Metoprolol minimizes nighttime blood pressure dip in hypertensive black males.

Twelve hypertensive black males completed the study, which was conducted to evaluate the effect of metoprolol on 24-h ambulatory blood pressure (ABP). Study participants took 50 mg to 100 mg metoprolol twice daily for a minimum of 3 weeks. Metoprolol had no significant effect on blood pressure (147/90 +/- 11/8 mm Hg v 151/88 +/- 16/8 mm Hg, baseline v treated, respectively) in spite of causing significant reductions in heart rate (87 +/- 9 beats/min v 69 +/- 7 beats/min, P < .001). Only one subject had a > or = 10 mm Hg decrease in 24-h diastolic blood pressure. The nighttime fall in blood pressure was minimized by metoprolol and clinically significant increases in daytime or nighttime blood pressure were noted in 58% of patients. Metoprolol therapy failed to lower blood pressure and eliminated the normal nighttime decline in blood pressure. Since the nighttime decline in blood pressure is thought to protect against target organ damage, it may be important to identify antihypertensive agents which preserve or enhance the nighttime blood pressure dip.