Topical Retinoids for Pigmented Skin

acne. In black subjects, adapalene exhibited efficacy in the reduction of inflammatory lesions and better tolerability, as seen by a decreased frequency of erythema and scaling, compared to Caucasians.²⁷

Adapalene gel 0.1% has also been proven efficacious and well tolerated in the treatment of acne in Asian populations. The efficacy and safety of adapalene gel 0.1% versus the corresponding gel vehicle for a period of 12 weeks has been evaluated in 200 Japanese subjects. The median percent reduction of total acne lesion counts at endpoint was significantly greater in the adapalene gel 0.1% group (63.2%) versus the vehicle group (36.9%). Adapalene was well tolerated in these subjects and the adverse events, most commonly dry skin, were classified as transient and mild-to-moderate in severity.²⁸ Similarly, an eight-week study of adapalene 0.1% gel versus tretinoin 0.025% gel in 150 Chinese subjects with mild-to-moderate acne vulgaris determined that adapalene 0.1% gel was equally effective as tretinoin 0.025% gel for acne lesions, with a more favorable tolerability profile.²⁹ This trial is particularly noteworthy because it offers a rare direct comparison between topical retinoids for acne in pigmented skins.

A study of 126 East Indian subjects with acne vulgaris evaluated the efficacy and safety of tazarotene 0.1% gel daily for 14 weeks.³⁰ A statistically significant reduction was observed at weeks 8 and 12 in the mean number of inflammatory acne lesions (70.5% and 86.1% respectively), non-inflammatory acne lesions (81.5% and 92% respectively), and total acne lesion count (75.6 and 88.8% respectively) from baseline. Although 11.9 percent of subjects experienced side effects during treatment with tazarotene, mostly consisting of itching (4.8%), erythema and dryness (2.4%), and burning (1.6%), these events were graded as mild in nature. Because there was no randomization or vehicle control group in this trial, these results must be interpreted cautiously.

Based on the previously discussed trials and our experience, tazarotene appears to be the most effective though most irritating topical retinoid for treating acne in pigmented skins.^30,31 Adapalene 0.1% gel shows the least potential for irritation while still maintaining efficacy comparable to tretinoin 0.025% gel in treating acne in pigmented skins.

Tazarotene is the only topical retinoid FDA-approved for the treatment of mild-to-moderate plaque psoriasis. It is often used in combination with a mid-to-high potency topical corticosteroid or Vitamin D analog to enhance efficacy and tolerability.³²

To the best of our knowledge, only one trial has investigated the use of topical retinoids for psoriasis exclusively in pigmented skins. A 12-week study consisting of 36 East Indian psoriatic subjects compared the clinical efficacy of tazarotene 0.1% cream with clobetasol propionate 0.05% cream in the treatment of chronic plaque psoriasis.³³ While tazarotene was found to be less effective in terms of reducing erythema and scaling, it was determined to be more effective in reducing plaque induration. As expected, the main side effect of tazarotene was mainly mild irritation seen in 19.4 percent of subjects, whereas hypopigmentation and skin atrophy was seen in 19.4 percent and 8.3 percent of subjects in the clobetasol group, respectively.

As demonstrated in the previously mentioned trial, the risk of hypopigmentation is relatively common and more noticeable in pigmented skins when using clobetasol. Extra consideration must be given to quickly find an appropriate steroid-sparing regimen, potentially using tazarotene, in treating psoriasis in this patient population.

Photoaging in darker skinned individuals often becomes apparent at a much later period in life compared to Caucasians.⁷ Topical retinoids are useful in the treatment of photoaging because they partially restore type I pro-collagen formation, which is decreased in photodamaged skin.³⁴ Retinoids counteract the effects of ultraviolet radiation exposure by compacting the stratum corneum, increasing epidermal thickness, eliminating dysplasia and atypia, promoting angiogenesis, increasing granular layer thickness and reducing melanin content.³⁵

There is a paucity of studies looking into the anti-aging properties of retinoids in darker skin types. One particular trial explored the treatment of dyspigmentation, which is the primary manifestation of photoagaing in Far-East Asians. In a 40 week trial consisting of 45 photoaged Chinese and Japanese subjects, once-daily application of 0.1% tretinoin cream significantly lightened hyperpigmented lesions due to photoaging.³⁶ Hyperpigmented lesions in the tretinoin group were lighter or much lighter in 90 percent of subjects as compared with 33 percent in subjects receiving vehicle cream. Erythema or scaling of at least moderate degree occurred in 91 percent of subjects who received tretinoin and in 17 percent of subjects in the vehicle group. This was accompanied by a statistically significant 41 percent reduction in epidermal pigmentation on histologic analysis of lesions treated with tretinoin. The significance of this trial is based on the determination that using topical tretinoin for dyspigmentation, the primary manifestation of photoaging in pigmented skins, can be effectively diminished similarly to fine wrinkling, the primary manifestation of photoaging in Caucasians.

Pseudofolliculitis barbae is a chronic inflammatory disorder that is related to the inherent curvature of the hair follicle in blacks.^37,38 It is rather common, occurring in 83 percent of black army recruits.³⁷ The utility of topical retinoids may involve reducing the hyperkeratosis that results from cyclic piercing of the follicular epithelium.³⁹