Age and the pharmacodynamics of angiotensin converting enzyme inhibitors enalapril and enalaprilat.

The effect of age on the pharmacodynamic responses to converting enzyme inhibitors, enalapril and enalaprilat was investigated in nine young (22-30 years) and nine sex-matched elderly (65-73 years), healthy volunteers. The groups differed in baseline blood pressure, young 121/64 mmHg, elderly 142/75 mmHg (P less than 0.01), but not in sodium intake or body weight. Both enalapril and enalprilat produced significant falls in blood pressure in both groups but no increase in heart rate in the supine or erect posture. The blood pressure fall was significantly greater in the elderly on both treatments and in both erect and supine posture. The greater fall in blood pressure in the elderly was associated with a more prolonged inhibition of plasma angiotensin converting enzyme activity. The apparent age-related difference in response appears to be due to the difference in baseline blood pressures between the groups. Further study of the usefulness of chronic dosing with angiotensin converting enzyme inhibitors in hypertension in the elderly is indicated.