• Metabolism: Metabolized mainly by O-demethylation, hydroxylation and conjugation, and excretion is primarily by the biliary route. Route of Elimination: Excretion appears to be primarily by the biliary route.
• Uses/Sources: For the topical treatment of comedo, papular and pustular acne (acne vulgaris) of the face, chest or back.
• Health Effects: Chronic ingestion of the drug may lead to the same side effects as those associated with excessive oral intake of Vitamin A.
• Route of Exposure: Absorption of adapalene through human skin is low. Only trace amounts (<0.25 ng/mL) of parent substance have been found in the plasma of acne patients following chronic topical application of adapalene in controlled clinical trials

• Carcinogenicity: No indication of carcinogenicity to humans (not listed by IARC).
• Toxicity: The acute oral toxicity of adapalene in mice and rats is greater than 10 mL/kg

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.