Comparison of enalapril and propranolol in essential hypertension

In 40 patients with essential hypertension, enalapril was compared with propranolol as an antihypertensive agent in a double-blind study. The patients were randomly given either enalapril 5-10-20 mg bid or propranolol 40-80-120 mg bid in a treatment consisting of step-by-step increases in dosage. When the diastolic blood pressure remained greater than 90 mm Hg on the highest dosage, hydrochlorothiazide was added. Both enalapril and propranolol reduced blood pressure, although the patients tended to achieve lower blood pressures while on enalapril. More patients on propranolol required additional diuretic therapy than patients on enalapril. Propranolol reduced heart rate; with enalapril there were no changes in heart rate. Both drugs increased serum potassium and urea. Plasma renin substrate was reduced by enalapril, but raised by propranolol. Enalapril increased plasma renin activity and angiotensin I, while propranolol reduced both. Converting enzyme activity was lowered with enalapril but was unchanged with propranolol. Both drugs reduced angiotensin II. Plasma aldosterone concentration was more suppressed with propranolol than with enalapril.