A Subgroup Analysis to Evaluate the Efficacy and Safety of Adapalene-Benzoyl Peroxide Topical Gel in Black Subjects With Moderate Acne

Acne vulgaris is a common, easily recognized skin condition that affects adolescents and adults in all races and ethnicities. In published single-center and national practice surveys, acne vulgaris was the most common dermatologic disorder observed among black patients in the Unites States, (ie, individuals of African ancestry with Fitzpatrick skin types [FST] IV through VI).^1-3 Overall, it is believed that the pathogenesis of acne is similar in all races and ethnicities, but racial, ethnic, and skin type variations in clinical features, potential exacerbating factors and sequelae of acne vulgaris have been described.^4,5 Acne vulgaris in black skin is frequently associated with postinflammatory hyperpigmentation (PIH), which can be a sequela of the acne itself or a complication of treatment (ie, secondary to irritation).^4,5 PIH results from inflammatory mediators which stimulate melanogenesis - a phenomenon that is more common in darkly pigmented skin types due to greater melanocyte reactivity.^4,5 In acne vulgaris, PIH typically results at sites of clinically inflamed lesions (ie, papules, pustules, cysts); however, it is plausible that subclinical inflammation may also contribute to pigment alterations.^4,5 Due to the heightened potential for PIH in darker skin types, it is important to treat their acne with effective therapies that target and minimize the acne-associated inflammation and the causes thereof. ^4,5 It is also important to keep in mind the tolerability profile of the chosen therapies.^4,5

Adapalene, a synthetic retinoid, and benzoyl peroxide, an effective antimicrobial agent, are currently available at concentrations of 0.1% and 2.5%, respectively, as a fixed dose combination gel (Epiduo^® Gel, Galderma Laboratories, L.P.; adapalene-BPO) for the treatment of acne. Adapalene-BPO targets the primary pathogenic factors of acne: proliferation of Propionibacterium acnes, abnormal keratinocyte differentiation, sebum production and accumulation, and most importantly for this population, inflammation.^6,7 Three multicenter, randomized, double blind, parallel-group, placebo controlled studies involving 3,855 subjects have established the safety and efficacy of adapalene-BPO in the treatment of acne for all skin types.^8,9,10 An analysis of pooled data from these 3 studies evaluated whether subjects with skin of color were more sensitive to irritation from topical acne treatment than other skin types; specifically, if the tolerability of adapalene-BPO gel treatment was different in subjects with FST I through III versus FST IV through VI.¹¹ In that analysis, adapalene-BPO was not associated with a higher incidence of any signs or symptoms of irritation in subjects with higher FST.³ The analysis discussed here was conducted based on data from these 3 studies, to investigate the safety and efficacy of adapalene- BPO in subjects who self-identified their race as black.

The 3 studies included in this analysis had similar objectives and designs. They were multicenter, randomized, double-blind, parallel-group, active and vehicle-controlled studies. The efficacy and safety of the adapalene 0.1%–BPO 2.5% combination