Cumulative irritation potential of adapalene 0.1% cream and gel compared with tazarotene cream 0.05% and 0.1%

Despite the many beneficial effects of dermatologic applications, most of the current treatments for acne cause local irritation. The objective of this study was to compare the ability of the epidermis to tolerate adapalene 0.1% cream and gel and tazarotene cream in concentrations of 0.05% and 0.1%. A total of 30 subjects were enrolled in the study. The test products were applied under occlusive dressings at randomized sites on the upper back for approximately 24 hours, 4 times a week, and for 72 hours, once a week, for a period of 3 weeks. Skin reactions (erythema score plus other local reactions) at the product application sites were assessed 15 to 30 minutes after dressing removal. Twenty-six subjects completed the study. A total of 16 subjects discontinued use of 1 or more of the test products because of irritation scores reaching severe or greater; all but one of these discontinuations were at sites treated with the tazarotene products. The mean 21-day cumulative irritancy indices for adapalene 0.1% cream and gel were significantly lower (P=.05) than those for tazarotene cream 0.05% and 0.1% and not notably higher than that of the negative control product.