- Women of childbearing potential (WCBP) must have a negative serum or urine pregnancy test within 7 days of starting study drug. In addition, sexually active WCBP must agree to use adequate contraceptive methods (tubal ligation; intrauterine device; or barrier contraceptive with spermicide) while on study. Oral, implantable, or injectable contraceptives may be affected by cytochrome P450 interactions, and are therefore not considered effective for this study. WCBP must agree to have pregnancy tests every 4 weeks while on study drug. Male subject agrees to use an acceptable method of contraception for the duration of the study.