<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A steroidal compound with antiandrogen activity. Abiraterone inhibits the enzymatic activity of steroid 17alpha-monooxygenase (17alpha-hydrolase/C17,20 lyase complex; CYP17A1), 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.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>