- Women may be enrolled if they are not pregnant (negative serum βHCG at the Screening Visit), are not breast-feeding, and do not plan to become pregnant during the trial. In addition, they must either have had a hysterectomy or tubal ligation at least 6 months before signing informed consent, be post-menopausal for 1 year, or practicing an acceptable method of birth control. An acceptable method of birth control may be oral, injectable or implantable hormonal contraceptives, intrauterine device, diaphragm plus spermicide, or female condom plus spermicide. Abstinence, partner's use of condoms, and partner's vasectomy are NOT acceptable methods of contraception