- A female is eligible to enter and participate in this study if she is of: • Non-childbearing potential (i.e., women with functioning ovaries who have a current documented tubal ligation, women who had a hysterectomy, women who are post-menopausal, or women who have had both ovaries surgically removed); or • Childbearing potential (i.e., women with functioning ovaries and no documented impairment of oviductal or uterine function that would cause sterility). This category includes women with oligomenorrhea (even severe), women who are perimenopausal, and young women who have begun to menstruate. Women of childbearing potential must have a negative serum pregnancy test at screening, and agree to 1 of the following: a Complete abstinence from intercourse from 2 weeks prior to administration of the first dose of GW572016 until 28 days after the final dose of GW572016; or b Consistent and correct use of 1 of the following acceptable methods of birth control: 1. Male partner who is sterile prior to the female subject's entry into the study and is the sole sexual partner for that female subject; or 2. Implants of levonorgestrel 3. Injectable progestogen 4. Any intrauterine device (IUD) with a documented failure rate of less than 1% per year; or 5. Oral contraceptives (either combined or Progestogen only) 6. Barrier methods including diaphragm or condom with a spermicide