Resting and Exercise Blood Pressure with Atenolol, Enalapril and a Low-Dose Combination

This study was designed to assess the efficacy of 100 mg atenolol daily, 20 mg enalapril daily and a low-dose combination of 50 mg atenolol and 10 mg enalapril, in reducing blood pressure at rest and during ergometry (50-100 W). Twenty-three men and three women (aged 25-56 years, mean 44.5 +/- 7.4 years) were admitted to this randomized, single (observer)-blind crossover study, which had a 2-week placebo period and 4-week treatment periods. Both atenolol and enalapril provided significant (P less than 0.001) and almost identical reductions in blood pressure at rest. However, during exercise, systolic blood pressure decreased with atenolol and with the combination of atenolol and enalapril by 15.8% and 18.4%, respectively, compared with 6.2% with enalapril monotherapy. The differential effect of atenolol and enalapril was also demonstrated for the rate-pressure product. Twenty-four hours after the last dose, systolic and diastolic blood pressures were significantly lower (P less than 0.01) with atenolol (139.5/92.8 +/- 17/12 mmHg) than with enalapril (146.8/97.7 +/- 17/9 mmHg). It is concluded that atenolol is significantly more effective in reducing systolic blood pressure during exercise than enalapril, and that the addition of atenolol to enalapril therapy produces a significant supplementary antihypertensive effect.