isotretinoin
n. an analog of vitamin A used in the treatment of severe acne that is resistant to other therapies. It is highly teratogenic (see teratogen) and therefore should not be used in pregnancy. More controversially, the use of isotretinoin has been linked with psychological disturbances, such as depression, psychosis, and suicide. The mechanism responsible for these side effects is unknown. U.S. trade name (among others): Accutane.