Rucaparib (AG014699) hydrochloride is an orally active, potent inhibitor of PARP proteins (PARP-1, PARP-2 and PARP-3) with a K i of 1.4 nM for PARP1. Rucaparib hydrochloride is a modest hexose-6-phosphate dehydrogenase (H6PD) inhibitor. Rucaparib hydrochloride has the potential for castration-resistant prostate cancer (CRPC) research.