6. Non-pregnant, non-lactating females of childbearing potential who agree to use medically acceptable forms of birth control (abstinence, hormonal contraceptives, diaphragm with spermicide, condom with spermicide, or intrauterine device) throughout the study or females of non-childbearing potential (surgically sterile [hysterectomy or bilateral tubal ligation] or post-menopausal ≥ 1 year). A negative urine pregnancy test must be confirmed at screening for all female subjects who are not surgically sterile.