Metronidazole, its bioactive metabolites and acne

New Molecules of Importance in the Prevention and Treatment of Acne: A Systematic Patent Review (2016-2020)

BACKGROUND

Acne is a highly prevalent disease that mainly affects the pilosebaceous units associated with sebaceous glands, causing inflammatory skin lesions and affecting the self-esteem, mental health, and quality of life of those who suffer from this disease. Different treatments exist today to prevent, reduce, and improve symptoms; however, over the years, there have been problems with bacterial resistance and slight effectiveness with prolonged use.

OBJECTIVE

The purpose of this article is based on the review of patents of new products of principal topical administration for the treatment of acne in recent years 2016-2020, to evaluate and analyze novel synthetic molecules and semi-synthetics with potential therapeutic and preventive in the acne treatment.

METHODS

A systematic review of patents was conducted through the official database of the European Patent Office - Espacenet, where the search focused on the keywords: "acne and bacteria" in the title or abstract. Only patents granted between the years 2016-2020 were included, with products having molecules with a synthetic and semi-synthetic origin, without considering natural, biological products or those used as diagnostic means.

RESULTS

A total of 19 patents were selected, most with principally antimicrobial and antiinflammatory action, where the reduction in the appearance of resistance by C. acnes is verified, and its action is complemented by inhibiting the different pathophysiological mechanisms that lead to the worsening of the disease.

CONCLUSION

Novel approaches in the treatment and prevention of acne, mainly topically, are focused on the reduction of bacterial resistance and irritation compared to current treatments. The use of combined formulations provides better results with additional benefits, improving treatment times and patient adherence.

A Rationally Designed Multifunctional Antibiotic for the Treatment of Drug-Resistant Acne

Acne is a multifactorial skin disease, underpinned by colonization of Propionibacterium acnes and inflammation. The emergence of resistant P. acnes strains has affected the current acne treatment algorithm. This setback served as an impetus for rationally designing a library of next-generation antibiotics that exhibit a bactericidal effect on resistant P. acnes and exert an immunomodulatory function to reduce inflammation. In silico screening showed that one of the molecules, VCD-004, exhibits improved mode of binding to bacterial DNA gyrase. VCD-004 shows high potency against clinical isolates of resistant P. acnes and excellent efficacy in vivo. Furthermore, VCD-004 exhibits a superior mutant prevention index, suggesting that it impedes the development of resistance better than clindamycin. Additionally, it shows optimal skin penetration and has a potent anti-inflammatory effect via reduction of proinflammatory cytokines (IL-6) independent of its antibacterial action. VCD-004 affects P. acnes-induced nuclear accumulation of NF-κB in THP-1 cells. The in vitro viability of human keratinocytes in the presence of VCD-004 indicates a desirable therapeutic window for topical use. Such rationally designed bactericidal and immunomodulatory dual pharmacophore-based lipophilic molecule(s) can emerge as the next-generation topical therapy for acne with underlying resistant P. acnes etiology.

Efficacy of 2% metronidazole gel in moderate acne vulgaris

BACKGROUND

Acne vulgaris is an inflammatory disease of the pilosebaceous units. Various systemic and topical options are available for its treatment.

AIMS

This study aimed to evaluate the efficacy of 2% metronidazole gel in acne vulgaris.

MATERIALS AND METHODS

Double-blind, randomized, placebo-controlled, split-face clinical trial. Seventy young adults with moderate acne vulgaris received 2% metronidazole gel on the right side of their face and placebo on the left side of their face twice daily for 8 weeks. The number of inflamed and noninflamed facial lesions and side effects of treatment were documented on weeks 1, 2, 4, and 8. The patients' overall satisfaction was recorded at the end of the study. For statistical analysis we used the repeated-measures analysis, the chi-square test, Fisher's exact test, and the independent-samples t-test as appropriate.

RESULTS

Counts of inflamed and noninflamed facial lesions were comparable between the two sides at baseline. The number of the lesions was significantly lower on the metronidazole-treated side at all follow-up visits. Erythema and oily face decreased by 85.7% and 87.1%, respectively, on the metronidazole-treated side. Mild burning sensation and dryness on the metronidazole-treated side was reported by 3.4% and 22.9% of the patients, respectively. Eighty-eight percent of the patients were satisfied with the results of treatment on the metronidazole-treated side.

CONCLUSIONS

Metronidazole gel (2%) is an effective, safe, and well-tolerated topical medication for moderate acne vulgaris.

Oral azithromycin for treatment of intractable rosacea

Rosacea is a common chronic cutaneous disorder that primarily occurs on the convex surfaces of the central face and is often characterized by exacerbations and remissions. A case of a 52-yr-old woman visited our clinic in February 2008 complaining typical features of rosacea including multiple pinhead to rice-sized erythematous papules. We applied various conventional treatments including topical benzoyl peroxide and metronidazole as well as oral metronidazole, isotretinoin, and doxycycline. The lesions were not controlled but were rather aggravated by complications from these treatments. Therefore, we prescribed oral azithromycin, which has anti-inflammatory effects and reduces reactive oxygen species. Ten weeks after the administration of oral azithromycin, 500 mg per day for 2 weeks, the lesions had mostly disappeared and no specific side effects related to the azithromycin were noted. Oral azithromycin dosing 500 mg/day for 2 weeks is effective for treatment of intractable rosacea.

Ocular Rosacea

Rosacea is a common skin disease that frequently involves the eye. Although the pathogenesis of the disease remains undefined, recent findings suggest that an altered inflammatory response plays an important role in both cutaneous and ocular rosacea. Ocular manifestations include lid and ocular surface alterations. Chronic inflammation can lead to corneal vascularization, which may compromise vision. Treatment of ocular rosacea is aimed at preventing irritation of the ocular surface (e.g., lubricants, lid hygiene) and controlling inflammation with topical and systemic anti-inflammatory drugs. Systemic tetracyclines are the mainstay of treatment. These drugs act multifactorially by decreasing bacterial flora and the expression of matrix metalloproteinases, altering meibum secretion, inhibiting the production of bacterial lipases, and providing an immunomodulatory effect.

Therapeutic potential of azithromycin in rosacea

BACKGROUND

Systemic antibiotics currently used in the treatment of rosacea are sometimes associated with uncomfortable side-effects. Therefore, a need for an effective agent with few side-effects and good patient compliance exists. Azithromycin, a macrolide antibiotic with prolonged mode of action, has recently been found to be an effective alternative in the treatment of inflammatory acne. We planned a study to evaluate the efficacy and safety of azithromycin in rosacea.

METHODS

An open-labeled study was performed in a population of 18 patients, with Plewig-Kligman stage 2 rosacea. Patients were given oral azithromycin for 12 weeks in decreasing doses.

RESULTS

Fourteen subjects completed the trial. The treatment produced therapeutic benefits with regard to total scores as well as inflammatory lesion scores. At the end of 12 weeks, there was a 75% decrease in total scores (P < 0.001) and an 89% decrease in inflammatory lesion scores compared with basal values. Improvement continued during the 4 weeks after treatment. Adverse effects were minimal and well tolerated in most patients.

CONCLUSION

Azithromycin is a promising agent in the treatment of rosacea with its few side-effects and good patient compliance.

The management of rosacea

Rosacea is a multiphasic disease which is associated with flushing, erythrosis, papulopustular rosacea and phymas; each phase is likely to have its own treatment. Flushing is better prevented rather than treated, and its etiology investigated. Beta-blockers, atenolol in particular, are worthy of prophylactic trials examining their efficacy in treating the flushing associated with rosacea. Currently, clonidine is the only drug available for the treatment of flushing. Treatment for erythrosis includes topical and systemic therapies. Metronidazole 1% cream and azelaic acid 20% cream have been reported to reduce the severity score of erythema. The systemic treatment of erythrosis is based on the association of Helicobacter pylori with rosacea. However, this role is still being debated. Eradication of H. pylori can be achieved using a triple therapy regimen lasting 1 to 2 weeks [omeprazole and a combination of two antibacterials (a choice from clarithromycin, metronidazole or amoxicillin)]. Both the flashlamp-pumped long-pulse dye laser and the potassium-titanyl-phosphate laser may be used in the treatment of facial telangiectases. Both systemic and topical remedies may be used to treat the papulopustules of rosacea. Systemic treatment includes metronidazole, doxycycline, minocycline, clarithromycin and isotretinoin, while topical treatment is based on metronidazole cream and gel. The presence of Demodex folliculorum is important in the inflammatory reaction, whether it is pathogenetic or not. Crotamiton 10% cream or permethrin 5% cream may be useful medications for papulopustular rosacea, although they are rarely successful in eradicating D. folliculorum. Oral or topical ivermectin may also be useful in such cases. Ocular involvement is common in patients with cutaneous rosacea and can be treated with orally administered or topical antibacterials. Once rhinophyma starts to be evident, the only way to correct it is by aggressive dermatosurgical procedures. Decortication and various types of lasers can also be used. Associated conditions, such as seborrheic dermatitis and possible contact sensitizations, deserve attention.