Captopril in the long-term treatment of essential hypertension: changes in the renin-angiotensin-aldosterone system.

We investigated changes in the renin-angiotensin-aldosterone system in seven patients with essential hypertension during treatment with captopril (SQ 14225) (300 to 450 mg/day) for 12 months. While blood pressure decreased, the plasma-renin concentration increased to 700 percent of the initial value (6.1 +/- 2.5 ng angiotensin l/ml . h) and angiotensin I increased to about 300 percent of the basal value (179 +/- 32 pg/ml). Converting enzyme inhibition resulted in a 30 percent decrease in plasma angiotension II levels from a basal level of 66 +/- 21 pg/ml. Plasma aldosterone decreased 52 percent from 63 +/- 13 pg/ml initially. These changes in hormone levels were maintained throughout the study. There was no significant change in serum sodium and serum potassium concentration.