Comparison of labetalol and prazosin in hypertensive patients using automated ambulatory monitoring.

The differential effects of prazosin and labetalol on blood pressure and heart rate in the clinic and during daily activity were measured in a double-blind study utilizing automatic ambulatory monitors. One hundred five patients with essential hypertension (sitting diastolic blood pressure equal to 101 mm Hg) were randomly assigned to receive prazosin (n = 52) or labetalol (n = 53). Sixty-eight percent of labetalol-treated patients and 50 percent of prazosin-treated patients achieved blood pressure control during clinic visits (sitting diastolic blood pressure less than 90 mm Hg) and were subsequently monitored for 12 hours of normal daily activities. Ambulatory monitoring revealed labetalol-treated patients to have significantly greater decreases in systolic and diastolic blood pressures during daily activity than prazosin-treated patients. Heart rate and rate-pressure product were significantly reduced in the labetalol group but not in the prazosin group. It is concluded that the potential benefits of dual adrenergic blockade, not readily apparent in the non-stressful clinic environment, become more evident during the course of daily activities.