Comparative Effects of Nebivolol and Metoprolol on Female Sexual Function

Beta-blockers (BB) are an important treatment for high blood pressure and heart disease. However beta-blockers can cause sexual dysfunction (SD) and this common side effect limits successful use of this class of medications. Sexual side effects often result in drug discontinuation, compromising therapy goals. The investigators are conducting the study to determine if nebivolol, a newer beta blocker that is selective for receptors in the heart and causes vasodilation in the body causes fewer sexual side effects, or even improves sexual function, compared with metoprolol succinate.

This protocol is designed to compare the effects two beta blockers, nebivolol (Bystolic) 5-10 mg daily with metoprolol succinate (Toprol XL) 100-200 mg daily on sexual function in post-menopausal women with high blood pressure. The study is composed of 2 treatment phases. At baseline subjects are randomized to either nebivolol 5 mg once daily or metoprolol succinate 100 mg once daily. After randomization, subjects are treated for 12 weeks with double blind therapy. Following double-blind therapy subjects enter a 2-week washout phase and are subsequently switched to the alternate therapy.

After 4 weeks (visits 3 and 7) of double-blind treatment with either nebivolol 5 mg once daily or metoprolol succinate 100 mg once daily subjects will be evaluated and the need for dosage titration assessed. If blood pressure is not at goal the dosage of study medication will be doubled to nebivolol 10 mg once daily or metoprolol succinate 200 mg once daily. If blood pressure remains uncontrolled after 8 weeks of double blind treatment with study medication open label amlodipine 5 mg will be initiated (visits 4 and 8) at the discretion of the principal investigator. During double blind treatment subjects will be evaluated in clinic every 4 weeks.

The primary efficacy variable is the change from baseline in Changes in Sexual Functioning Questionnaire (CSFQ) and the Female Sexual Function Index (FSFI).

The primary study objective is to determine whether nebivolol causes fewer sexual side effects compared with metoprolol succinate and if nebivolol improves FSF in women. FSF will be assessed with the above questionnaires-FSFI and CSFQ.

Eligibility Criteria:
Inclusion Criteria:

1. Over the age of 40 years
2. Postmenopausal (according to self report of 12 consecutive months of amenorrhea, serum FSH concentrations greater than 40 international units/L, or surgical history consistent with menopause)
3. In a stable monogamous relationship with a male partner for at least 6 months
4. History of hypertension, treated or untreated
5. Requirement for the initiation of an anti-hypertensive agent OR addition of another anti-hypertensive medication (according to the principal investigator and based on clinical judgment) OR patients requiring monotherapy with an anti-hypertensive that wish to participate in the study and are willing to undergo a two week wash-out of current anti-hypertensive therapy
6. Provide written informed consent prior to participation.

Exclusion Criteria:

1. Properly measured clinic SBP \> 170 mmHg
2. Advanced AV block
3. Severe hepatic disease
4. Heart rate \< 55 beats/min (and not currently on beta blocker therapy)
5. Pregnancy or lactation
6. Heart failure with ejection fraction less than 0.40
7. History of myocardial infarction
8. History of Raynaud's syndrome
9. Patients with alcoholism or recreational drug use will be excluded due to concerns about the ability to comply with the study requirements.
10. Major psychiatric disorder not well controlled with treatment
11. Spinal cord injury
12. Severe respiratory disease, which in the opinion of the investigator contraindicates BB treatment
13. Poorly controlled diabetes mellitus (≥ 9%)
14. Persistent arrhythmia