4. Female patients of childbearing potential must have negative pregnancy test within 7 days before initiation of study drug dosing. Postmenopausal women must be amenorrheic for at least 12 months to be considered of non-childbearing potential. Surgical sterilization is considered non-childbearing potential. Female patients of reproductive potential must agree to employ an effective method of birth control (hormonal or barrier) throughout the study and for up to 3 months following discontinuation of study drug.