Innovative Use of Topical Metronidazole

Metronidazole may display anti-inflammatory features in periodontitis treatment: A scoping review

AIM

Metronidazole (MTZ) is an antimicrobial agent used to treat anaerobic infections. It has been hypothesized that MTZ may also have anti-inflammatory properties, but the evidence is limited and has not been previously reviewed. Thus, this scoping review aimed to answer the following question: "What is the evidence supporting anti-inflammatory properties of metronidazole that are not mediated by its antimicrobial effects?"

METHODS

A scoping review was conducted according to the PRISMA-ScR statement. Five databases were searched up to January 2023 for studies evaluating the anti-inflammatory properties of MTZ used as monotherapy for treating infectious and inflammatory diseases.

RESULTS

A total of 719 records were identified, and 27 studies (21 in vivo and 6 in vitro) were included. The studies reported experimental evidence of MTZ anti-inflammatory effects on (1) innate immunity (barrier permeability, leukocyte adhesion, immune cell populations), (2) acquired immunity (lymphocyte proliferation, T-cell function, cytokine profile), and (3) wound healing/resolution of inflammation.

CONCLUSION

Taken together, this scoping review supported a potential anti-inflammatory effect of MTZ in periodontitis treatment. We recommend that future clinical studies should be conducted to evaluate specific MTZ anti-inflammatory pathways in the treatment of periodontitis.

Long-Term Inflammatory Rosacea Management with Subantibiotic Dose Oral Doxycycline 40 mg Modified-release Capsules Once Daily

BACKGROUND

An important goal of effective rosacea treatment is to maximize the duration of remission.

METHODS

This was a 2-part study. Part 1 was a multicenter, open-label, 12-week study in which adults with moderate or severe inflammatory lesions (papules and pustules) of rosacea received subantibiotic dose oral doxycycline 40mg modified release (SDD₄₀ ) and topical metronidazole gel 1%. Part 2 was a multicenter, randomized, double-blind, placebo-controlled, 40-week study in which successfully treated subjects received once-daily SDD₄₀ or placebo capsules. The primary objective was to assess relapse and efficacy during long-term use of SDD₄₀ versus placebo. Relapse was defined as a return to baseline Investigator Global Assessment (IGA) or lesion count, or any other necessary change in treatment.

RESULTS

Part 1 enrolled 235 subjects. Sixty-five subjects in the SDD₄₀ treatment group and 65 subjects in the placebo group met the definition of treatment success at week 12, and were included in the part 2 analysis. At the end of part 2, half as many subjects in the SDD₄₀ group had relapsed compared to the placebo group (13.8% [n = 9] vs. 27.7% [n = 18], P < .05). Significant differences in the median change in inflammatory lesion counts were also observed (P < .05). Adverse events (AEs) were generally mild-moderate in severity, and most were not treatment-related. Stinging/burning responded with more improvement in subjects treated with SDD₄₀ .

CONCLUSION

After 52 weeks of once-daily treatment, subantibiotic dose doxycycline significantly reduced the relapse rate and inflammatory lesion counts in subjects with moderate-to-severe inflammatory rosacea. This article is protected by copyright. All rights reserved.

Can mesoporous nanoparticles promote bioavailability of topical pharmaceutics?

When applied to skin, particulate matter has been shown to accumulate in hair follicles. In addition to follicles, the skin topography also incorporates trench-like furrows where particles potentially can accumulate; however, the furrows have not been as thoroughly investigated in a drug delivery perspective. Depending on body site, the combined follicle orifices cover up to 10% of the skin surface, while furrows can easily cover 20%, reaching depths exceeding 25 µm. Hence, porous particles of appropriate size and porosity could serve as carriers for drugs to be released in the follicles prior to local or systemic absorption. In this paper, we combine multiphoton microscopy, scanning electron microscopy, and Franz cell diffusion technology to investigate ex-vivo skin accumulation of mesoporous silica particles (average size of 400-600 nm, 2, and 7 µm, respectively), and the potential of which as vehicles for topical delivery of the broad-spectrum antibiotic metronidazole. We detected smaller particles (400-600 nm) in furrows at depths of about 25 µm, also after rinsing, while larger particles (7 µm) where located more superficially on the skin. This implies that appropriately sized porous particles may serve as valuable excipients in optimizing bioavailability of topical formulations. This work highlights the potential of skin furrows for topical drug delivery.

Anti-inflammatory and Immunomodulatory Effects of Antibiotics and Their Use in Dermatology

Antibiotics (antibacterial, antiviral, and antiparasitic) are class of drugs which result in either killing or inhibiting growth and multiplication of infectious organisms. Antibiotics are commonly prescribed by all specialties for treatment of infections. However, antibiotics have hitherto immunomodulatory and anti-inflammatory properties and can be exploited for various noninfectious dermatoses. Dermatologists routinely prescribe antibiotics in treatment of various noninfectious disorders. This study will review anti-inflammatory and immunomodulatory effects of antibiotics and their use in dermatology.

Preparation and evaluation of topical microemulsion system containing metronidazole for remission in rosacea

The aim of this study was to prepare a topical water-in-oil type microemulsion containing metronidazole and to compare its effectiveness with a commercial gel product in the treatment of rosacea. A pseudo-ternary phase diagram (K(m)=2:1) was constructed using lecithin/butanol/isopropyl myristate/water. The microemulsion was chosen from the microemulsion region in the phase diagram. The formulation was a water-in-oil type microemulsion (droplet size: 11.6 nm, viscosity: 457.3 mPa·s, conductivity: 1.5 µs/cm, turbidity: 6.89 NTU) and the addition of the metronidazole did not alter the properties of the system. The release experiment showed that the release rate of metronidazole from the commercial gel product was higher than that of the microemulsion. Stability experiments showed that the metronidazole microemulsion remained stable for at least 6 months; none of the characteristic properties of the microemulsion had changed, the system retained its clarity and there was no sign that crystallization of metronidazole has occurred. Microemulsion was compared to a gel product in a randomized, double-blind, baseline-controlled, split-face clinical trial for the treatment of patients. After the 6-week treatment period there was a statistically significant difference in reduction of the main symptoms of rosacea. Of the patients treated with the microemulsion, 17% experienced complete relief from inflammatory lesions, and 50% from erythema. The microemulsion resulted in complete relief in 38% of the patients with telangiectasia while the commercial product did not provide any relief of telangiectasia symptoms. In conclusion, the microemulsion containing metronidazole was found to be more effective in reducing the symptoms of rosacea compared to the commercial gel product.

Antibiotics used in nonbacterial dermatologic conditions

The majority of nonbacterial dermatological conditions treated with antibiotics benefit from the anti-inflammatory properties of these medications, usually dapsone or tetracycline. Many other antimicrobials are used to treat noninfectious conditions. The following chapter is an overview of select noninfectious dermatological conditions for which antibiotics are used, with a focus on the most common antibiotics used for their nonantimicrobial properties.