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 t he 24-hour blood pressure profile of 15 untreated patients with essent ial 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. Off ice blood pressure and heart rate were recorded every 2 weeks and 24-h our ambulatory blood pressure monitoring was performed immediately pre ceding and at the conclusion of each period. Both drugs significantly reduced (P < 0.01) office blood pressure and heart rate throughout the two treatment periods. The 24-hour ambulatory blood pressure monitori ng 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 sleepi ng hours were significantly higher (P < 0.05) after carteolol treatmen t than after atenolol treatment. The average values for both daytime a nd 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 c arteolol than with atenolol during daytime (-5.4 +/- 4.9 beats/min vs -12.7 +/- 6.6 beats/min, P < 0.005, respectively). Heart rate increase d during nighttime (P < 0.02) and was significantly greater than with atenolol treatment (5.0 +/- 7.2 beats/min vs -5.7 +/- 8.0 beats/min, P < 0.001, respectively). These results suggest that the different effe cts of the two beta-blockers on heart rate and nighttime blood pressur e may be attributed to the presence or absence of intrinsic sympathomi metic activity.