Double-blind, placebo-controlled trial of potassium chloride in the treatment of mild hypertension.

Abstract

Epidemiological and experimental data suggest blood pressure-lowering effects of dietary potassium. A randomized, double-blind clinical trial was used to assess blood pressure response to orally administered potassium, 120 mEq/day, and to placebo in 101 adults with mild hypertension. Blood pressure was measured with a random-zero sphygmomanometer every 2 weeks of this 8-week-trial. Systolic blood pressure in the potassium-treated group decreased by 6.4 .+-. 13.7 (SD) mm Hg (p .ltoreq. 0.025) compared with 0.11 .+-. 13.0 mm Hg in the placebo-treated group (p = 0.96). Diastolic blood pressure in the potassium-treated group decreased by 4.1 .+-. 8.3 mm Hg (p .ltoreq. 0.05) compared with a 1.6 .+-. 6.5 mm Hg decrease in placebo-treated subjects (p = 0.09). Baseline blood pressure of potassium-treated subjects was unexpectedly higher than that of controls. After correcting for baseline variation, blood pressure still decreased 3.4/1.8 mm Hg more in potassium recipients than in placebo recipients (p = 0.14 and 0.24, respectively). Blood pressure decreased by 19/13 mm Hg in five blacks taking potassium versus a 1/0 mm Hg increase in seven blacks taking placebo. Compliance with the potassium regimen was 91.5% by pill count; only one subject discontinued treatment because of side effects. In conclusion, 120 mEq/day of microencapsulated potassium chloride was well tolerated in adults with mild hypertension. An antihypertensive effect of potassium cannot be ruled out despite the fact that there was not statistically significant difference between potassium-treated and placebo-treated subjects after adjustment for differences in baseline blood pressure. Systolic blood pressure was affected more than diastolic blood pressure. Blacks may be particularly sensitive to blood pressure-lowering effects of potassium chloride. A large clinical trial stratified by baseline blood pressure and race is required.