Chromatographic analysis of ciprofloxacin and metronidazole in real human plasma: green analytical chemistry perspective.

Background: Ciprofloxacin and metronidazole are beneficial for treating mixed aerobic/anaerobic infections. Methods: Following the oral administration of ciprofloxacin and metronidazole in healthy volunteers, TLC and HPLC methods were described for their analysis in plasma samples. In the first method, a stationary phase of silica gel TLC F254 plates was used using acetone/water/triethylamine/glacial acetic acid (8:2:0.25:0.1 v/v). The second approach used a C18 column and methanol/aqueous 0.05% triethylamine (25:75 v/v), with a flow rate of 1 ml/min and detection at 325 nm. Four green metrics were used to evaluate the approaches' environmental impact. Conclusion: The study provided the sensitivity required for determination of the two drugs in the collected samples. The findings showed that results were within permitted ranges with minimal environmental impact.

Effects of metronidazole on mesophilic and thermophilic fermentation: Biodegradation mechanisms, microbial communities, and reversibility.

Metronidazole (MNZ), an antibiotic that is specifically used for the treatment of anaerobic infections, may inhibit anaerobic fermentation. This work was designed to understand the fate and effects of MNZ in mesophilic fermentation (MF) and thermophilic fermentation (TF), respectively. The results showed that the removal of MNZ mainly occurred via biodegradation, rather than adsorption, and that MNZ could be completely degraded by opening the imidazole ring. MFs were more strongly inhibited by MNZ than TFs. MNZ concentration increased from 0 to 25 mg/L, hydrogen yield (HY) decreased from 167.5 to 16.8 mL/g glucose (90.0% decrease), and butyrate yield almost completely disappeared in MFs, whereas in TFs, HY decreased only from 101.1 to 89.3 mL/g glucose (11.7% decrease), and ethanol yield increased by 39.8%. Illumina MiSeq sequencing analysis showed that MNZ reduced the abundance of hydrogen-producing bacteria. Furthermore, the inhibition of MNZ on anaerobic fermentation was reversible.

Crystal morphology control of synthetic giniite for enhanced photo-Fenton activity against the emerging pollutant metronidazole.

Metronidazole (MNZ) is a recalcitrant antibiotic with toxic and carcinogenic effects in aquatic environments. In this work, Fe5(PO4)4(OH)3·2H2O (giniite) particles were synthesised with three different alkaline cations (Li+, Na+ and K+) and used as Fenton catalysts for MNZ removal. It is shown that the addition of different cations during the hydrothermal synthesis process promote different morphologies from asterisk-like to flower-like and branches-like, maintaining the crystalline structure of pure giniite. The photo-Fenton activity of these particles was then evaluated through the degradation of MNZ under sunlight radiation for 9 h. The results indicate that the alkaline cation has a predominant role in the photo-Fenton efficiency, as demonstrated by the superior degradation efficiencies of Na@giniite particles (91.2% and 72.5% with giniite concentration of 0.2 g L-1 and 0.07 g L-1, respectively), related with its high surface area (10.7 m2 g-1). Thus, it is demonstrated the suitability of Na@giniite particles as Fenton catalyst for MNZ removal from water.

Electrochemical determination of chloramphenicol and metronidazole by using a glassy carbon electrode modified with iron, nitrogen co-doped nanoporous carbon derived from a metal-organic framework (type Fe/ZIF-8).

In this study, an iron-doped metal-organic framework (MOF) Fe/ZIF-8 was synthesized from ZIF-8 at room temperature. Direct carbonization of Fe/ZIF-8 under a nitrogen atmosphere produced nanoporous nitrogen doped carbon nanoparticles decorated with Fe component (Fe/NC). The Fe/NC exhibited a large surface area (1221.185 m2 g-1) and narrow pore-size distribution (3-5 nm). The nanoporous Fe/NC components along with Nafion were used to modify a glassy carbon electrode for the electrochemical determination of chloramphenicol and metronidazole via linear sweep voltammetry. Under optimal conditions, the reduction peak currents (observed at -0.237 V and -0.071 V vs. Ag/AgCl) of these analytes increased linearly with increasing chloramphenicol and metronidazole concentrations in the range of 0.1-100 µM and 0.5-30 µM, with the detection limits estimated to be 31 nM and 165 nM, respectively. This result was attributed to the large surface area, porous structure, high nitrogen content, and as well as the electrocatalytic effect of Fe atoms embeded in the carbon support. The proposed sensor was used for chloramphenicol and metronidazole analysis in samples, providing satisfactory results.

Efficient preparation of nitrogen-doped fluorescent carbon dots for highly sensitive detection of metronidazole and live cell imaging.

Herein, nitrogen-doped carbon dots (N-CDs) emitting blue fluorescence were prepared using L-tartaric acid and triethylenetetramine through a simple and quick microwave-assisted method. The synthesized N-CDs displayed excitation-dependent fluorescence behavior, and their maximum excitation and emission wavelengths were 350 and 425 nm, respectively. The obtained N-CDs, which featured excellent fluorescence properties with a high fluorescence quantum yield of 31%, were applied to detect metronidazole (MNZ), which can effectively quench the fluorescence intensity of N-CDs due to the inner filter effect. This phenomenon was used as basis to develop a label-free fluorescent method for rapid MNZ determination, with the limit of detection of 0.22 µM and corresponding linear range of 0.5-22 µM. Hence, we had established a fluorescence method for MNZ detection and applied it to detect MNZ in real samples with satisfactory results. Finally, N-CDs with superior biocompatibility were applied for cell imaging and MNZ detection by the changes in fluorescence intensity.

In-situ insertion of multi-walled carbon nanotubes in the Fe3O4/N/C composite derived from iron-based metal-organic frameworks as a catalyst for effective sensing acetaminophen and metronidazole.

In this paper, a novel Fe3O4/N/C@MWCNTs composite derived from iron-based metal-organic frameworks (H2N-Fe-MIL-88B) with multi-walled carbon nanotubes (MWCNTs) was prepared successfully through a simple calcination process. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and electrochemical measurements were employed to comprehensive characterize the composites. Compare with the physical mixture, in-situ insertion of MWCNTs in the Fe3O4/N/C formed Fe3O4/N/C@MWCNTs composite has the higher conductivity, larger BET surface area and more satisfying electrocatalytic properties. Meanwhile, this composite with the reasonable combinations exhibits remarkable electrocatalytic activities for acetaminophen (AP) and metronidazole (MNZ) due to the synergistic interaction between the components. Thus, the Fe3O4/N/C@MWCNTs-2-600-based electrochemical sensor was established to effectively detect these two medicine molecules, respectively. In the optimized test conditions, the proposed sensor exhibits a wide linear response (0.5-5.0 µM and 5.0-1355.0 µM) for AP and the limit of detection (LOD) was achieved to be 0.14 µM (S/N = 3). Meanwhile, this sensor also shows two linear relationships with the concentration of MNZ in the range of 1.0 µM to 10.0 µM and 10.0 µM to 725.0 µM with the LOD of 0.19 µM (S/N = 3). Moreover, the satisfactory results were also acquired when the proposed sensor was used for the determination of AP and MNZ in the human serum and urine, demonstrating great promising of this electrochemical sensor for clinical applications.

Electrochemical treatment of pharmaceutical wastewater through electrosynthesis of iron hydroxides for practical removal of metronidazole.

Antibiotics as the severe contaminants of aqueous environments were received growing attention during the last decades. The current work is the first report on investigating the potency and efficiency of electrocoagulation process in the successful removal of metronidazole (MNZ) from pharmaceutical wastewater using response surface methodology based on central composite design. The applied method by optimizing the independent and combined effects of significant variables which affecting the EC process enhanced the removal efficiency of MNZ. Analysis of variance was applied to verify the significance of independent variables solely and their interactions. The best removal efficiency of 100% found under the optimal operating condition of initial MNZ concentration 21.6 mg L-1, pH 8.2, current density 6.0 mA cm-2, inter-electrode distance 3 cm, and reaction time of 14.6 min. Isotherm investigations revealed that the Langmuir model with the R2 of 0.994 best fitted to the obtained experimental equilibrium results. The fast adsorption of MNZ on the surface of Fe(OH)3 and [Fe(OH)2]+ with the equilibrium time of 15 min confirmed that the kinetics of the electrocoagulation process follow the pseudo-second-order model (R2 = 0.962). The electrocoagulation process under the optimal operating condition revealed that the electrical energy consumption per each m3 of treated pharmaceutical wastewater, per each g of MNZ, removed, and per each kg of Fe electrode consumed, were found to be 0.516 kWh m-3, 0.0234 kWh g-1, and 0.0436 kWh kg-1, respectively.

A QuEChERS-Based Sample Preparation Method for the Analysis of 5-Nitroimidazoles in Bovine Milk by HPLC-DAD.

In this study, a simple, cost-effective, and sensitive HPLC diode-array detection method was developed for the simultaneous determination of six different 5-nitroimidazoles [metronidazole, 2-hydroxymethyl-1-methyl-5-nitro-1H-imidazole, dimetridazole (DMZ), ronidazole, ornidazole, and ipronidazole] in bovine milk samples. A QuEChERS-based sample preparation procedure was optimized by evaluating different cleanup sorbents, including zirconium-based sorbents (Z-Sep and Z-Sep+), C18, and primary-secondary amine (PSA), as well as EMR-Lipid cleanup solution. Acceptable analytical performance for all analytes was observed with recoveries in the range of 45-93% and RSDs of less than 15%. Negligible matrix interference was observed for most of the analytes due to application of PSA sorbent in a dispersive solid-phase extraction cleanup step. Method LOQs (mLOQs) for five of the six investigated analytes were set at a satisfactory low food product value of 2.5 ng/mL. For DMZ only, the mLOQ was set at 10 ng/mL. The procedure was evaluated through the analysis of 10 different natural samples.

Metronidazole thermogel improves retention and decreases permeation through the skin

ABSTRACT Metronidazole (MTZ) is widely used as the standard antibiotic for the treatment of rosacea and, more recently, is being used off label in Brazilian hospitals for the treatment of wounds. Following oral administration, minimal amounts of active agent reaches the skin and side effects are strongly induced. Consequently, MTZ is currently being applied topically in order to improve the therapeutic efficacy with reduced side effects, with Rozex(r) (RZ) (an MTZ gelled formulation) being the only marketed product. This study examined whether the use of MTZ 0.75% from thermogel formulations could improve drug retention and reduce dermal exposure compared to that by Rozex(r). Following a 21 h permeation study, the highest total amount of MTZ permeated through the rat healthy and disturbed skin was seen with Rozex(r), but similar to all formulations regardless of the skin condition. On the other hand, the amount retained in the epidermis/dermis was larger for thermogel formulations; at least 4 fold that of Rozex(r), when the stratum corneum was present as a barrier. In conclusion, thermogel formulations can be favorable alternatives to Rozex(r) for the topical application of MTZ with improved efficacy and reduced side effects.

Efecto del metronidazol suplementado con hidroquinona en la adherencia de Lactobacillus acidophilus en células vaginales ovinas / Effect of metronidazole supplemented with hydroquinone on the adhesion of Lactobacillus acidophilus in ovine vaginal cells

This work demonstrates that the addition of metronidazole together with a ubiquitous quinone compound reduces adherence of Lactobacillus acidophilus to ovine vaginal cells. Spectrophotometric and voltammetric studies have shown that neoformed compounds were observed in these systems; there were also changes in their electroactive composition, and the oxidant status had a significantly higher value compared to the control (p < 0.05). Based on reduction potential (E; mV), the distribution of electroactive compound concentrations suggests that the compounds with low reduction potential induce this behavior, which would indicate that the addition of metronidazole with a ubiquitous quinone compound to the vaginal system might increase the reductive capacity of these systems. This work shows that the study of behavior and fluctuations of the redox compounds that compose the vaginal environment, in terms of concentration and species of redox molecules, must be hierarchized in order to better understand the early stages of colonization by microorganisms.

Este trabajo demuestra que la incorporación de metronidazol conjuntamente con un compuesto quinónico ubicuo disminuye la adherencia de Lactobacillus acidophilus a células vaginales ovinas. Los estudios espectrofotométricos y voltamétricos mostraron que en estos sistemas aparecieron compuestos neoformados y que hubo modificaciones en la composición electroactiva; asimismo, el estatus oxidante presentó un valor significativamente superior con respecto al control (p < 0,05). Según los potenciales de reducción (E; mV), la distribución de las concentraciones de los compuestos electroactivos muestra que los compuestos con bajos potenciales de reducción inducen este comportamiento. Esto indicaría que la incorporación de esta mezcla al sistema vaginal aumentaría su capacidad reductora. El trabajo muestra que el estudio del comportamiento y las fluctuaciones de los compuestos redox que componen el ambiente vaginal, en términos de concentración y especies moleculares, debe ser jerarquizado para comprender mejor las primeras etapas de la colonización de este ambiente por parte de los microorganismos.

Gold nanoparticle-enhanced target for MS analysis and imaging of harmful compounds in plant, animal tissue and on fingerprint.

Gold nanoparticle-enhanced target (AuNPET) was used for detailed investigation of various materials of biological origin - human fingerprint, onion bulb and chicken liver. Analysis of these objects was focused on toxic and harmful compounds - designer drug containing pentedrone, diphenylamine in onion and potentially cancerogenic metronidazole antibiotic in liver. Detection of large quantity of endogenous compounds from mentioned objects is also shown. Most of analyzed compounds were also localized with MS imaging and relationship between their function and location was discussed. Detected compounds belong to a very wide range of chemical compounds such as saccharides, ionic and non-ionic glycerides, amino acids, fatty acids, sulfides, sulfoxides, phenols etc. Fingerprint experiments demonstrate application of AuNPET for detection, structure confirmation and also co-localization of drug with ridge patterns proving person-drug contact.

Novel electrochemical sensing platform based on a molecularly imprinted polymer decorated 3D nanoporous nickel skeleton for ultrasensitive and selective determination of metronidazole.

A novel electrochemical sensor has been developed by using a composite element of three-dimensional (3D) nanoporous nickel (NPNi) and molecularly imprinted polymer (MIP). NPNi is introduced in order to enhance the electron-transport ability and surface area of the sensor, while the electrosynthesized MIP layer affords simultaneous identification and quantification of the target molecule by employing Fe(CN)6(3-/4-) as the probe to indicate the current intensity. The morphology of the hybrid film was observed by scanning electron microscopy, and the properties of the sensor were examined by cyclic voltammetry and electrochemical impedance spectroscopy. By using metronidazole (MNZ) as a model analyte, the sensor based on the MIP/NPNi hybrid exhibits great features such as a remarkably low detection limit of 2 × 10(-14) M (S/N = 3), superb selectivity in discriminating MNZ from its structural analogues, and good antiinterference ability toward several coexisting substances. Moreover, the proposed method also demonstrates excellent repeatability and stability, with relative standard deviations of less than 1.12% and 1.4%, respectively. Analysis of MNZ in pharmaceutical dosage form and fish tissue is successfully carried out without assistance of complicated pretreatment. The MIP/NPNi composite presented here with admirable merits makes it a promising candidate for developing electrochemical sensor devices and plays a role in widespread fields.

Development and validation of HPLC-DAD method for the simultaneous determination of amoxicillin, metronidazole and rabeprazole sodium. Application to spiked simulated intestinal fluid samples.

This work deals with the development, validation and application of an HPLC-DAD method for the determination of a ternary mixture containing amoxicillin (AX), metronidazole (MZ) and the proton pump inhibitor rabeprazole sodium (RB). This triple therapy is used for treatment of Helicobacter pylori infection. Effective chromatographic separation between the three drugs was achieved using Thermo Hypersil BDS-C8 (4.6×250mm, 5µm particle size) column and a mobile phase composed of phosphate buffer pH 7 and acetonitrile (70: 30, by volume). The mobile phase was pumped isocratically at a flow rate of 1 mL/min. Quantification of the analytes was based on measuring their peak areas at 230nm for both AX and RB, and at 319nm for MZ. AX, MZ and RB eluted at retention times 2.36, 3.55 and 8.72min respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to linearity, ranges, precision, accuracy, selectivity, robustness, detection and quantification limits. The linear dynamic ranges were 25-250, 25-250 and 5-50µg/mL for AX, MZ and RB respectively with correlation coefficients>0.9998. The validated method was successfully applied to the analysis of several laboratory-prepared mixtures as well as simulated intestinal fluid samples spiked with the three drugs.

Depletion of metronidazole in brook trout (Salvelinus fontinalis).

Metronidazole (MNZ), which is effective in the treatment of intestinal infections in fish, is also a suspected carcinogen and has been banned in numerous jurisdictions for use in any food-producing animal, including fish. Few reports have been published on the depletion of MNZ in fish. A depletion study was therefore undertaken using MNZ in feed provided to trout under controlled conditions. The water was maintained at 17.5 ± 0.9°C throughout the medication and depletion periods in the study. Following a 20-day acclimatisation period in the holding tanks, the trout (approximately 150-200 g bodyweight at the start of the study) were subjected to two separate medication and withdrawal periods: (A) 5 day medication/5 day withdrawal and (B) 5 day medication/16 day withdrawal. This simulated a potential multiple dosing in an aquaculture setting. In both medication periods, the trout were dosed with medicated feed containing 3 g MNZ kg(-1) fish. Fish were sacrificed in accordance with accepted animal care protocols and tissue samples were analysed by UPLC-MS/MS. Analyte concentrations in trout muscle ranged from a high of 27,000 ± 10,000 ng g(-1) for MNZ and 830 ± 570 ng g(-1) for MNZ-OH on day 1 of withdrawal period A to a low of 1.8 ± 2.3 ng g(-1) for MNZ and < 0.4 ng g(-1) for MNZ-OH on day 16 of withdrawal period B. The results demonstrate that when using the UPLC-MS/MS method, residues of MNZ may be detected in fish treated with MNZ after 16 days of withdrawal.

Determination of metronidazole residues in water, sediment and fish tissue samples.

Metronidazole (MNZ) is an antibacterial and antiprotozoal drug used in veterinary and human medicine. Its continual entry into the environment and its biological properties may have significant, long-term effects on the stability of ecosystems because MNZ and its metabolites possess mutagenic, carcinogenic and toxic properties. For this reason, the application of MNZ in food-producing species is prohibited in the EU, the USA and other countries. To ensure human food safety and to protect the environment, robust and reliable screening and confirmatory tests capable of the low-level detection of MNZ residues are required. The development of methods for MNZ determination in biological and environmental samples is thus an important analytical task in environmental and food science. This work focuses on the evaluation of a method for determining MNZ in water, sediment and fish tissue samples using liquid chromatography--ion trap mass spectrometry (LC-MS/MS). MNZ was extracted from waters on Strata XC cartridges using solid phase extraction (SPE), and from sediments and fish tissues by solid-liquid extraction (sediment: 15 mL 0.1 M HCl (pH=0.6), 15 min; fish tissue: 15 mL 1% CH3COOH in ACN, 1 min; drying: 5 g MgSO4(anhyd.; 30 s) with SPE purification of the extracts (from sediment: Strata XC cartridge; from fish tissue: Supelco NH2 cartridge). The optimal procedure that we developed was validated in order to confirm its reliability and sensitivity. Matrix effects (ME) were established. Absolute recoveries ranged from 89.3% to 97.2%, and the method detection limits were 3.4 ng L(-1) (water samples), 0.4 ng g(-1) (sediment samples) and 0.3 ng g(-1) (tissue samples). These methods were used to determine MNZ in surface waters, sediments and fish tissues from the Polish River Goscicina; MNZ was found in all these matrices. The highest concentrations in water, sediment and tissue were 136.2 ng L(-1), 12.0 ng g(-1) and 1.5 ng g(-1) respectively. The results confirmed that these methods are suitable for the simultaneous analysis of waters, sediments and fish tissues for the presence of MNZ.

Electrochemical synthesis of nickel-iron layered double hydroxide: application as a novel modified electrode in electrocatalytic reduction of metronidazole.

A new and simple approach based on the electrochemical method was used for preparation of reproducible nanostructure thin film of Ni/Fe-layered double hydroxides (Ni/Fe-LDH) on the glassy carbon electrode (GCE). The electrochemical behavior of the Ni/Fe-LDH deposited on GCE electrode is studied. Study of the scanning electron microscopy shows the formation of a nanostructure thin film on the glassy carbon electrode. Electrochemical experiments show that Ni/Fe-LDH modified glassy carbon electrode exhibits excellent electrocatalytic reduction activity with Metronidazole. The method was successfully applied for the analysis of Metronidazole in tablets. The results were favorably compared to those obtained by the reported BP method.

[Experimental study on concentrations and pharmacokinetics of antibiotics in bile and evaluation of their microbicidal potential].

OBJECTIVE: To study the concentrations and pharmacokinetics of 6 different kinds of antibiotics in rabbit bile, and evaluate their microbicidal potential. METHODS: Thirty-six health rabbits were randomly divided into 6 groups, and each group was 6 rabbits. After anaesthesia, the common bile duct of rabbit was isolated and cumulated with a silicone tube. The rabbits were administered intravenously with the equal-effect dose of antibiotics. Bile (1.5 ml) was collected at different time points after administration, and the concentration of antibiotics of bile was assayed by high performance liquid chromatography. The bile drug concentration-time data were processed by software to figure out the pharmacokinetic parameters such as maximum concentration (C(max)), peak time (T(max)), half-life time (T(1/2)), clearance (CL) and apparent volume of distribution (VD). The bile antibiotics concentration contrasted to the minimum inhibitory concentration (MIC), and attained the bactericidal index (C(max)/MIC) and the time when the drug concentration exceeded the MIC (T(>MIC)). RESULTS: The C(max) and T1/2 of each antibiotic were as the followings: piperacillin (7 950 ± 3 023) mg/L and (1.97 ± 1.23) h, ceftriaxone (1 104 ± 248) mg/L and (3.14 ± 0.57) h, cefoperazone (5 215 ± 2 225) mg/L and (0.89 ± 0.13) h, meropenem (31.97 ± 12.44) mg/L and (0.36 ± 0.11) h, levofloxacin (66.3 ± 36.9) mg/L and (3.32 ± 2.57) h, metronidazole (28.2 ± 10.2) mg/L and (0.81 ± 0.33) h, respectively. Piperacillin/tazobactam and cefoperazone/sulbactam had the largest bactericidal index and the longest T(>MIC), and their bactericidal indexes were (62.1 ± 23.6) - (993.8 ± 377.9) and (164.8 ± 69.0) - (659.3 ± 275.9), their T(>MIC) were (6.00 ± 2.53) - (8.00 ± 0.00) h and (6.33 ± 1.97) - (8.00 ± 0.00) h. The bactericidal index and T(>MIC) of levofloxacin were the smallest, which were (2.1 ± 1.2) - (8.3 ± 4.6) and (0.54 ± 0.25) - (2.67 ± 1.03) h . Ceftriaxone and meropenem were as the medium, and their bactericidal indexes and T(>MIC) were (4.3 ± 1.0) - (69.2 ± 15.5) , (1.42 ± 0.65) - (8.00 ± 0.00) h and (2.0 ± 0.8) - (1 031.3 ± 401.4) , (0.29 ± 0.10) - (1.83 ± 0.26) h. The bactericidal index of metronidazole to anaerobic ranged from 7.4 to 294.9, and the T(>MIC) ranged from 1.88 to 5.00 h. CONCLUSIONS: The bile concentrations of six antibiotics all exceed their effective bactericidal concentrations. The concentration-time curves of piperacillin, cefoperazone, meropenem and metronidazole conformed to one-compartment model, and ceftriaxone and levofloxacin are conformed to two-compartment model. Piperacillin/tazobactam and cefoperazone/sulbactam have the largest bactericidal index and the longest T(>MIC), so they can be chosen as the first choice for the therapy of hepatobiliary infection.For the anaerobic, the microbicidal potential of metronidazole is high.

A novel composite film derived from cysteic acid and PDDA-functionalized graphene: enhanced sensing material for electrochemical determination of metronidazole.

A novel composite film derived from cysteic acid and poly(diallydimethylammonium chloride)-functionalized graphene (PDDA-GN) was employed as an enhanced electrode material for ultrasensitive determination of metronidazole. The cysteic acid/PDDA-GN composite film was prepared by the electrochemical grafting of cysteic acid onto the PDDA-GN coated glassy carbon electrode (GCE). The cyclic voltammetry investigations reveal that the peak current of metronidazole reduction at the cysteic acid/PDDA-GN/GCE was remarkably enhanced compared to the bare GCE, the cysteic acid/GCE and the PDDA-GN/GCE. This result implies the synergistic electrocatalytic effect of cysteic acid and PDDA-GN. The fabricated sensor shows linear response to metronidazole in the ranges of 10 nM-1 µM and 70 µM-800 µM, with a detection limit of 2.3 nM (S/N=3). The heterogeneous electron transfer rate constant and the diffusion coefficient of metronidazole were further evaluated by rotating disk electrode experiments. Moreover, we applied the present method to the determination of metronidazole in urine and lake water with satisfactory results.

Metronidazole-containing gel for the treatment of periodontitis: an in vivo evaluation

The aim of this investigation was to monitor metronidazole concentrations in the gingival crevicular fluid (GCF) collected from periodontal pockets of dogs after treatment with an experimental 15 percent metronidazole gel. Five dogs had periodontitis induced by cotton ligatures placed subgingivally and maintained for a 30-day period. After the induction period, only pockets with 4 mm or deeper received the gel. Each pocket was filled up to the gingival margin by means of a syringe with a blunt-end needle. GCF was collected in paper strips and quantified in an electronic device before and after 15 minutes, 1 h, 6 h, 24 h and 48 h of gel administration. The GCF samples were assayed for metronidazole content by means of a high performance liquid chromatography method. Concentrations of metronidazole in the GCF of the 5 dogs (mean ± SD, in µg/mL) were 0 ± 0 before gel application and 47,185.75 ± 24,874.35 after 15 minutes, 26,457.34 ± 25,516.91 after 1 h, 24.18 ± 23.11 after 6 h, 3.78 ± 3.45 after 24 h and 3.34 ± 5.54 after 48 h. A single administration of the 15 percent metronidazole gel released the drug in the GCF of dogs in levels several-fold higher than the minimum inhibitory concentration for some periodontopathogens grown in subgingival biofilms for up to one hour, but metronidazole could be detected in the GCF at least 48 hours after the gel application.

Validation of a method for the detection and confirmation of nitroimidazoles and the corresponding hydroxy metabolites in pig plasma by high performance liquid chromatography-tandem mass spectrometry.

Nitroimidazoles (Ronidazole, Dimetridazole, Metronidazole, Ipronidazole) and their hydroxy metabolites are banned substances with antibiotic and anticoccidial activity. They are suspected to be carcinogenic and mutagenic. Since nitroimidazoles showed an inhomogeneous distribution and a rapid degradation in incurred muscle samples, plasma is the preferred target matrix for residue analysis. The analytical method of Polzer et al. [J. Polzer, C. Stachel, P. Gowik, Anal. Chim. Acta 521 (2004) 189] was adapted for liquid chromatography-tandem mass spectrometry detection and was validated in house according to the Commission Decision 2002/657/EC. The method is specific for all nitroimidazole except for Ipronidazole and its metabolite, due to interferences at their retention times in chromatograms of blank plasma and reagents samples. The absence of a matrix effect enables the use of a (linear) calibration curve in solution for quantitation. The apparent recovery (obtained after correction with a deuterated internal standard) is between 93% and 123%, except for the metabolite of Metronidazole (58-63%). The repeatability (CVr=2.49-13.39%) and intralaboratory reproducibility (CVRW=2.49-16.38%) satisfy the Horwitz equation. The obtained values for the detection capacity (CCbeta) range from 0.25 to 1 microg L(-1), while values obtained for the decision limit (CCalpha) are below CCbeta.