Abstract: 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