In vitro activity: Adapalene binds to retinoic acid receptors found predominantly in the terminal differentiation zone of epidermis and is more active than tretinoin in modulating cellular differentiation. Adapalene shows greatest affinity for the subtype PARγ, found predominantly in the epidermis. Adapalene is more active than indomethacin, betamethasone valerate, tretinoin, isotretinoin or etretinate in inhibiting lipoxygease activity, but it has little activity against cyclo-oxygenase. Adapalene time- and dose-dependently suppresses DNA synthesis and induces apoptosis in Colon carcinoma cell lines CC-531, HT-29 and LOVO as well as human foreskin fibroblasts. Adapalene shows significantly more effective antiproliferative and proapoptotic effects than 9-cis-retinoic acid (CRA), showing remarkable effects even at 10 μM. Adapalene disrupts DeltaPsi(m) and induces caspase-3 activity in responsive tumor cells.

Cell Assay: Adapalene time- and dose-dependently suppresses DNA synthesis and induces apoptosis in Colon carcinoma cell lines CC-531, HT-29 and LOVO as well as human foreskin fibroblasts. Adapalene shows significantly more effective antiproliferative and proapoptotic effects than 9-cis-retinoic acid (CRA), showing remarkable effects even at 10 μM. Adapalene disrupts DeltaPsi(m) and induces caspase-3 activity in responsive tumor cells.

Drugs. 1997 Mar;53(3):511-9; Exp Dermatol. 2007 Jun;16(6):500-6.