- Pregnancy or active breast-feeding. Female patients of childbearing potential (not postmenopausal for at least 5 years or surgically sterilized) must agree not to become pregnant during the duration of the study. Specifically, they must agree to use an appropriate contraceptive regimen. Acceptable regimens include abstinence, systemic hormones, intrauterine devices and barrier methods, such as cervical caps, male or female condoms, or diaphragms with concomitant intravaginal spermicide. A barrier method must have been used without failure for at least 1 year immediately preceding entry into the study.