was used for estimating the cumulative fraction of response and probability of target attainment of both dosing regimens against Bacteroides spp. RESULTS: The Cmax, AUC0-24, and AUC0-∞ values of levornidazole in the elderly group were 11.98 µg/mL, 131.36 µg·h/mL, and 173.61 µg·h/mL, respectively. The t1/2, CLt, and mean residence time from time 0 to infinity were 12.21 hours, 2.91 L/h, and 16.46 hours. The metabolic ratios of metabolites (M) 1, 2, 4, and 6 were <3.0%, and that of M16 was 17.70%. The urinary excretion values of levornidazole, M1, M2, M4, M6, and M16 over 96 hours were 10.21%, 0.92%, ~0%, 2.69%, 0.54%, and 41.98%. The PK properties of levornidazole and the urinary excretion of all metabolites were not statistically different between the 2 groups. The cumulative fraction of response was >90% against B fragilis and other Bacteroides spp, and the probability of target attainment was >90% when the minimum inhibitory concentration was ≤1 µg/mL, in both groups. IMPLICATIONS: No dosing regimen adjustment is suggested when levornidazole is used in elderly patients with normal hepatic functioning and mild renal dysfunction. The findings from the PK/PD analysis imply that both regimens may achieve satisfactory clinical and microbiological efficacy against anaerobic infections in elderly patients. Chinese Clinical Trial Registry (http://www.chictr.org.cn) identifier: ChiCTR-OPC-16007938.

Effects of the ornidazole enantiomers on the central nervous system: Involvement of the GABAA receptor.

This is the preliminary study of the sedative and muscle relaxation activity of ornidazole enantiomers, which are widely used in the treatment of susceptible protozoal infections and anaerobic bacterial infections. Adverse effects on the central nervous system (CNS) are the main side effects of ornidazole during its clinical application. The aim of this study was to compare the different central inhibitory effects between S-(-) ornidazole and R-(+) ornidazole in mice and clarify the possible mechanisms. In the present study, central effects of ornidazole were evaluated by open-field test and rota-rod test, and such effects were reversed by pre-treatment with flumazenil (i.p., 10 mg/kg) suggesting that ornidazole exhibits such action by interacting with the GABAergic system. Then, the functional difference between S-(-) ornidazole and R-(+) ornidazole was further explored by evaluating the contents of glutamate (Glu) and γ-aminobutyric acid (GABA) in the brain, and Western blot was used to measure glutamic acid decarboxylase (GAD65/67) expression in the mice cerebral cortex. We found that R-(+) ornidazole mediated an increase in GABA level while decreased the level of glutamate through upregulation of GAD65/67 in the cerebral cortex. Taken together, our study suggests that R-(+) ornidazole mediate stronger central inhibitory effects than S-(-) ornidazole through interaction with the GABAergic system.

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.

Quantification of levornidazole and its metabolites in human plasma and urine by ultra-performance liquid chromatography-mass spectrometry.

We developed and validated an ultra-performance liquid chromatographic (UPLC) method coupled with atmospheric pressure chemical ionization (APCI) mass spectrometry for simultaneous determination of levornidazole and its first-pass metabolites, l-chloro-3-(2-hydroxymethyl-5-nitro-l-imidazolyl)-2-propanol (Ml), 2-methyl-5-nitroimidazole (M2) and 3-(2-methyl-5-nitro-1-imidazolyl)-1,2-propanediol (M4), in human plasma and urine. The biological samples were pretreated by protein precipitation and liquid-liquid extraction and analyzed using an ACQUITY UPLC CSH C18 column (2.1×50 mm, 1.7 µm) and a QTRAP mass spectrometer in multiple reaction monitoring mode via APCI. Acetonitrile and 0.1% formic acid in water was used as the mobile phase in gradient elution at a flow rate of 0.6 mL/min. The lower limit of quantification of this method was 0.0100, 0.00500, 0.0200 and 0.00250 µg/mL for levornidazole, M1, M2 and M4, respectively. The linear calibration curves were obtained for levornidazole, M1, M2, and M4 over the range of 0.0100-5.00, 0.00500-2.50, 0.0200-10.0 and 0.00250-1.25 µg/mL, respectively. The intra- and inter-batch precision was less than 12.2% in plasma and less than 10.8% in urine. The intra- and inter-batch accuracy was 87.8-105.7% in plasma and 92.8-109.2% in urine. The mean recovery of levornidazole, M1, M2 and M4 was 91.1-105.1%, 95.8-103.8%, 87.8-96.8%, 96.8-100.6% from plasma and 96.0-100.9%, 96.9-107.9%, 95.1-102.7%, 103.7-105.9% from urine respectively. This method was validated under various conditions, including room temperature, freeze-thaw cycles, long-term storage at -40 ± 5°C, after pretreatment in the autosampler (at 10°C), and 10- and 100-fold dilution. This newly established analytical method was successfully applied in a pharmacokinetic study following single intravenous infusion of levornidazole in 24 healthy Chinese subjects.

Enantioselective determination of ornidazole in human plasma by liquid chromatography-tandem mass spectrometry on a Chiral-AGP column.

A rapid, sensitive, and enantioselective method was developed and validated for determination of ornidazole enantiomers in human plasma by liquid chromatography-tandem mass spectrometry. Ornidazole enantiomers were extracted from 100µl of plasma using ethyl acetate. Baseline chiral separation (Rs=2.0) was obtained within 7.5min on a Chiral-AGP column (150mm×4.0mm, 5µm) using an isocratic mobile phase of 10mM ammonium acetate/acetic acid (100/0.01, v/v). Stable isotopically labeled R-(+)-d5-ornidazole and S-(-)-d5-ornidazole were synthesized as internal standards. Acquisition of mass spectrometric data was performed in multiple reaction monitoring mode via positive electrospray ionization, using the transitions of m/z 220→128 for ornidazole enantiomers, and m/z 225→128 for d5-ornidazole enantiomers. The method was linear in the concentration range of 0.030-10.0µg/ml for each enantiomer. The lower limit of quantification for each enantiomer was 0.030µg/ml. The relative standard deviation values of intra- and inter-day precision were 1.8-6.2% and 1.5-10.2% for R-(+)-ornidazole and S-(-)-ornidazole, respectively. The relative error values of accuracy ranged from -4.5% to 1.2% for R-(+)-ornidazole and from -5.4% to -0.8% for S-(-)-ornidazole. The validated method was successfully applied to a stereoselective pharmacokinetic study of ornidazole after oral administration of 1000mg racemic ornidazole.

[Correlation of ornidazole concentration in saliva and serum of healthy volunteers].

OBJECTIVE: To investigate the distribution of ornidazole in the salivary and serum of healthy adults and explore the feasibility of monitoring serum drug concentration with salivary. METHODS: Six volunteers received a single dose of 0.6 g ornidazole via intravenous infusion. The concentrations of ornidazole in the saliva and serum were assayed by high-performance liquid chomatography, and the correlation of the drug concentrations in saliva to that in serum was analyzed. RESULTS: The concentration of ornidazole in the saliva was strongly associated with that in the serum (r = 0.825-0.969), and the ratio of saliva-to-serum concentration (S/P) of ornidazole was 0.99 ± 0.13. CONCLUSION: Detection of saliva ornidazole concentration is feasible for monitoring the therapeutic concentration of ornidazole.

An improved HPLC method for determination of nifuratel in human plasma and its application to pharmacokinetics studies.

A rapid, simple and sensitive high-performance liquid chromatography (HPLC) method was established for the quantification of nifuratel in human plasma and applied to a study of its pharmacokinetics. A test and a reference formulation were investigated and compared, and the study group consisted of 24 healthy male volunteers. The analytical technique was based on a single extraction of the drug from the plasma with chloroform, using ornidazole as internal standard (IS). The chromatographic system consisted of a 5-microm 4.6 mmX250 mm C18 analytical column and the mobile phase consisted of methanol and purified water (45:55, v/v). Nifuratel and ornidazole concentrations were detected by ultraviolet (UV) absorbance at a wavelength of 254 nm. The lower limit of detection and quantification was 0.5 ng ml(-1), and the calibration curves were linear over a concentration range of 0.5-160 ng ml(-1) nifuratel in the plasma. The results showed that the area under the plasma concentration-time curve (AUC), time to maximum observed plasma concentration (Tmax), maximum concentration reached in the concentration profile (Cmax), and elimination half-life (t1/2) between the test tablets and the reference tablets demonstrated no significant difference (P>0.05). The relative bioavailability amounted to 103.13% +/-8.73%.

Effect of ketoconazole on the pharmacokinetics of ornidazole--a possible role of p-glycoprotein and CYP3A.

The influence of ketoconazole, a modulator of P-glycoprotein (P-gp), on the exsorption of ornidazole from everted sacs of rat intestine (duodenum, jejunum and ileum) was investigated. The effect of ketoconazole pretreatment on the pharmacokinetics of ornidazole was also studied in eight healthy human volunteers. After overnight fasting ornidazole 500 mg was administered before and after pretreatment with ketoconazole 200 mg once daily for 7 days. Serum samples were analyzed by reversed phase HPLC. Significant differences were observed in pharmacokinetic parameters C(max), AUC(0-t), AUC(0-infinity), T(max) and clearance. Ornidazole is believed to be metabolized through CYP3A and it has considerable intestinal efflux, which was observed from the in vitro study. The altered pharmacokinetic parameters can be attributed to ornidazole efflux from the blood to the intestine and its metabolism by CYP3A in the intestine.

Stereoselective pharmacokinetics of ornidazole after intravenous administration of individual enantiomers and the racemate.

The pharmacokinetics of ornidazole (ONZ) were investigated following i.v. administration of racemic mixture and individual enantiomers in beagle dogs. Plasma concentrations of ONZ enantiomers were analyzed by chiral high-performance liquid chromatography (HPLC) on a Chiralcel OB-H column with quantification by UV at 310 nm. Notably, the mean plasma levels of (-)-ONZ were higher in the elimination phase than those of (+)-ONZ. (-)-ONZ also exhibited greater t1/2, MRT, AUC(0-t) and smaller CL, than those of its antipode. The area under the plasma concentration-time curve (AUC(0-t)) of (-)-ONZ was about 1.2 times as high as that of (+)-ONZ. (+)-ONZ total body clearance (CL) was 1.4 times than its optical antipode. When given separately, there were significant differences in the values of AUC(0-infinity) and CL between ONZ enantiomers (P < 0.05), indicating that elimination of (+)-ONZ was more rapid than that of (-)-ONZ. No significant differences were found between the estimates of the pharmacokinetic parameters of (+)-ONZ or (-)-ONZ, obtained following administration as the individual and as a racemic mixture. This study demonstrates that the elimination of ONZ enantiomers is stereoselective and chiral inversion and enantiomer/enantiomer interaction do not occur when the enantiomers are given separately and as racemic mixture.

In vivo and real time determination of ornidazole and tinidazole and pharmacokinetic study by capillary electrophoresis with microdialysis.

The aim of this study was to develop a rapid and sensitive method for in vivo and real time monitoring unbound ornidazole (ONZ) and tinidazole (TNZ) in rabbit blood using capillary electrophoresis coupled with microdialysis. The UV wavelength was set at 214 nm and all separations were performed in 20 mM Tris-H3PO4 (pH 1.5) buffer. Microdialysis probes were perfused at 4 microl/min resulting in relative recoveries of 33.1+/-3.6% and 34.8+/-3.3% (n=3) for ONZ and TNZ, respectively. The linearity was studied in the concentration range of 1.0-412 microg/ml for ONZ and 1.0-520 microg/ml for TNZ. The detection limits were 0.7 microg/ml for ONZ and 0.6 microg/ml for TNZ (S/N=3). All separation could be achieved within 15 min. This method has been successfully applied to the pharmacokinetic study of ONZ and TNZ in rabbit blood.

In vivo evaluation of guar gum-based colon-targeted drug delivery systems of ornidazole in healthy human volunteers.

The aim of the present study was to find the in vivo performance of guar gum-based colon-targeted tablets of ornidazole (dose 250 mg) in comparison with an immediate release tablet of ornidazole (250 mg) in human volunteers. Six healthy volunteers participated in the study, and a cross over design was followed. The plasma concentration of ornidazole was estimated by HPLC. The immediate release tablets of ornidazole produced peak plasma concentration (Cmax of 2171.33+/-278.15 ng/ml) at 2.91+/-0.14 h (Tmax) whereas colon-targeted tablets produced peak plasma concentration (Cmax of 1716.66+/-125.83 ng/ml) at 11.91+/-0.14 h. The delayed Tmax, decreased Cmax, and decreased ka of ornidazole from guar gum-based colon-targeted ornidazole tablets, in comparison with the immediate tablets, indicated that the drug was not released in stomach and small intestine, but targeted to colon. Slow absorption of ornidazole from the less absorptive colon might result in the availability of drug for local action in the colon.

Disposition of ornidazole and its metabolites during pregnancy.

The disposition of ornidazole and its two major hydroxylated metabolites was studied in five pregnant women (gestational ages 25 5/7 to 38 4/7 weeks) with either chorioamnionitis or pyelonephritis treated with ceftriaxone 2 g, tobramycin 3 mg/kg body weight and ornidazole 1 g all administered once-daily. Two series of blood samples were obtained, the first on the first day of treatment and the second at steady-state on day 5. Local and systemic tolerability of ornidazole was excellent and patients showed complete remission without premature delivery. There was no evidence of ornidazole accumulation, and the pharmacokinetic parameters were very similar to those seen in healthy subjects. The dosage regimen of ornidazole therefore requires no adjustment during pregnancy. Trough concentrations of ornidazole measured at 24 h post dose were above the MIC of sensitive organisms. Children born to the trial patients showed normal initial development and their growth was normal.

Concentrations in plasma and tissue penetration of ceftriaxone and ornidazole during liver transplantation.

Plasma and epiploic fat drug concentrations and fat penetration of ceftriaxone and ornidazole given for antimicrobial prophylaxis were studied in 11 patients scheduled for liver transplantation. Ceftriaxone (1 g) and ornidazole (500 mg) were infused during 30 min after the induction of anesthesia. Arterial blood and epiploic fat samples were collected at 30, 60, and 120 min and then every 90 min following the end of the infusion until closure of the peritoneum. Blood samples were immediately centrifuged, and plasma and fat were stored at -35 degrees C until analysis. Ceftriaxone and ornidazole concentrations were determined by high-performance liquid chromatography. Surgery lasted 440 +/- 84 min and required a mean of 9.5 units of packed erythrocytes and 13 units of fresh frozen plasma. Plasma ceftriaxone concentrations decreased from 89 +/- 34 to 41 +/- 16.5 micrograms/ml from the beginning of the operation until the time of closure of the peritoneum. Corresponding levels in epiploic fat decreased from 8.7 +/- 3.3 to 4.5 +/- 3.5 micrograms/g. Ornidazole concentrations ranged, respectively, between 8.7 +/- 2.5 and 4.9 +/- 1.7 micrograms/ml in plasma samples and 4.6 +/- 1.2 and 2.5 +/- 1.1. micrograms/g in fat samples. Rates of penetration into the omentum remained at about 9% for ceftriaxone and between 50 and 70% for ornidazole. Tissue ceftriaxone concentrations were, in all cases, greater than typical MICs for 90% for Escherichia coli and Klebsiella isolates tested (MIC90S). They were insufficient in 40% of patients after 60 min with regard to the MIC90S for Staphylococcus aureus. Tissue ornidazole concentrations were not superior to MIC90S for anaerobes after 30 min in 50% of patients. These results show that a single dose of 1 g of ceftriaxone provides adequate coverage against gram-negative bacteria and that 1 g instead of 500 mg ornidazole may provide a protective effect against anaerobes during liver transplantation. Prophylaxis against S. aureus and Streptococcus faecalis requires more specific antibiotics. Prophylaxis for patients with significant blood loss or initial severe renal or hepatic failure needs further evaluation.

Pharmacokinetics and tissue penetration of a single dose of ornidazole (1,000 milligrams intravenously) for antibiotic prophylaxis in colorectal surgery.

Levels in serum and tissue penetration of ornidazole were studied after a single intravenous injection of 1,000 mg given to 14 patients for prophylaxis of surgical infection. They were scheduled for elective colorectal surgery. Adequate levels in blood (greater than or equal to MIC for 90% of Bacteroides fragilis strains tested) were found in all patients throughout the procedure and up to hour 24. Mean-maximal (15 min) and last-determined (24 h) ornidazole levels in serum were 24 +/- 5.2 and 6.3 +/- 1.4 mg/liter, respectively. beta-Phase elimination half-life was 14.1 +/- 2.7 h, and clearance and apparent volume of distribution were 47 +/- 12 ml/min and 0.9 +/- 0.13 liters/kg, respectively. In all patient, adequate levels in tissue were found in the abdominal wall and the epiploic fat at time of incision and in the colonic wall at time of anastomosis. At time of closure, all but one patient had adequate levels in tissue in the abdominal wall and the epiploic fat. No anaerobic nor aerobic infection occurred in the study patients.

[Study of gastric elimination of ornidazole after intravenous administration in patients undergoing digestive surgery]. / Etude de l'élimination gastrique de l'ornidazole après administration intraveineuse chez des patients en chirurgie digestive.

In a previous study, performed in patients undergoing gastrointestinal surgery receiving antibiotics intravenously we pointed out that the gastric aspiration was an additional route of elimination for some drugs. In order to estimate the extra-dose required to replace losses in patients receiving ornidazole, a study was set up. 8 patients entered the trial; the patients were infused 500 mg of ornidazole for 3 days every 12 hours. Blood was sampled at 0-2-4-8-24 h after the last infusion. Urines and gastric aspirate were collected. The results indicate that the amount aspirated through the tubings is 69.1 +/- 37.5 mg per 24 hours (24.8 - 116.8) with a very high variability; the half-life was not different of what is known for ornidazole: 10.5 +/- 1.7 h. The results confirm that for the molecules weakly bound to protein which "concentrate" in the gastric secretion, the aspiration is an important route of elimination.

Pharmacokinetics of ornidazole in patients with acute viral hepatitis, alcoholic cirrhosis, and extrahepatic cholestasis.

Pharmacokinetics of ornidazole, a nitroimidazole derivative, was investigated after intravenous injection in 3 groups of 10 patients with different hepatic diseases: hepatitis, noncholestatic cirrhosis and extrahepatic cholestasis. Plasma concentrations of ornidazole and its two major hydroxylated metabolites, M1 [alpha-(chloromethyl)-2-hydroxymethyl-5-nitroimidazole-1-ethanol] and M4 [3-(2-methyl-5-nitroimidazole 1-yl)-1,2-propane diol] were measured by HPLC assay. As a consequence of a decreased clearance (26% to 48%), the half-life and MRT are increased in all patients by 19% to 38% when compared with healthy volunteers. No clear difference could be established between the different groups. The volume of distribution remains the same in all patients and controls except those suffering from cancer. As previously shown in patients with severe liver cirrhosis, both metabolites accumulate in plasma as a result of decreased elimination; formation is no longer the rate-limiting step of their kinetics. This metabolite accumulation is in part due to decreased biliary excretion and to hepatocellular failure.

[Plasma concentrations of ornidazole in newborn infants and infants after iterative administration]. / Concentrations plasmatiques d'ornidazole chez le nouveau-né et chez le nourrisson après administration répétée.

Ornidazole was administered for ten days to twelve hospitalized neonates at the same daily dose of 20 mg/kg either by one or two IV infusions. Minimum steady-state concentrations measured between the 4th and 10th day ranged from 7.8 to 17.3 (mean = 11.8 +/- 3.2 mg/l) for one daily infusion and from 10.9 to 26.6 (mean = 20.5 +/- 6 mg/l) for two infusions. These minimum concentrations were all above the minimum inhibitory concentration for the most clinically significant anaerobic bacteria. So the single daily administration of ornidazole at the dose of 20 mg/kg is sufficient to obtain therapeutic efficiency.