- For female subjects of childbearing potential: Negative serum pregnancy tests. An efficacious hormonal (i.e., oral, implantable or injectable) or barrier method of birth control must be used at least 1 month before Screening and Month 6 and at least 1 month after Day 28 and Month 6. These subjects will sign an agreement that birth control will be practised during the specified periods and will specify the method used. Female subjects unable to bear children must have this documented (e.g., tubal ligation or hysterectomy).