Birmingham, Alabama 35294


The purpose of this protocol is test whether patients with hypertension refractory to antihypertensive treatment have evidence of excessive sympathetic (i.e., nervous system) activity.

Study summary:

Refractory hypertension refers to high blood pressure that is failing conventional antihypertensive therapies. In a retrospective assessment of such patients in our clinic we observed that resting clinic heart rates were higher in patients with refractory hypertension compared to patients with controlled hypertension. This observation has led to the hypothesis that refractory hypertension is caused by excessive sympathetic output. This protocol is designed to test this hypothesis by comparing the BP response to carvedilol verses chlorthalidone in patients with refractory hypertension. If their extreme treatment resistance is neurogenic is etiology, a significantly larger BP response to carvedilol should occur compared to chlorthalidone.


Inclusion Criteria: - Uncontrolled clinic BP (>140/90 mmHg) - Receiving 5 or more antihypertensive agents including an ACE inhibitor or ARB, calcium channel blocker, and chlorthalidone 25 mg Exclusion Criteria: - Current use of an alpha or beta or combined alpha-beta antagonist - Known allergy to alpha-beta antagonists - CKD (eGFR <40 ml/min/m2) - MI, stroke or episode of CHF exacerbation within 3 months - Bradycardia <50 bpm; history of 2nd or 3rd degree heart block unless treated by a pacemaker - Pregnant or breast-feeding women - Known hypersensitivity to chlorthalidone or other sulfonamide-derived drugs



Primary Contact:

Principal Investigator
David A. Calhoun, MD
Cardiology Department - University of Alabama at Birmingham

Felice Cook
Phone: 205-934-1400

Backup Contact:


Location Contact:

Birmingham, Alabama 35294
United States

David A. Calhoun, MD
Phone: 205-934-4633

Site Status: Recruiting

Data Source:

Date Processed: March 16, 2018

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