The objective of this study is to determine the safety and effectiveness of 3 asoprisnil doses when administered to postmenopausal women with Premarin® 0.625 mg.

The objective of this study is to determine the safety and effectiveness of asoprisnil 5, 10, and 25 mg, compared to placebo, when administered to postmenopausal women, with Premarin® 0.625 mg, for 12 weeks. Pharmacodynamic effects to be assessed include bleeding pattern, endometrial biopsy results, and endometrial thickness. Safety assessments will include clinical laboratory results, physical examination with vital signs, pelvic and breast examinations, ultrasound results, and adverse events

Inclusion Criteria:

• Postmenopausal women with an intact uterus
• Body mass index (BMI) between 18.0 - 33.0
• Good general health
• Endometrial thickness ≤ 4 mm by TVU
• No history or suspected endometrial hyperplasia
• Negative urine pregnancy test
• Pap smear in last 6 months with no evidence of malignancy or pre-malignant changes
• Mammogram without suspicion of malignancy within last 6 months
• Endometrial biopsy with no evidence of pathologic changes within last 6 months

Exclusion Criteria:

• Any abnormal lab result the study-doctor considers significant
• History of severe reaction to hormone therapy
• Receiving hormone therapy
• Currently using phytoestrogenic compounds, such as red clover, black cohosh (Promensil and Remifemin), dong quai, ginseng and soy isoflavones
• History or known or suspected cancer other than basal cell carcinoma
• Stenosis of the cervix
• History of reproductive endocrine disorder
• Washout requirement for hormonal therapy not met
• Ovarian mass
• Submucus or other symptomatic fibroid which would confound efficacy