Abiraterone is a 3beta-sterol that is androsta-5,16-dien-3beta-ol substituted at position 17 by a 3-pyridyl group. Administered as the O-acetate, it is used for treatment of metastatic castrate-resistant prostate cancer. It has a role as an antineoplastic agent and an EC 1.14.99.9 (steroid 17alpha-monooxygenase) inhibitor. It is a 3beta-sterol, a member of pyridines and a 3beta-hydroxy-Delta(5)-steroid. It derives from a hydride of an androstane.