1. Are male or female. Sexually active men with partners of childbearing potential must agree to use an acceptable form of contraception as determined by the investigator (eg, oral contraceptives, double-barrier methods, hormonal injectable or implanted contraceptives, tubal ligation, or vasectomy) during participation in the study. Female subjects cannot be pregnant or lactating/breast-feeding and must be surgically sterile, postmenopausal as defined later, or practicing an effective method of birth control as determined by the investigator (eg, oral contraceptives, double-barrier methods, hormonal injectable or implanted contraceptives, tubal ligation, or partner with vasectomy). A woman may be considered postmenopausal if she is at least 50 years or older, has a history of no menses for at least 12 months, and has an follicle stimulating hormone (FSH) level over the upper limit of normal for reproductive aged women.