A non-steroidal inhibitor of the 17,20-lyase activity of CYP17A1 (IC50s = 48 and 19 nM for the rat and human enzyme, respectively); selective for 17,20-lyase activity over 11-hydroxylase activity and CYP3A4 (IC50s = >1,000 and >10,000 nM, respectively); decreases ACTH-induced production of DHEA, androstenedione, cortisol, and aldosterone in monkey adrenal cells (IC50s = 110, 130, 310, and 4,400 nmol/L, respectively); inhibits DHEA production in NCI-H295R human adrenocortical tumor cells; decreases DHEA, cortisol, and testosterone levels in the plasma of intact cynomolgus monkeys for at least 10 hours following a single oral dose (0.3-10 mg/kg) and continuously during chronic dosing (15 mg/kg twice daily)