Evaluation of Cumulative Skin-irritation of Six Commercinlly Available Topical Retinoic Acid Preparations

Objective To evaluate the cumulative irritative effect of topical retinoic acid preparations on normal skin. Methods A randomlized,doubled blind,placebo-controlled clinical trial was carried out with7groups for 6 tested preparations.All subjects were patch tested with each preparation for 24 hours on Monday to Thursday,and for 72 hours on Friday.The patch tests were performed for 3 consecutive weeks. Results The minimal cumulative irritative effects were found in Group G treated with 0.1% adapalene gel,with a cumulative irritative index of 0.09±0.11 in 20 days.The cumulative irritative index was significantly lower in Group G than that in Group B treated with 0.1% retinoic acid(Diweishuang®)(0.59±0.24),or in 0.025% retinoic acid(Diweishuang®)(0.41±0.22),or in 0.05% retinoic acid(VITAMIN® Cream)(0.25±0.22). Conclusion Adapalene,the third generation of retinoic acid,is characterized by lower irritative effects in comparison to the first generation of topical retinoic acid agents. Key words: Retinoids; Skin irritancy tests; Administration,cutaneous