Topical Treatments for Melasma
In those patients with epidermal type melasma, there are multiple treatments available (see Table 2 ).[6] Topical agents include phenols, e.g., hydroquinone (HQ); retinoids, e.g., tretinoin; azelaic acid; kojic acid (KA); and glycolic acid (GA).
Hydroquinone
HQ 2%-4% has been widely used for melasma therapy. It inhibits the conversion of dopa to melanin by inhibiting the activity of tyrosinase.[13] Moreover, Jimbow, et al. proposed that it may interfere with DNA and RNA synthesis, degrade melanosomes, and destroy melanocytes.[14]
There are rare case reports of allergic contact dermatitis to HQ,[15,16,17] however, irritant reactions are more common, with up to 25% developing an itchy eruption as demonstrated in a recent randomized control trial.[18] We recommend that patients test HQ on a hidden area, e.g., the upper inner arm, prior to use on areas that are especially visible, such as the face.
Ennes, et al. compared HQ 4% with placebo over 12 weeks in 48 patients who had melasma. Thirty-eight percent of HQ patients showed total improvement and 57% demonstrated partial improvement. Only 8% of placebo patients achieved total improvement and 17% were treatment failures.[19] Side-effects included irritant and allergic contact dermatitis, PIH, nail bleaching and rarely, ochronosis-like pigmentation.[8] Toxicity studies have shown HQ is capable of inducing renal adenoma in rats and is fetotoxic in animals.[20] These findings influenced the EU to ban HQ agents as a cosmetic. However, these complications have not been reported in humans.[21]
Under no circumstances should monobenzylether, or any other ethers of HQ, be used to treat melasma as they can lead to a permanent loss of melanocytes with the development of a disfiguring confetti-like leukoderma.[7]
Retinoids
Tretinoin 0.05%-0.1% reduces pigmentation by inhibiting tyrosinase transcription, as well as by interrupting melanin synthesis.[22] While tretinoin may be effective in reducing melasma, it typically takes at least 24 weeks to see clinical improvement.[23] It may also increase pigmentation secondary to irritation[10] and may cause erythema and peeling.[24] Other retinoids including adapalene, tazarotene and topical isotretinoin have also been used.[25,26]
Azelaic Acid
Azelaic acid (15%-20%) (Finacea®, Intendis), a C9 dicarboxylic acid, is a reversible inhibitor of tyrosinase[27] and may also have both cytotoxic and antiproliferative effects on melanocytes.[28] In a randomized, double-blind study, azelaic acid was shown to be as effective as HQ 4% but without its side effects.[29] The combination of azelaic acid with 0.05% tretinoin or 15%-20% glycolic acid may produce earlier, more pronounced skin lightening.[8] Adverse effects include pruritus, mild erythema, scaling, and burning.[28]
Kojic Acid
KA 2% is produced by the fungus Aspergilline oryzae and is a tyrosinase inhibitor.[7] It is generally equivalent to other therapies but may be more irritating.[30] In one double-blind study, KA 2% combined with HQ 2% was shown to be superior to glycolic acid (GA) 10% and HQ 2%.[31] Another double-blind study compared GA 5% with either HQ 4% or KA 4% for 3 months. Both combinations proved equally effective with reduction of pigmentation in 51% of patients.[32] KA may be effective if a patient has difficulty tolerating other first-line therapies.[30]
Glycolic Acid
GA 5%-10% is an alpha-hydroxy acid and has been studied in combination with other agents. It decreases pigment by many mechanisms including thinning the stratum corneum, enhancing epidermolysis, dispersing melanin in the basal layer of the epidermis, and increasing collagen synthesis in the dermis.[2] One combination study compared GA 10% plus HQ 4% in a cream that included vitamins C and E and sunscreen vs. sunscreen cream alone. Seventy-five percent of patients improved using the treatment enhanced cream compared with only 13% who used the sunscreen alone. Mild irritation was a common adverse effect.[33]
Combination Therapy
Combination therapy is more effective than single agents used alone. The etiology of melasma is not completely understood, thus, therapies that can act at different stages of pigmentation can produce better clinical results than a single therapy acting at a single stage.[6]
The addition of tretinoin eliminates pigment and increases keratinocyte proliferation by preventing the oxidation of HQ and improving epidermal penetration. Further, adding topical corticosteroids reduces the irritative effects of hypopigmenting agents, and inhibits melanin synthesis by decreasing cellular metabolism.[6] This combination, HQ 5%, tretinoin 0.1%, and dexamethasone 0.1%, was first introduced in 1975 and termed the Kligman formula after its inventor. It has been the most extensively used combination therapy for melasma worldwide.[34]
More recently, results from a multicenter, randomized, double-blind control trial demonstrated that a new combination of HQ 4%, tretinoin 0.05%, and fluocinolone acetonide 0.01% (Tri-Luma®, Galderma) proved better than any combination of two of the above agents, with 77% of patients showing complete or nearly complete clearing. Clinically significant improvement was noted as early as 4 weeks with maximum results at 8 weeks. The most common adverse effects were mild local irritation, erythema, and skin peeling.[35] The mixture should be applied to the entire affected area to avoid blotchiness. The recent 2006 consensus of the Pigmentary Disorders Academy (PDA), a group of international dermatologists and leaders in pigmentary disorders who receive sponsorship from Galderma, supported the use of triple therapy.
The PDA consensus suggested that first-line therapy for melasma should consist of fixed topical therapies and only when triple combination therapy is unavailable or patients have a sensitivity to the ingredients, should dual ingredients or single agents be considered.[6]
Over-the-Counter Products
Over-the-counter (OTC) products are readily available, and many patients have already tried these measures prior to consulting a dermatologist. At the present time the available concentrations of HQ for OTC use are not as efficacious as prescription formulations.[36] Alpha and beta hydroxy acid home chemical peels and topical vitamin A are also available.
The combination of N-acetyl glucosamine (NAG) and niacinamide (Olay® Definity®) was recently shown to reduce facial hyperpigmentation in Japanese and Caucasian subjects with facial hyperpigmentation in two double-blind, vehicle-controlled, split-face, left-right randomized clinical studies.[37] In another double-blind, vehicle-controlled, full-face clinical study, a significant reduction in facial hyperpigmented spots was seen in patients with facial hyperpigmentation using the NAG 2% + niacinamide 4% formulation when compared with the vehicle regimen.[38] There were no adverse effects reported.
Miscellaneous Treatments
Other topical therapies have been used including ascorbic acid, licorice extract and, in the past, mercury.[6]
Treatment During Pregnancy
Treatment of melasma in pregnant women is routinely deferred until after delivery. This is because, first of all, melasma is more resistant to treatment because the hormonal trigger for it persists throughout pregnancy.[39] Second, therapy may be unnecessary since most women have a significant improvement in melasma after parturition. Third, therapy for melasma is contraindicated during pregnancy.
Treatment of PIH
Initial treatments for PIH should, if possible, manage and control the underlying skin condition.[10] To lower the risk of PIH in patients with inflammatory conditions such as acne and atopic dermatitis, they should present early to a physician. As with melasma, sunscreen and sun avoidance are extremely important. Other treatment options are similar to those discussed above for melasma.[2] A clinical trial evaluated the effects of 0.1% tretinoin cream on PIH in patients with Type VI skin. Although significant lightening effects were seen, 50% of patients in the treatment group experienced moderate dermatitis.[40]
Another PIH treatment study observed the addition of GA peels to a topical regimen of HQ 2%, GA 10% and tretinoin 0.05% cream in PIH patients with Type VI skin. This study showed improvement with peels and minimal adverse effects.[41] However, as mentioned earlier, caution must be taken when performing peels on darker skinned patients because there is a higher risk of hyperpigmentation.[30]
Skin Therapy Letter. 2006;11(9):1-6. © 2006 SkinCareGuide.com
Cite this: Topical Treatments for Melasma and Postinflammatory Hyperpigmentation - Medscape - Nov 01, 2006.
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