Coreg CR, Blood Vessel Stiffness and Blood Vessel Function

State University of New York - Downstate Medical Center

Status and phase: Unknown; Phase 4

Conditions: Endothelial Function; Hypertension; Diabetes Mellitus

Treatments: Drug: carvedilol; Drug: metoprolol extended release

Study type: Interventional

Funder types: Other

Identifiers

NCT00732511

Glaxo Smith Kline 111105

Details and patient eligibility

About

We are comparing the blood pressure-lowering effects of two marketed medications, Coreg CR and Toprol XL. Although both drugs reduce blood pressure by blocking the action of noradrenaline on beta-receptors in the blood vessels, Coreg CR also blocks alpha-receptors, which may provide added blood pressure-lowering. In addition, Coreg CR may have anti-oxidant actions. Cells which line blood vessels (termed "endothelial cells") make nitric oxide (NO), which relaxes the muscle cells encircling the blood vessels, causing a reduction in blood pressure. When body cells use oxygen, they normally produce "free radicals", which can destroy NO,leading to high blood pressure, heart damage and worsenimg of diabetes. Antioxidants remove free radicals and prevent or repair this damage. In this study we will measure endothelial cell function, blood vessel wall stiffness, NO in exhaled breath, and blood levels of substances which reflect NO production and destruction to determine if a pure beta-blocker (Toprol XL) differs from an alpha/beta blocker (Coreg CR) in these effects. We will also examine the mechanism by which such differences might occur.

Full description

The following techniques will be used:

Endothelial function will be measured non-invasively by flow-mediated changes in pulsatile blood volume in the finger-tips.

Vascular compliance (stiffness) will be assessed by tonometry of the radial pulse wave ("augmentation index") and diastolic puse wave analysis.

Plasma nitrate/nitrite levels mirror NO production and will be measured spectrophotometrically by the Griess reaction.

Plasma nitrotyrosine, an in vivo marker of NO-dependent damage induced by reactive nitrogen intermediates derived from NO, will be measured by ELISA.

Exhaled NO may provide an real-time measure of endothelial cell NO production and can be measured by a hand-held device which contains an electrochemical detector sensitive to 5 ppb.

Enrollment: 40 estimated patients

Sex: All

Ages: 18 to 80 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

1. Type 2 diabetes mellitus,
2. Stable antidiabetic regimen for 3 months
3. Hemoglobin A1c <8.6%
4. Stable antihypertensive medication regimen for 3 months or more, including either an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker

Exclusion criteria

1. Any clinically significant abnormality on history, physical examination, or laboratory testing which could preclude safe completion of the study
2. Significant cardiac conditions
3. Lung disease
4. Cigarette smoking
5. Chronic kidney disease (Stage 3 or greater)
6. Type 1 diabetes
7. Known contraindication to alpha- or beta-blocker therapy

Trial design

40 participants in 2 patient groups

1

Experimental group

Description:

Coreg Cr will be up-titrated as needed to achieve blood pressure \<130/80

Treatment:

Drug: carvedilol

2

Active Comparator group

Description:

Toprol XL will be up-titrated at weekly intervals to achieve a blood pressure \<130/80 mm Hg

Treatment:

Drug: metoprolol extended release