Mechanistically, adapalene binds to specific retinoic acid nuclear receptors (gamma and beta) and retinoid X receptors but does not bind to the cytosolic receptor protein. Although the exact mode of action of adapalene is unknown, it is suggested that topical adapalene may normalize the differentiation of follicular epithelial cells resulting in decreased microcomedone formation.

Adapalene is a chemically stable retinoid-like compound. Biochemical and pharmacological profile studies have demonstrated that adapalene is a modulator of cellular differentiation, keratinization, and inflammatory processes all of which represent important features in the pathology of acne vulgaris.

Metabolized mainly by O-demethylation, hydroxylation and conjugation, and excretion is primarily by the biliary route.

The acute oral toxicity of adapalene in mice and rats is greater than 10 mL/kg. Chronic ingestion of the drug may lead to the same side effects as those associated with excessive oral intake of Vitamin A.

1. Rolewski SL: Clinical review: topical retinoids. Dermatol Nurs. 2003 Oct;15(5):447-50, 459-65. Pubmed