Isotretinoin:

A synthetic retinoid, C20H28O2, that inhibits sebaceous gland secretion of sebum and is used in the treatment of severe forms of acne.

A cis isomer of retinoic acid that is a synthetic derivative of vitamin A, that inhibits sebaceous gland function and keratinization, and that is administered in the treatment of severe inflammatory acne but is contraindicated in pregnancy because of its implication as a cause of birth defects