Hydrochlorothiazide with or without amiloride for hypertension in the elderly. A dose-titration study.

The blood pressure response to increasing doses of hydrochlorothiazide with or without amiloride was examined in 130 elderly hypertensive patients. After four weeks of placebo, patients were randomly allocated to increasing doses of hydrochlorothiazide or hydrochlorothiazide with amiloride for 12 weeks using a parallel, double-blind study design. Both hydrochlorothiazide and hydrochlorothiazide with amiloride significantly reduced mean (+/- SEM) baseline supine and standing blood pressure (171 +/- 2/102 +/- 1 and 167 +/- 2/102 +/- 1 mm Hg) to 148 +/- 2/84 +/- 1 and 146 +/- 3/85 +/- 1 mm Hg, respectively, at week 16. Amiloride did not exert any additional antihypertensive effect. Only eight patients required hydrochlorothiazide at 100 mg/d, with the remainder responding to 25 to 50 mg/d. Hydrochlorothiazide decreased mean serum potassium level from 4.3 +/- 0.1 mEq/L (4.3 +/- 0.1 mmol/L) during placebo to 4.0 +/- 0.1 mEq/L (4.0 +/- 0.1 mmol/L) at week 16. Ten patients receiving hydrochlorothiazide developed hypokalemia compared with only two receiving hydrochlorothiazide with amiloride. Relatively low doses of hydrochlorothiazide (25 to 50 mg/d) effectively reduce blood pressure in elderly hypertensive patients. Hypokalemia may occur with hydrochlorothiazide alone but is much less common when hydrochlorothiazide is combined with amiloride.