Comparison of prazosin with hydralazine in patients receiving hydrochlorothiazide. A randomized, double-blind clinical trial.

The antihypertensive efficacy and the incidence of side effects of prazosin and hydralazine were compared in a randomized, double-blind trial in 232 adult male hypertensives who could not be controlled with hydrochlorothiazide alone. There were no significant differences between regimens in the percentage of patients who attained goal blood pressure (reduction of diastolic blood pressure to below 90 mm Hg and at least 5 mm less than the baseline randomization pressure), effect on pulse rate or the incidence or reasons for terminations. Absolute reduction of blood pressure was similar for both drugs except for sitting systolic pressure at 3 and 6 months, when prazosin effected a 3.7- and 3.6-mm Hg greater response (p less than 0.05). Orthostatic dizziness (p less than 0.005), sexual dysfunction (p less than 0.02), and nightmares (p less than 0.02) were more frequent with prazosin than with hydralazine; nevertheless, patient compliance was similar for both drugs. An unexpected finding was the lack of pulse rate increase associated with hydralazine, particularly in older patients.