Pharmacology and chemistry of adapalene.

Retinoid research in the field of dermatology has been influenced by the clinical success of topical tretinoin and oral isotretinoin in the treatment of acne, and by the discovery of high-affinity binding proteins for retinoic acid mediating its action and interaction with other vitamins and hormones. We sought molecules with an optimal balance between stability, efficacy, and local tolerance for topical acne therapy. In vitro and in vivo bioassay systems were used to test the ability of retinoids to modulate cell proliferation and differentiation. In addition, antiinflammatory properties were assessed. Binding and transactivation assays were used to compare affinities and transcriptional activities of adapalene and tretinoin for the nuclear transcription factors, retinoic acid receptors (RARs). Adapalene is a stable naphthoic acid derivative with potent retinoid pharmacology, controlling cell proliferation and differentiation. In addition it has significant antiinflammatory action. The nuclear gene transcription factors RAR beta and RAR gamma mediate the retinoid activity of adapalene.