PHARMACOLOGY — Topical retinoids are often used for first-line treatment of acne, either alone or in combination with a topical antibiotic or topical benzoyl peroxide, which also has antibacterial activity. Adapalene modulates keratinization, inflammation, and differentiation of follicular epithelial cells, decreasing formation of comedones and inflammatory lesions. Retinoid/antimicrobial combinations are more effective than either component alone, particularly in patients with inflammatory acne.1,2

CLINICAL STUDIES — In clinical trials, significantly more patients with acne achieved clear or almost clear skin with adapalene 0.1%/benzoyl peroxide 2.5% than with its individual components alone, with significant differences in total lesion counts detectable within 1 week (median total lesion count decreased by 51% with the combination and by about 35% with adapalene or benzoyl peroxide alone).3

ADVERSE EFFECTS — All retinoids can cause erythema, dryness, scaling, burning, and pruritus, but adapalene is generally better tolerated than other topical retinoids. Pruritus and burning are most severe immediately after application of Differin Epiduo gel; these effects usually decrease over time. Benzoyl peroxide can cause irritation and allergic contact dermatitis. It can also bleach hair and colored fabrics. Retinoids are teratogenic; even though only small amounts of topical retinoids are absorbed systemically, they should not be used during pregnancy.

ADMINISTRATION — Differin Epiduo gel is available in 15-and 45-gram pump bottles. A thin layer of the gel should be applied to affected areas once daily. Patients should minimize exposure to sunlight, use sunscreen, and wear protective clothing.