4. Female subjects must have negative urine pregnancy tests and must not be lactating prior to receiving study medication and radiation exposure. For females able to bear children, a hormonal (i.e., oral, implantable, or injectable) and single-barrier method, or a double-barrier method of birth control must be used throughout the study. Female subjects unable to bear children must have this documented in the medical record [i.e., tubal ligation, hysterectomy, or post-menopausal (defined as a minimum of one year since the last menstrual period)].