- Female subjects of childbearing potential must test negative for pregnancy at screening visit and agree to use the double-barrier method, as defined by 2 physical barriers such as a condom, diaphragm, or cervical occlusive cap, coupled with an additional barrier such as spermicidal foam, gel, film, cream or suppository for the duration of the study. Subjects having undergone a hysterectomy or bilateral oophorectomy or other form of female sterilization or patients having been medically confirmed to be post-menopausal, would not require any other method of contraception.