ANTIHYPERTENSIVE EFFECTS OF BETA-BLOCKERS ADMINISTERED ONCE DAILY - 24-HOUR MEASUREMENTS

Whole-day automated ambulatory blood pressure (BP) monitoring was used to assess the duration of the antihypertensive actions of the β-bockers atenolol (50 to 100 mg; n = 20) and acebutolol (400 to 800 mg; n = 19) each given once daily at 9 am. When compared with its pretreatment 24-hour average, atenolol decreased diastolic BP by 10 ± 2 mm Hg (p < 0.01) and systolic BP by 12 ± 2 mm Hg (p < 0.01). Acebutolol decreased the 24-hour diastolic BP by 11 ± 1 mm Hg (p < 0.01) and systolic BP by 13 ± 2 mm Hg (p < 0.01). More specifically, a comparison of the two drugs during the final 6 hours (3 am to 9 am) of the dosing interval showed that the mean decrease in diastolic BP of 10.2 ± 1.5 mm Hg with acebutolol was greater (p < 0.05) than the decrease of 6.2 ± 1.3 mm Hg with atenolol. Moreover, this final 6-hour effect of atenolol was less (p < 0.01) than that observed during the first 18 hours of the day. The late effects of acebutolol did not change significantly from its early effects. The two agents also differed in their though (final 2-hour decrease in diastolic BP) and peak (maximum 2-hour decrease in diastolic BP) effects: for atenolol the peak-to-trough difference was 7.8 ± 3.1 mm Hg (p < 0.05), whereas for acebutolol it was 3.8 ± 4.2 mm Hg (N.S.). This study confirms the efficacy of atenolol and acebutolol. Moreover, acebutolol given once daily maintains its antihypertensive effects throughout the entire 24-hour period, including the important early to midmorning hours. © 1990.