Rationale for ACE Inhibition in the Elderly: Treatment of Arterial Hypertension with Enalapril

A randomized, double-blind, placebo-controlled trial was conducted with 32 elderly patients (aged 75-97 years) with uncomplicated essential hypertension, to evaluate the efficacy and tolerance of enalapril, an angiotensin-converting enzyme inhibitor. It was given over an 8-week period in doses from 20 to 40 mg/day and was compared with an identical placebo. Enalapril caused a significant reduction in systolic blood pressure (SBP) and diastolic blood pressure (DBP) by the 2nd week, an effect that persisted through to the 8th week (190 +/- 16/102 +/- 7 to 151 +/- 19/85 +/- 11 mm Hg); 67% of patients had their pressures normalized (less than 160/95 mm Hg). BP was also significantly decreased by the 8th week under placebo (183 +/- 16/101 +/- 9 to 165 +/-21/91 +/- 13 mm Hg), but only 35% of patients attained a normal pressure. Heart rate did not change with treatment. Enalapril caused an increase in plasma renin activity (1.22 +/- 0.08 to 3.66 +/- 2.50 ng/ml/h), whereas aldosterone levels remained unchanged. There was a mild, significant elevation of creatinine level with enalapril but other laboratory parameters, including serum potassium, were unaltered. Two deaths occurred in the enalapril group, but were not considered to be treatment-related. The drug was otherwise well tolerated. Serum enalapril concentration was assessed in 10 patients taking 20 mg/day over an 8-day period. At equilibrium, the level was 22.3 +/- 5.0 ng/l and it correlated both with converting enzyme inhibition and with renal function. Enalapril is shown to be an effective and well-tolerated antihypertensive medication in elderly patients.