Ambulatory blood pressure and heart rate during once-daily, randomized, crossover administration of carteolol and atenolol

This study evaluated the effect of beta-adrenoceptor blocking agents (beta-blockers) with or without intrinsic sympathomimetic activity on the 24-hour blood pressure profile of 15 untreated patients with essential hypertension. After a 4-week run-in period, subjects were randomly assigned to an 8-week treatment period of once-daily carteolol (15 mg/d) or atenolol (50 mg/d). The groups were crossed over at week 8. Office blood pressure and heart rate were recorded every 2 weeks and 24-hour ambulatory blood pressure monitoring was performed immediately preceding and at the conclusion of each period. Both drugs significantly reduced (P0.01) office blood pressure and heart rate throughout the two treatment periods. The 24-hour ambulatory blood pressure monitoring at 0.5- and 1-hour intervals revealed that systolic blood pressure in 2 of 8 sleeping hours and diastolic blood pressure in 4 of 8 sleeping hours were significantly higher (P0.05) after carteolol treatment than after atenolol treatment. The average values for both daytime and nighttime blood pressures, however, were significantly lower at the end of both periods. Although atenolol lowered heart rate throughout the 24-hour period, there was a smaller reduction in heart rate with carteolol than with atenolol during daytime (-5.4 +/- 4.9 beats/min vs -12.7 +/- 6.6 beats/min, P0.005, respectively). Heart rate increased during nighttime (P0.02) and was significantly greater than with atenolol treatment (5.0 +/- 7.2 beats/min vs -5.7 +/- 8.0 beats/min, P0.001, respectively). These results suggest that the different effects of the two beta-blockers on heart rate and nighttime blood pressure may be attributed to the presence or absence of intrinsic sympathomimetic activity.