6. If the patient is female, the patient must not be pregnant or breast-feeding and not planning to become pregnant or to breast-feed for the duration of the study. Women of childbearing potential must commit to using a medically acceptable method of birth control such as oral contraception, intrauterine device (IUD), or a double-barrier method of contraception. Women using oral contraception must have done so for at least 3 months prior to randomization, and continue to do so for the duration of the study. To be considered not of childbearing potential, women must be post-menopausal for at least 2 years or surgically sterile.