Dutasteride is a synthetic 4-azasteroid and aza-steroid that replaces the tert-butyl group with a 2,5-bis(trifluoromethyl)phenyl group. It is a selective inhibitor of both type 1 and type 2 steroid 5α-reductase, an enzyme that converts testosterone to 5α-dihydrotestosterone. Used to treat symptomatic benign prostatic hyperplasia in men with an enlarged prostate, it functions as an EC 1.3.1.22 [3-oxo-5α-steroid 4-dehydrogenase (NADP(+))] inhibitor and an antihyperplasia drug. It is a member of (trifluoromethyl)benzenes and delta-lactams, and derives from a hydride of a 5α-androstane.
