 However Ketoconazole competitively inhibits CYP17A1, therefore its effectiveness will depend on the concentration of Ketoconazole.The drug abiraterone acetate, permanently disables CYP17A1, once it binds to it.Innocrine Pharmaceutical has a selective CYP17A inhibitor called Seviteronel (VT-464) which does not require co-administration of glucocortoid therapy.