Is topical zinc effective in the treatment of melasma? A double-blind randomized comparative study

Different therapeutic approaches in melasma: advances and limitations

Melasma is a chronic hyperpigmentation skin disorder that is more common in the female gender. Although melasma is a multifactorial skin disorder, however, sun-exposure and genetic predisposition are considered as the main etiologic factors in melasma occurrence. Although numerous topical and systemic therapeutic agents and also non-pharmacologic procedural treatments have been considered in melasma management, however, the commonly available therapeutic options have several limitations including the lack of sufficient clinical effectiveness, risk of relapse, and high rate of unwanted adverse drug reactions. Recruitment of nanotechnology for topical drug delivery in melasma management can lead to enhanced skin penetration, targeted drug delivery to the site of action, longer deposition at the targeted area, and limit systemic absorption and therefore systemic availability and adverse drug reactions. In the current review, first of all, the etiology, pathophysiology, and severity classification of melasma have been considered. Then, various pharmacologic and procedural therapeutic options in melasma treatment have been discussed. Afterward, the usage of various types of nanoparticles for the purpose of topical drug delivery for melasma management was considered. In the end, numerous clinical studies and controlled clinical trials on the assessment of the effectiveness of these novel topical formulations in melasma management are summarized.

Best practices in the treatment of melasma with a focus on patients with skin of color

BACKGROUND

Melasma is a chronic hypermelanosis of the skin that affects approximately 1% of the global population, predominantly affects women, and is more prevalent in skin of color. Melasma is a common driver for patients with skin of color to seek out a dermatologist for treatment, and ensuring the right approach for these patients is important because some treatments may be associated with adverse side effects. Because of the chronicity of the disease and established psychosocial and emotional impacts, there is a large need to ensure care follows the best available evidence on the treatment of patients with melasma.

OBJECTIVE

Here, we summarized current available topical treatments for melasma with considerations dermatologists should have for their patients with skin of color.

METHODS

Steering committee consensus on clinical best practices.

RESULTS

We describe a flexible and focused treatment algorithm that reflects both treatment and maintenance periods that is a consensus of our extensive clinical experience.

LIMITATIONS

Use of real-world evidence and potential for individual practice bias.

CONCLUSION

Melasma can be challenging to treat, particularly in patients with skin of color, and our recommendations for best practices for patients in the United States are an important step toward standardizing care.

The Impact of Antioxidants on Vitiligo and Melasma: A Scoping Review and Meta-Analysis

Reactive oxygen species (ROS) generated during melanogenesis make melanocytes particularly vulnerable to oxidative stress, influencing their survival and melanin synthesis. Oxidative stress, significantly present in vitiligo and recently also detected in melasma, triggers inflammatory cascades and melanogenesis, making antioxidants a promising therapeutic avenue. A systematic search was conducted on Embase and Pubmed to study the efficacy of antioxidants for treating vitiligo and/or melasma. Meta-analysis was performed to assess the difference in Melasma Severity Index (MASI) scores between baseline and follow-up. Various antioxidants like polypodium leucotomos, ginkgo biloba, catalase/superoxide dismutase, and vitamin E have potential in vitiligo. For melasma, vitamin C, silymarin, and niacinamide were among those showing promise in reducing pigmentation, with vitamin C displaying significant effects in meta-analysis. Different antioxidants improve both vitiligo and melasma, with an increased minimal erythema dose (MED) following UV exposure being significant for vitiligo and tyrosinase inhibition being crucial for melasma. However, the efficacy of individual antioxidants varies, and their exact mechanisms, especially in stimulating melanocyte proliferation and anti-inflammatory pathways, require further investigation to understand better and optimize their use.

Analysis of the antimelanogenic activity of zinc and selenium in vitro

Melasma is an acquired chronic condition characterized by hyperchromic patches in photo-exposed areas. The search for new compounds for the treatment of melasma without side effects is constant. In this context, the aim of this study was to investigate the in vitro cytotoxic and antimelanogenic effects of the trace elements Zinc (Zn) and Selenium (Se). In this study, we evaluated the effects of 30 µM hydroquinone, this concentration did not alter mitochondrial function (MTT assay), but increased the percentage of necrotic cells and levels of reactive species. Furthermore, it showed no influence on tyrosinase activity and melanin content. Unlike hydroquinone, exposure for 48 h to 100 µM Zn and 1 and 5 µM Se had no significant influence on the analysis of reactive species, as well as on the percentage of necrotic cells. Still, specifically in relation to 100 µM Zn, it decreased the melanin content. Given the above, the trace elements Zn and Se did not show toxicity at the concentrations tested and Zn showed a promising effect, however, the mechanism needs to be better explored in order to contribute to new and updated research in the fight against melasma with a perspective of therapeutic use.

Topical and Systemic Therapies in Melasma: A Systematic Review

Introduction

Melasma is an acquired disorder, which presents with well-demarcated, brown-colored hyperpigmented macules, commonly involving the sun-exposed areas such as the face. It is a chronic and distressing condition, affecting the patients' quality of life, and has been conventionally treated with "first-line" agents including hydroquinone (HQ) alone or as a part of a triple combination cream (TCC), while "second-line" options include chemical peels, and third line options include laser therapy.

Materials and Methods

A systematic search was performed for all topical and systemic treatments for melasma up till May 4, 2021, using the PubMed and EMBASE databases, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. The search terms "melasma" and "treatment" were used to search for the relevant articles on both these databases, and a total of 4020 articles were identified. After removing the duplicate entries and screening the titles, abstracts, and full-text articles, we identified 174 randomized controlled trials (RCTs) or controlled clinical trials.

Results

Based on our review, HQ, TCCs, sunscreens, kojic acid (KA), and azelaic acid receive grade A recommendation. Further large-scale studies are required to clearly establish the efficacy of topical vitamin C, resorcinol, and topical tranexamic acid (TXA). Several newer topical agents may play a role only as an add-on or second-line drugs or as maintenance therapy. Oral TXA has a strong recommendation, provided there are no contraindications. Procyanidins, Polypodium leucotomos (PL), and even synbiotics may be taken as adjuncts.

Discussion

Several newer topical and systemic agents with multimodal mechanisms of action have now become available, and the balance seems to be tipping in favor of these innovative modalities. However, it is worth mentioning that the choice of agent should be individualized and subject to availability in a particular country.

Trace element zinc and skin disorders

Zinc is a necessary trace element and an important constituent of proteins and other biological molecules. It has many biological functions, including antioxidant, skin and mucous membrane integrity maintenance, and the promotion of various enzymatic and transcriptional responses. The skin contains the third most zinc in the organism. Zinc deficiency can lead to a range of skin diseases. Except for acrodermatitis enteropathic, a rare genetic zinc deficiency, it has also been reported in other diseases. In recent years, zinc supplementation has been widely used for various skin conditions, including infectious diseases (viral warts, genital herpes, cutaneous leishmaniasis, leprosy), inflammatory diseases (hidradenitis suppurativa, acne vulgaris, rosacea, eczematous dermatitis, seborrheic dermatitis, psoriasis, Behcet's disease, oral lichen planus), pigmentary diseases (vitiligo, melasma), tumor-associated diseases (basal cell carcinoma), endocrine and metabolic diseases (necrolytic migratory erythema, necrolytic acral erythema), hair diseases (alopecia), and so on. We reviewed the literature on zinc application in dermatology to provide references for better use.

Efficacy and safety of topical agents in the treatment of melasma: What's evidence? A systematic review and meta-analysis

BACKGROUND

Various topical agents have been used to treat melasma; however, a large-scale evaluation among the currently available treatment is lacking.

OBJECTIVES

The aim of this study was to evaluate the efficacy and safety of topical agents for melasma.

METHODS

The MEDLINE, Embase, Web of Science, Cochrane, and Alt-Healthwatch databases were searched in November 2021. Original studies that reported pre- and post-treatment Melasma Area Severity Index (MASI)/modified Melasma Area Severity Index (mMASI) scores and/or adverse effects (AEs) were eligible for inclusion. The main outcome was the efficacy analyzed by the changes in the pre- and post-treatment with standardized mean difference (SMD) of MASI/mMASI scores; the AEs were calculated with incidence proportion by the reported percentage of skin irritations.

RESULTS

A total of 45 studies (2359 patients) and 55 studies (4539 patients) met the inclusion criteria for efficacy and AEs, respectively. Hydroquinone (HQ) monotherapy (SMD -1.3, 95% CI [-1.6 to -1.0]), HQ-containing combination therapy (-1.4, [-1.7 to -1.1]), cysteamine (-1.6, [-2.0 to -1.2]), tranexamic acid (-1.5, [-2.0 to -1.1]), azelaic acid (-1.3, [-1.7 to -1.0]), and kojic acid (-0.9, [-1.3 to -0.5]) demonstrated comparable efficacy, while zinc sulfate did not exhibit statistically significant improvement (-1.2, [-2.7 to 0.4]). HQ-containing combination therapy (50.9%) and cysteamine (42.2%) demonstrated the highest incidence of irritation, while azelaic acid (18.7%), kojic acid (5.3%), and tranexamic acid (0.8%) revealed a lower risk.

CONCLUSIONS

In this meta-analysis, non-HQ agents except zinc sulfate may be considered as an alternative to HQ-containing agents. However, treatment should be guided by patient's tolerance, availability, and physicians' experience.

Understanding Melasma-How Can Pharmacology and Cosmetology Procedures and Prevention Help to Achieve Optimal Treatment Results? A Narrative Review

Melasma is a chronic skin condition that involves the overproduction of melanin in areas exposed to ultraviolet radiation. Melasma treatment is long-term and complicated with recurrence and resistance to treatment. The pathogenesis of melasma is highly complex with multiple pathologies occurring outside of the skin pigment cells. It includes photoaging, excessive melanogenesis, an increased number of mast cells, increased vascularization, and basement membrane damage. In addition, skin lesions related to melasma and their surrounding skin have nearly 300 genes differentially expressed from healthy skin. Traditionally, melasma was treated with topical agents, including hydroquinone, tretinoin, glucocorticosteroids and various formulations; however, the current approach includes the topical application of a variety of substances, chemical peels, laser and light treatments, mesotherapy, microneedling and/or the use of systemic therapy. The treatment plan for patients with melasma begins with the elimination of risk factors, strict protection against ultraviolet radiation, and the topical use of lightening agents. Hyperpigmentation treatment alone can be ineffective unless combined with regenerative methods and photoprotection. In this review, we show that in-depth knowledge associated with proper communication and the establishment of a relationship with the patient help to achieve good adherence and compliance in this long-term, time-consuming and difficult procedure.

Treatment of melasma: a review of less commonly used antioxidants

Melasma, a common cause for seeking dermatologic care, is a chronic condition of skin hyperpigmentation. With a poorly understood pathogenesis, and no universal cure, melasma is a challenge for many dermatologists. For decades, there has been investigation into the role of oxidative stress in melasma. In this literature review, we introduce the role of oxidative stress in melasma and discuss the function of various topical and oral antioxidant therapies for patients suffering from melasma. Numerous studies have shown efficacy of various antioxidant therapies for treatment of hyperpigmentation, and in this review, we focus primarily on those with less widespread use. Vitamin E, niacinamide, polypodium leucotomos, pycnogenol, grape seed extract, amino fruit acids, phytic acid, zinc, silymarin, Korean red ginseng powder, plant extracts, and parsley all have well-demonstrated evidence of antioxidant properties, and these substances have been studied in the context of skin hyperpigmentation. Although there is conflicting evidence of their therapeutic efficacy, the use of these naturally occurring substances is promising for patients and medical providers seeking alternative therapeutic options.

Melasma Treatment: An Evidence-Based Review

BACKGROUND

Melasma is an acquired, chronic pigmentary disorder predominantly affecting women. It may significantly affect quality of life and self-esteem due to its disfiguring appearance. Multiple treatments for melasma are available, with mixed results.

OBJECTIVE

The aim of this article was to conduct an evidence-based review of all available interventions for melasma.

METHODS

A systematic literature search of the PubMed electronic database was performed using the keywords 'melasma' and/or 'chloasma' in the title, through October 2018. The search was then limited to 'randomized controlled trial' and 'controlled clinical trial' in English-language journals. The Cochrane database was also searched for systematic reviews.

RESULTS

The electronic search yielded a total of 212 citations. Overall, 113 studies met the inclusion criteria and were included in this review, with a total of 6897 participants. Interventions included topical agents, chemical peels, laser- and light-based devices, and oral agents. Triple combination cream (hydroquinone, tretinoin, and corticosteroid) remains the most effective treatment for melasma, as well as hydroquinone alone. Chemical peels and laser- and light-based devices have mixed results. Oral tranexamic acid is a promising new treatment for moderate and severe recurrent melasma. Adverse events from all treatments tend to be mild, and mainly consist of skin irritation, dryness, burning, erythema, and post-inflammatory hyperpigmentation.

CONCLUSIONS

Hydroquinone monotherapy and triple combination cream are the most effective and well-studied treatments for melasma, whereas chemical peels and laser- and light-based therapies are equal or inferior to topicals, but offer a higher risk of adverse effects. Oral tranexamic acid may be a safe, systemic adjunctive treatment for melasma, but more studies are needed to determine its long-term safety and efficacy. Limitations of the current evidence are heterogeneity of study design, small sample size, and lack of long-term follow-up, highlighting the need for larger, more rigorous studies in the treatment of this recalcitrant disorder.

Evaluation of the serum zinc level in adult patients with melasma: Is there a relationship with serum zinc deficiency and melasma?

BACKGROUND

Melasma is a common acquired hypermelanosis of sun-exposed skin, particularly on the face, which presents as symmetric, light- to gray-brown-colored macules and patches. There are several studies of serum zinc levels in cutaneous disorders. So far, no studies have been carried out to assess the serum zinc level in patients with melasma. The aim of this study is to determine the serum zinc level in patients with melasma compared to healthy subjects.

MATERIALS AND METHODS

A total of 118 patients with melasma and 118 healthy controls were enrolled in this prospective cross-sectional study. The two groups were matched for age and sex. Atomic absorption spectrophotometry was used to measure serum zinc levels. The statistical analysis was performed using SPSS software.

RESULTS

The mean serum level of zinc in melasma patients and controls was 77.4±23.2 μg/dL and 82.2±23.9 μg/dL, respectively (P-value=.0001). Serum zinc deficiency was found in 45.8% and 23.7% of melasma patients and control subjects, respectively. A positive family history of melasma in first-degree relatives was present in 46 (39%) of the cases, and a history of taking oral contraceptive pill was found in 95 (81%) of women with melasma. The aggravating factors for melasma were stated as: sun exposure (11.1%), pregnancy (15.3%), nutrition (2.5%), oral contraceptive pills (18.6%), and emotional stress (5.9%). The malar and centrofacial patterns were seen in 3.4% and 72% of cases, respectively, whereas 24.6% of the patients had both centrofacial distribution and malar distribution, and there was no patient with mandibular pattern. Among patients with melasma, 20.3% had thyroid dysfunction, while in the control subjects, 8.4% had thyroid dysfunction (P=.001).

CONCLUSION

There is a significant relationship between low levels of zinc and melasma. Zinc deficiency may be involved in the pathogenesis of melasma. Also, treatment with oral zinc supplements can be tried in these patients to see the outcome. However, to make recommendations on screening for zinc deficiency in patients with melasma, future research of good methodological quality is needed.

Involvement of Transient Receptor Potential Cation Channel Member A1 activation in the irritation and pain response elicited by skin-lightening reagent hydroquinone

Hydroquinone (HQ) is one of the most frequently used and effective skin-lightening products to treat skin hyperpigmentation disorders, including postinflammatory hyperpigmentation, melasma and solar lentigines. HQ is also widely used in cosmetic products for skin whitening. However, HQ treatment can evoke substantial skin irritation, a side effect that remains poorly understood. Here we demonstrate that HQ is an activator of the peripheral irritant receptor transient receptor potential (TRP) cation channel member A1 (TRPA1). HQ failed to activate TRPV1, TRPV4 or TRPM8. HQ-induced TRPA1 activation was dependent on essential redox-sensitive cysteine and lysine residues within N-terminus of channel protein. HQ elicited Ca²⁺ influx in a subpopulation of mouse sensory neurons sensitive to the TRPA1 agonist, mustard oil. HQ-induced neuronal responses were significantly reduced by TRPA1 inhibitors, and reduced in neurons isolated from Trpa1-deficient mice. In mice, intraplantar injection of HQ at clinically relevant concentrations elicited both acute pain and persistent mechanical hyperalgesia which were almost completely abolished by TRPA1 inhibitors. These findings identify TRPA1 as a molecular target for HQ and provide insights into the mechanism of HQ-induced skin irritation. These findings also suggest that selective TRPA1 antagonists may be useful to counteract HQ-induced skin irritation.

Statistical reporting in randomized controlled trials from the dermatology literature: a review of 44 dermatology journals

BACKGROUND

The validity of randomized controlled trials (RCTs) is determined by several statistical factors.

OBJECTIVES

To determine the level of recent statistical reporting in RCTs from the dermatology literature.

METHODS

We searched MEDLINE for all RCTs published between 1 May 2013 and 1 May 2014 in 44 dermatology journals.

RESULTS

Two hundred and ten articles were screened, of which 181 RCTs from 27 journals were reviewed. Primary study outcomes were met in 122 (67.4%) studies. Sample size calculations and beta values were reported in 52 (28.7%) and 48 (26.5%) studies, respectively, and nonsignificant findings were supported in only 31 (17.1%). Alpha values were reported in 131 (72.4%) of studies with 45 (24.9%) having two-sided P-values, although adjustment for multiple statistical tests was performed in only 16 (9.9% of studies with ≥ two statistical tests performed). Sample size calculations were performed based on a single outcome in 44 (86.3%) and multiple outcomes in six (11.8%) studies. However, among studies that were powered for a single primary outcome, 20 (45.5%) made conclusions based on multiple primary outcomes. Twenty-one (41.2%) studies relied on secondary/unspecified outcomes. There were no differences for primary outcome being met (Chi-square, P = 0.29), sample size calculations (P ≥ 0.55), beta values (P = 0.89), alpha values (P = 0.65), correction for multiple statistical testing (P = 0.59), two-sided alpha (P = 0.64), support of nonsignificant findings (Fisher's exact, P = 0.23) based on the journal's impact factor.

CONCLUSIONS

Levels of statistical reporting are low in RCTs from the dermatology literature. Future work is needed to improve these levels of reporting.

Zinc therapy in dermatology: a review

Zinc, both in elemental or in its salt forms, has been used as a therapeutic modality for centuries. Topical preparations like zinc oxide, calamine, or zinc pyrithione have been in use as photoprotecting, soothing agents or as active ingredient of antidandruff shampoos. Its use has expanded manifold over the years for a number of dermatological conditions including infections (leishmaniasis, warts), inflammatory dermatoses (acne vulgaris, rosacea), pigmentary disorders (melasma), and neoplasias (basal cell carcinoma). Although the role of oral zinc is well-established in human zinc deficiency syndromes including acrodermatitis enteropathica, it is only in recent years that importance of zinc as a micronutrient essential for infant growth and development has been recognized. The paper reviews various dermatological uses of zinc.