Long-term effects of captopril in hypertension

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Abstract
Captopril was given for treatment of hypertension alone or in combination with diuretics to 32 patients for 1-4 mo. periods. The decrement of mean blood pressure after 1 and 2 mo. correlated with pretreatment plasma renin activity (PRA) and the response of blood pressure to infusion of an angiotensin II antagonist. These correlations were no longer apparent after 4 mo. of treatment. When subjects with a decrement of mean blood pressure that exceeded 13 mm Hg were compared with nonresponders, responders not only had higher control PRA and higher PRA at 1 mo. of treatment, but had decreased plasma aldosterone levels, decreased urinary aldosterone excretion and increased serum K levels that persisted over the 4 mo. of observation. The reduction of plasma aldosterone correlated with the fall of mean blood pressure. Urinary kallikrein, catecholamines, electrolytes and endogenous creatinine clearance did not change in response to treatment. The antihypertensive activity of captopril on longt term administration probably depends in part on the blockade of angiotensin II, but other mechanisms cannot be excluded.