Influence of an angiotensin converting-enzyme inhibitor on diuretic-induced metabolic effects in hypertension.

Diuretic therapy is frequently accompanied by undesirable biochemical changes and side-effects. Two multicenter trials compared the effects of captopril combined with a diuretic to the administration of either agent alone in mild-to-moderate hypertensives. In addition to blood pressure, effects on serum potassium, uric acid, glucose, and cholesterol were examined. The first study (Study A) was conducted on 210 such patients randomly assigned to receive: 1) hydrochlorothiazide (H) 15 mg three times daily (t.i.d.); 2) captopril (C) 25 mg t.i.d.; or 3) C + H for 6 weeks. The second study (Study B) involved 415 patients randomly assigned to receive: 1) C 25 mg twice daily (b.i.d.) + H 25 mg b.i.d.; 2) C 50 mg b.i.d. + H 25 mg b.i.d.; 3) C 50 mg b.i.d. + placebo b.i.d.; 4) placebo b.i.d. + H 25 mg b.i.d.; or 5) placebo b.i.d. + placebo b.i.d. for 6 weeks. In both Studies A and B, all patients except those receiving placebo only (Study B-5) had significant (p less than 0.05) blood pressure reductions. In Study A, the combination of C + H (A-3) produced a significantly greater (p less than 0.001) reduction in blood pressure than either agent alone. In Study B, both C + H groups (B-1, B-2) had a significantly greater (p less than 0.01) blood pressure reduction than that seen with C alone (B-3). In Study A, those treated with H alone (A-1) had a significant (p less than 0.05) reduction in serum potassium and increases in uric acid, glucose, and cholesterol when compared to C alone (A-2) where no changes in these parameters were observed.(ABSTRACT TRUNCATED AT 250 WORDS)