Adapalene 0.1% and benzoyl peroxide 2.5% as a fixed-dose combination gel is as well tolerated as the individual components alone in terms of cumulative irritancy.

International guidelines recommend the combination of retinoids (e.g. adapalene, tazarotene) and benzoyl peroxide for treating acne because of their complementary mechanisms of action. A new fixed-dose combination gel of adapalene 0.1% and benzoyl peroxide (BPO) 2.5% (adapalene/BPO*) is an effective acne treatment and offers the advantage of a once daily application. This paper reports the results of a cumulative irritancy study in healthy volunteers comparing adapalene/BPO to adapalene 0.1% and BPO 2.5% applied separately, BPO 10% gel, tazarotene 0.1% gel and the gel vehicle as a control.There was no significant difference between the mean cumulative irritation index (MCII) for adapalene/BPO and any test product except tazarotene 0.1% gel, which had a significantly greater MCII than all other test products (p < 0.05). This study showed that adapalene/BPO as a fixed-dose combination is as well tolerated as BPO 2.5% gel alone or adapalene 0.1% gel alone in terms of cumulative irritancy.*Epiduo, Galderma S.A.