Nuparp 300 mg Nuparp 300 mg contains rucaparib, a targeted oral medicine used in the treatment of certain cancers, including specific forms of ovarian, fallopian tube, primary peritoneal, and prostate cancer. It works by interfering with PARP enzymes that help cancer cells repair damaged DNA. By preventing effective DNA repair, rucaparib can make it difficult for certain cancer cells to survive and continue growing.