i·so·tre·ti·noin 
(ī′sō-trĕtn-oin′)
(ī′sō-trĕtn-oin′)n.
A synthetic isomer of retinoic acid that inhibits sebaceous gland secretion and is used in the treatment of severe nodular acne. It can cause birth defects if taken during pregnancy.
[ISO- + tretinoin, retinoic acid (T(RANS)- + RETINO(IC ACID) + -IN).]