Abiraterone acetate is an FDA approved drug, and is an orally active acetate ester of the steroidal compound abiraterone with antiandrogen activity. Abiraterone acetate was approved by the U.S. Food and Drug Administration (FDA) in April 2011. Abiraterone inhibits the enzymatic activity of steroid 17alpha-monooxygenase (17alpha-hydrolase/C17,20 lyase complex), a member of the cytochrome p450 family that catalyzes the 17alpha-hydroxylation of steroid intermediates involved in testosterone synthesis. Administration of this agent may suppress testosterone production by both the testes and the adrenals to castrate-range levels. FDA Approval this drug in May 2011.