weeks 4, 6 and 8, the triple combination cream was significantly
more effective than hydroquinone cream alone, while both groups had a similar incidence of irritation.19 Another trial of 247 East and Southeast Asians with moderate-to-severe melasma
compared, once again, triple combination cream applied once daily to hydroquinone 4% cream applied twice daily. After eight weeks of treatment, 64 percent of the subjects receiving
triple combination therapy had a melasma global severity score of "none" or "mild" compared with 39 percent in the hydroquinone
group. Although treatment-related adverse events occurred more frequently in the triple combination group (48%) compared with the hydroquinone group (14%), most of these were mild in intensity.20 In subjects with Fitzpatrick skin types I to IV, triple combination has also been shown to be more effective than various combinations of dual therapy for the treatment of melasma.21
Chemical peels are occasionally used to improve melasma in lighter-skinned individuals; however, these agents should be used with caution in darker-skinned patients as they have a greater tendency to induce pigmentary changes.15 A trial of 50 East Indian subjects found that hydroquinone is superior to tretinoin as a priming agent in maintaining the results achieved with peels and in decreasing the incidence of post-peel reactive hyperpigmentation.22
Based on the literature and our personal experience, topical retinoids
are best used in the setting of combination therapy with topical steroids and hydroquinone for the short-term treatment of melasma and are generally well tolerated across a wide range of racial groups.
Retinoids prevent the formation of microcomedones and eradicate
existing comedones by increasing the production of loose, non-coherent horny cells in the follicular orifice.23 Furthermore,these agents possess direct anti-inflammatory and anti-fibroblastic
properties, which make them effective inhibitors of the key pathogenic pathways responsible for PIH and keloids.24
As sequelae of acne, PIH and keloidal scarring are more likely to occur in darker-skinned patients.24 Despite the clinical presentation
of acne being generally milder in patients with darker skin types, it is characterized by marked inflammation histologically.
25 This may explain why PIH associated with acne is more common in pigmented skins.
Several studies have looked at the role of topical retinoids in treating acne in pigmented skins. An eight week trial of topical tretinoin 0.025% cream in 27 black subjects with acne found a significant reduction in papules, pustules and hyperpigmented macules occurring in 83 percent of subjects treated with tretinoin
in comparison to only 13 percent receiving vehicle alone. Many of the subjects in this study experienced irritation; however,
the severity was classified as minimal.1 This was not a randomized controlled study; that is a weakness of this trial.
A 12-week study of topical adapalene 0.1% gel applied daily was conducted in 65 African black subjects with mild-to-moderate
acne. Adapalene was shown to be effective against both inflammatory and non-inflammatory lesions. Furthermore, approximately
two-thirds of subjects were rated as having less post-inflammatory hyperpigmentation after 12 weeks. Less than five percent of subjects reported moderate or severe skin irritation at any time during the study. Interestingly, the incidence
of moderate-to-severe skin oiliness decreased from 66 percent at baseline to complete absence in all subjects after 12 weeks of treatment.26 This was also not a randomized placebo controlled study, which poses a weakness.
A meta-analysis of five randomized U.S. and European studies on adapalene was conducted to further assess the safety and efficacy of adapalene in black versus Caucasian subjects with