Conditions: High Blood Pressure
Keywords: Nitric Oxide Adrenergic beta-Antagonists Antihypertensive Agents Vasodilator Agents Anti-Arrhythmia Agents Sympatholytics Vascular Resistance Neurotransmitter Agents Cardiovascular Diseases Metoprolol succinate Therapeutic Uses Metoprolol Vascular Diseases Nebivolol Cardiovascular Agents Endothelium-Dependent Relaxing Factors
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 91
Healthy volunteers: no

Brief summary:
High blood pressure (hypertension) is called the "silent killer" because many people do not know they have it, and do not know when it is well controlled. Unfortunately, over time uncontrolled hypertension can cause irreversible organ damage that can lead to heart attack, stroke, heart failure, and kidney failure. If a person cannot control their blood pressure with diet and exercise, doctors often prescribe medications to help control the blood pressure. Nebivolol is a medication that has been recently approved by the FDA for the treatment of hypertension. Our study will investigate whether treatment with nebivolol, as compared to another medication called metoprolol, in African Americans with hypertension will be more effective in protecting blood vessels against the harmful effects of high blood pressure.

Over time high blood pressure causes hardening of the arteries (atherosclerosis) which leads to narrowing of the blood vessels and reduces blood flow to our organs. Arteries also relax and contract naturally, which further changes the blood supply. When arteries are narrowed, exercise can bring on a condition in which the blood supply is inadequate, and this might result in the sensation of pain.

Cells lining our blood vessels produce a variety of substances that normally cause arteries to relax. Two of these substances are called nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF). We are trying to determine the nature of these substances in African Americans with high blood pressure and how it is affected by nebivolol and metoprolol. One way to determine this is to inject drugs such as L-NMMA (N(G)-monomethyl-L-arginine) or TEA (tetraethylammonium chloride), which block the production of NO and EDHF respectively, and then study what happens to the blood flow at rest and during exercise. It is our thought that nebivolol, in comparison to metoprolol, will increase the substances that naturally cause arteries to relax and improve blood supply.

Detailed description:

Arms:
arm 1: Subjects are randomized to Nebivolol 5mg and titrate to Nebivolol 10mg two weeks after drug initiation. Ten weeks after titration subjects will cross over to Metoprolol XL 50mg and titrate to Metoprolol XL 100mg two weeks after cross over. arm 2: Subjects are randomized to Metoprolol XL 50mg and titrate to Metoprolol XL 100mg two weeks after drug initiation. Ten weeks after titration subjects will cross over to Nebivolol 5mg and titrate to Nebivolol 10mg two weeks after cross over.

Interventions: intervention 1: Nebivolol intervention 2: Metoprolol XL
Intervention descriptions: intervention 1: Subjects will be randomized to either nebivolol or metoprolol xl, and remain on the study drug for 10 weeks. They will then "cross over" to take 10 weeks of the comparator drug. intervention 2: Subjects will be randomized to either nebivolol or metoprolol xl, and remain on the study drug for 10 weeks. They will then "cross over" to take 10 weeks of the comparator drug.

Protocol document: