The effect of the addition of allopurinol on blood pressure control in African Americans treated with a thiazide-like diuretic

We tested the hypothesis that xanthine oxidase inhibition among African Americans receiving the thiazide-type diuretic chlorthalidone may improve blood pressure control with fewer hyperuricemia-related side effects. We performed a randomized, double-blind, placebo-controlled study of African Americans with Stage 1 hypertension without clinically significant renal disease. One hundred fifty African American men or women between the ages of 18 and 65 years who met the exclusion/inclusion criteria with untreated or treated hypertension were started on chlorthalidone (25 mg/d) and potassium chloride. After a 5-week run-in on chlorthalidone, baseline testing was performed and they were randomized to allopurinol (300 mg/dL) or placebo with doses adjusted based on uric acid levels and followed for 8 weeks. One hundred ten subjects completed the study. Baseline systolic blood pressures after the 5-week chlorthalidone run-in were 119.9 +/- 13.6 in the allopurinol group and 117 +/- 11.2 in the placebo group indicating excellent blood pressure control with the single agent. After at least 4 week postrandomization, the difference in mean change in systolic blood pressure in allopurinol less placebo from visits 5 to 3 was 4.3 mm Hg (95% confidence interval, -0.2 to 8.7; P = .059). The difference in mean change in uric acid levels over the same period was 2.1 mg/dL (95% confidence interval, 1.7-2.6; P < .001). The use of chlorthalidone with or without allopurinol resulted in excellent blood pressure control. The addition of allopurinol tended to improve clinic blood pressure, but the difference from the group receiving chlorthalidone alone was not statistically significant. Published by Elsevier Inc. on behalf of American Society of Hypertension.