Adapalene, a new chemical entity with retinoid activity.

Adapalene is a novel chemical entity which, in terms of pharmacology, behaves similar to tretinoin, but is chemically and photochemically stable. It has a particular selectivity profile for the known nuclear retinoic acid receptors with low affinity for RAR alpha and no transactivating potential for RXR alpha. This receptor profile could imply that adapalene, in contrast to tretinoin, affects the terminal differentiation pathway of epidermal cells rather than their proliferation. Furthermore, adapalene does not bind to members of the cellular retinoic acid binding protein family. Adapalene has comedolytic activity in the topical rhino mouse model. It exerts a moderate-to-potent anti-inflammatory effect in a series of in vitro and in vivo models. In comparative clinical studies involving 72 acne patients, the efficacy of adapalene was comparable, if not superior, to tretinoin, but adapalene was better tolerated. The data reviewed in this paper indicate that adapalene should be particularly beneficial in the treatment of acne.