This study compares the effects of two common hormone medications on the heart and blood vessels of healthy post-menopausal women over the age of 45.

The study will take place over the course of about 5 months. Each subject will take two different medications over two six-week periods. They will be randomized at the beginning of the study to either estradiol+medroxyprogesterone acetate or estradiol+drospirenone for the first period, and will receive the other medication the second six-weeks of the study. At the very beginning of the study and at the end of each six-week treatment period, subjects will come to the hospital various tests including non-invasive blood vessel imaging tests, blood draws to test the levels of certain hormones in the body, an oral glucose tolerance test, a test to monitor renal blood flow, and 24-hour blood pressure monitoring. Between treatment periods, there will be a four-week medication-free washout period.

Inclusion Criteria:

1. Healthy female postmenopausal volunteers, as defined by absence of menses for at least 12 months and follicle stimulating hormone (FSH) 30 IU/L;
2. Age 45 to 75 years;
3. Systolic blood pressure <140 and >90 mmHg and diastolic blood pressure <90 and >60 mmHg at the screening visit;
4. No personal history of diabetes;
5. Body mass index < 30 kg/m2;
6. No clinically significant abnormalities on screening tests (complete blood count, serum electrolytes, liver enzymes, thyroid stimulating hormone, urinalysis, and electrocardiogram).

Exclusion Criteria:

1. Current smoking, defined as smoking within the 12 months before the screening visit;
2. Alcohol intake >1 beverage per night or history of alcohol abuse;
3. Current or past recreational drug use;
4. Personal history of hypertension, cardiovascular disease (coronary artery disease, congestive heart failure, valvular heart disease, stroke, transient ischemic attack, or intermittent claudication), hyperlipidemia, diabetes (defined as a fasting glucose ≥126 mg/dL), kidney disease, liver disease, venous or arterial thromboembolic disease, adrenal insufficiency, depression, or illness requiring overnight hospitalization in the past 6 months;
5. Risk factors for arterial or venous thromboembolism;
6. Personal history of breast cancer or any other type of cancer;
7. Personal history of endometrial hyperplasia, endometrial cancer, or unexplained vaginal bleeding;
8. History of cervical cancer or abnormal pap smear
9. Prescription or herbal medication use, excluding thyroid hormone supplementation;
10. Ischemic changes on resting electrocardiogram;
11. Serum creatinine ≥ 1.3 mg/dL.
12. Serum potassium level > 5.0 mmol/L;
13. Known hypersensitivity to any of the study drugs;
14. Other active medical problems detected by examination or laboratory testing, except for treated hypothyroidism.
15. Pregnancy

There may have been an order effect of E+DRSP on FMD. For this, however, we would expect %FMD to be lower in the 2nd treatment period, regardless of specific treatment. It is unclear whether this was true cross-over effect or due to the study size.