- All female patients of childbearing potential or less than 1 year postmenopausal must have a negative β-HCG pregnancy test at baseline and practice a medically acceptable method of birth control (i.e., oral contraceptives for at least 3 months, implantation of an intrauterine device for at least 2 months, or barrier methods [e.g., vaginal diaphragm, vaginal sponge, or condom with spermicidal jelly]) during and for 3 months after study initiation