Metronidazole

Metronidazole is a nitroimidazole antibiotic medication used particularly for anaerobic bacteria and protozoa. Target: Antibacterial; Antiparasitic Metronidazole is a nitroimidazole antibiotic medication used particularly for anaerobic bacteria and protozoa. Metronidazole is an antibiotic, amebicide, and antiprotozoal.[1] It is the drug of choice for first episodes of mild-to-moderate Clostridium difficile infection [2]. Metronidazole, taken up by diffusion, is selectively absorbed by anaerobic bacteria and sensitive protozoa. Once taken up by anaerobes, it is non-enzymatically reduced by reacting with reduced ferredoxin, which is generated by pyruvate oxido-reductase. Many of the reduced nitroso intermediates will form sulfinamides and thioether linkages with cysteine-bearing enzymes, thereby deactivating these critical enzymes. As many as 150 separate enzymes are affected.In addition or alternatively, the metronidazole metabolites are taken up into bacterial DNA, and form unstable molecules. This function only occurs when metronidazole is partially reduced, and because this reduction usually happens only in anaerobic cells, it has relatively little effect upon human cells or aerobic bacteria.[3]

References:
[1]. In Schaechter, M.; Engleberg, N. C.; DiRita, V. J. et al. Schaechter's Mechanisms of Microbial Disease. Hagerstown, MD: Lippincott Williams & Wilkins. p. 28. [2]. http://www.drugs.com/monograph/metronidazole.html [3]. Cohen, S.H., et al., Clinical practice guidelines for Clostridium difficile infection in adults: 2010 update by the society for healthcare epidemiology of America (SHEA) and the infectious diseases society of America (IDSA). Infect Control Hosp Epidemiol, 2010. 31(5): p. 431-55.

Hyperpolarizing Concentrated Metronidazole 15NO2 Group Over Six Chemical Bonds with More Than 15% Polarization and 20 Minute Lifetime.[Pubmed:30964568]

Chemistry. 2019 Apr 9.

NMR hyperpolarization of uniformly 15N-labeled Metronidazole-15N3 is demonstrated using SABRE-SHEATH (Signal Amplification by Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei). In this antibiotic, a 15NO2 group is hyperpolarized via spin relays created by 15N spins in Metronidazole-15N3, and the polarization is transferred from parahydrogen-derived hydrides over six chemical bonds. This efficient spin-relayed mechanism of polarization transfer is supported by measurements of polarization dynamics and T1 relaxation in micro-Tesla magnetic fields. In less than a minute of parahydrogen bubbling at ~0.4 microT, a high level of nuclear spin polarization P15N of ~16% is achieved on all three 15N sites of Metronidazole-15N3 at up to ~41 mM concentration. This product of 15N polarization and concentration of 15N spins is ~6-fold better than any previous value for 15N SABRE-derived hyperpolarization. At 1.4 T, the hyperpolarized state of the 15NO2 group of this antibiotic persists for tens of minutes (T1~10 min), in part because its 15N spin has no detectable spin-spin couplings with protons of the molecule. A novel synthesis achieving robust uniform 15N enrichment of Metronidazole is reported with 15% yield over three steps. This synthetic approach should be suitable for preparation of other 15N-labeled nitroimidazole derivatives, potentially enabling a wide range of in vivo metabolic probes from hypoxia sensing to theranostic imaging.

The prevalence of antibiotic-resistant Clostridium species in Iran: a meta-analysis.[Pubmed:30961444]

Pathog Glob Health. 2019 Apr 9:1-9.

Clostridium species are ubiquitous and associated with various diseases in animals and humans. However, there is little knowledge about the prevalence of their resistance to antibiotics in Iran. Therefore, the aim of this study was to determine the prevalence of antibiotic-resistant Clostridium species in Iran through a meta-analysis of eligible studies published up until December 2018. Fourteen articles on the drug resistance of Clostridium species in Iran were included in the current study following a search in PubMed, Scopus and Google Scholar databases using relevant keywords and screening based on inclusion and exclusion criteria. Antibiotic resistance rates of C. difficile to ampicillin (42.8%), ciprofloxacin (69.5%), clindamycin (84.3%), erythromycin (61.5%), gentamicin (93.5%), nalidixic acid (92.9%), tetracycline (32.5%), imipenem (39.6%), levofloxacin (93.4%), ertapenem (58.7%), piperacillin/tazobactam (56.5%), kanamycin (100%), colistin (100%), ceftazidime (76%), amikacin (76.5%), moxifloxacin (67.9%) and cefotaxime (95%) were high. In addition, resistance of C. perfringens to ampicillin (25.8%), erythromycin (32.9%), gentamicin (45.4%), nalidixic acid (52.5%), tetracycline (19.5%), penicillin (21.8%), trimethoprim-sulfamethoxazole (32.1%), amoxicillin (19.3%), imipenem (38%), cloxacillin (100%), oxacillin (45.6%), bacitracin (89.1%) and colistin (40%) was high. Metronidazole and vancomycin, as the first-line therapies, fidaxomicin, tetracyclines (except tetracycline), rifampicin and chloramphenicol can still be used for the treatment of C. difficile infections. However, the present results do not recommend the use of penicillin, bacitracin and tetracycline for the treatment of C. perfringens infections in humans and domestic animals in Iran.

Preparation and Evaluation of Metronidazole-Loaded Pectin Films for Potentially Targeting a Microbial Infection Associated with Periodontal Disease.[Pubmed:30960947]

Polymers (Basel). 2018 Sep 13;10(9). pii: polym10091021.

The objective of this study was to develop the Metronidazole loaded high and low methoxyl pectin films (HM-G-MZ and LM-G-MZ) for the treatment of periodontal disease. The films were prepared by pectin 3% w/v, glycerin 40% w/v, and Metronidazole 5% w/v. The developed films were characterized by scanning electron microscope and evaluated for thickness, weight variation, and elasticity. The developed films showing optimal mechanical properties were selected to evaluate radial swelling properties, in vitro release of Metronidazole and the antimicrobial activity against Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans by the disc diffusion method. The results demonstrated that LM-MZ and HM-G-MZ films were colorless and yellowish color, respectively, with the film thickness around 0.36(-)0.38 mm. Furthermore, both films exhibited good elasticity with low puncture strength (1.63 +/- 0.37 and 0.84 +/- 0.03 N/mm(2), respectively) and also showed slight increase in radial swelling, so that they could be easily inserted and fitted into the periodontal pocket during a clinical use. However, HM-G-MZ showed a decrease in radial swelling after 1 h due to the film erosion. The in vitro release study of LM-G-MZ showed a burst release that was initially followed by a slow release rate profile, capable to maintain the therapeutic level in periodontal pocket for seven days, whereas HM-G-MZ showed an immediate release profile. The cumulative percentage of Metronidazole release from HM-G-MZ was less than LM-G-MZ during the first 5 min as Metronidazole was in a crystalline form inside HM-G-MZ film. For antimicrobial activity test, both films showed the inhibitory effect against P. gingivalis and A. actinomycetemcomitans, and there was no difference in the inhibition zone between LM-G-MZ and HM-G-MZ. The present study showed, for the first time, that low methoxyl pectin film containing glycerin and Metronidazole could be potentially considered as a promising clinical tool for the drug delivery via intra-periodontal pocket to target an oral disease that is associated with polymicrobial infection.

A New Controlled-Release Material Containing Metronidazole and Doxycycline for the Treatment of Periodontal and Peri-Implant Diseases: Formulation and In Vitro Testing.[Pubmed:30956660]

Int J Dent. 2019 Mar 5;2019:9374607.

Background: Several locally administered antimicrobials have been studied in the literature as adjunctive or primary treatments for periodontitis and peri-implantitis with conflicting results. Objective: The aim of this study was twofold: (1) the formulation of a controlled-release material containing Metronidazole and doxycycline; (2) an in vitro evaluation of its antibacterial properties against planktonic and biofilm species involved in periodontal and peri-implant diseases. Methods: Doxycycline (10 mg/ml) and Metronidazole (20 mg/ml) were incorporated into a hydroxyethylcellulose-polyvinylpyrrolidone-calcium polycarbophil gel. Three milliliters of gel were dialyzed against Dulbecco's phosphate-buffered saline for 13 days. Antibiotics release at 3, 7, 10, and 13 days was determined spectroscopically. The inhibitory activity of the experimental gel was tested against A. actinomycetemcomitans, S. sanguinis, P. micra, and E. corrodens with an agar diffusion test, an inactivation biofilm test, and a confocal laser scanning microscope study (CLSMS) for S. sanguinis up to 20 days. Results: After 13 days, the released doxycycline was 9.7% (at 3 days = 1.2 mg; 7 days = 0.67 mg; 10 days = 0.76 mg; 13 days = 0.29 mg), while Metronidazole was 67% (30 mg, 6.8 mg, 2.5 mg, and 0.9 mg at the same intervals). The agar diffusion test highlights that the formulated gel was active against tested microorganisms up to 312 h. Quantitative analysis of biofilm formation for all strains and CLSMS for S. sanguinis showed a high growth reduction up to 13 days. Conclusions: The in vitro efficacy of the newly formulated gel was confirmed both on planktonic species and on bacterial biofilm over a period of 13 days. The controlled-release gel containing Metronidazole and doxycycline had an optimal final viscosity and mucoadhesive properties. It can be argued that its employment could be useful for the treatment of periodontal and peri-implant diseases, where conventional therapy seems not successful.

Infection-responsive electrospun nanofiber mat for antibacterial guided tissue regeneration membrane.[Pubmed:30948089]

Mater Sci Eng C Mater Biol Appl. 2019 Jul;100:523-534.

The release of anti-infection drugs in a targeted and efficient manner in response to the attack time and degree of severity of infection is a requirement of new generation implants. Herein, we design an infection-responsive guided tissue regeneration (GTR)/guided bone regeneration (GBR) membrane based on electrospun nanofibers. Polycaprolactone (PCL) nanofiber mats are coated with polydopamine to endow hydroxyl groups on the surface and then functionalized with siloxane to introduce amino groups. Metronidazole (MNA), an antibiotic drug, is esterified and then grafted onto the surface of the modified PCL nanofiber mats via ester linkages. The ester bonds can be selectively hydrolyzed by cholesterol esterase (CE), an enzyme secreted by macrophagocytes accumulated at the site of infection, whose concentration is positively related to the severity of the infection. The drug can be triggered to release from the nanofiber membranes in responsive to the CE. With the increase of the CE concentration, a higher amount of MNA is released from the nanofiber mat, resulting in the enhancement of the antibacterial capability of the MNA-grafted nanofiber mat. The nanofiber mat has good cytocompatibility. This CE-responsive drug delivery system based on the electrospun nanofiber mat is promising as an optimal choice for antibacterial GTR/GBR membrane.