Acute and chronic effects of the angiotensin-converting enzyme inhibitor captopril in severe hypertension

Abstract

In this study the acute and chronic effect of the converting enzyme inhibitor captopril was investigated in a relatively large number of patients (acute: n = 78, chronic: n = 67) with various forms of severe hypertension, the majority of cases being resistant to a standardized triple therapy (100 mg of hydrochlorothiazide or 80 to 500 mg of furosemide, 320 mg of propranolol and 200 mg of hydralazine). Up to an observed period of 240 minutes, a single oral dose of 25 mg of captopril led to a significant and marked decrease in systolic and diastolic blood pressure. The acute antihypertensive effect of captopril was more pronounced in patients with renovascular than in those with essential or renal parenchymal hypertension. Similar differences among the three groups of patients were also observed during chronic treatment. Over a period of 18 months, patients with renovascular hypertension showed both a more pronounced decrease in mean diastolic blood pressure values and a significantly higher percentage of cases with excellent blood pressure control (diastolic blood pressure 95 mm Hg or less). Under long-term conditions, about 90 percent of all patients required a diuretic and a substantial percentage also needed propranolol as a third drug. Positive correlations between pretreatment plasma renin activity levels and captopril-induced blood pressure reduction were found under acute conditions only. The most frequent side effects were skin manifestations, taste disturbances, dizziness and unproductive cough. Serious adverse effects were rare and included one case of leukopenia and one of the nephrotic syndrome, both being reversible after withdrawal of captopril. Our results demonstrate that captopril is a very potent blood pressure lowering agent in severe hypertension especially in cases of renovascular hypertension. However, currently the potential risk of serious side effects should induce the physician to reserve this drug for those patients with truly resistant hypertension.