[A new principle in long-term treatment of essential hypertension: angiotensin-converting enzyme inhibition (author's transl)].

: The blood pressure lowering effect of the orally effective converting-enzyme-inhibitor captopril (SQ 14.225) was investigated in a double-blind study in 20 patients with moderate essential hypertension. During treatment with captopril alone (150 mg t.i.c.) blood pressure dropped from an average of 167/111 to 148/99 mm Hg lying and from 164/113 to 143/99 mm Hg upright whereby 4 patients showed normalisation of their blood pressure (less than 145/95 mm Hg). There was no significant change of pulse frequency. Addition of hydrochlorothiazide led to return to normal of blood pressure in all patients. Even after 6 months of treatment tolerance had not developed. The antihypertensive effect of captopril alone paralleled the one of hydrochlorothiazide and there were no side effects. Activity of the converting enzyme in serum as well as plasma concentrations of angiotensin II and aldosterone were clearly lowered by captopril whereas plasma renin activity increased significantly. Renal sodium and water excretion and glomerular filtration rate were not influenced.