The primary objectives of this study are to evaluate the safety, tolerability, efficacy, and pharmacokinetics (PK) of two doses of GSK232802 administered once daily for 12 weeks in healthy menopausal women with moderate to extremely severe Vasomotor Symptoms (VMS). This is a parallel-group, double-blind, randomized, placebo-controlled, active comparator, multicenter study to take place over a 20 week period. The study will evaluate 2 doses of GSK232802, 25 mg and 75 mg as compared to placebo or low-dose estrogen (0.3 mg).

Participants will be randomly assigned to either study drug or placebo for 140 days (20 weeks) divided into 9 visits. Subjects will keep a daily eDiary from visit 3 thru visit 8 to record their VMS symptoms. There will be multiple blood samples and various questionnaires collected.

GSK232802 is a selective estrogen receptor modulator (SERM) that when binding to the estrogen receptor elicits a change similar to estrogen. In preclinical studies it has demonstrated positive effects in preventing bone loss, preventing vaginal atrophy and restoring thermal regulations with minimal stimulation to breast and uterine tissue.