3. Women who are pregnant or lactating, or women subjects of childbearing potential who refuse to practice adequate contraception. (oral contraceptives or IUD; double barrier such as diaphragm plus spermicide; vasectomized partner who is sterile prior to the female subject's entry and is the sole sexual partner of that female). Childbearing potential is defined as women who are not surgically sterilized (i.e. have not had a hysterectomy, bilateral oophorectomy [ovariectomy], or bilateral tubal ligation) or post-menopausal (i.e., documented absence of menses for one year prior to entry into the study).