Double-blind study of guanabenz acetate in hypertensive patients.

Twenty-five patients with essential hypertension were given 50 mg of hydrochlorothiazide twice daily. Patients were randomly assigned to one of two treatment groups. The group given 6 mg of guanabenz twice daily as well as hydrochlorothiazide showed a significant decrease in systolic blood pressure in the supine, sitting, and standing positions at months 1, 2, and 3, while the diastolic blood pressure was significantly reduced in all three positions at months 1, 2, 3, and 4. In the group given placebo and hydrochlorothiazide, the mean systolic and diastolic blood pressures were significantly reduced in the standing and sitting positions at month 1 and in the standing, sitting, and supine positions at month 4. When mean systolic and diastolic blood pressures of the two groups were compared, the group treated with guanabenz and hydrochlorothiazide had significantly lower systolic and diastolic blood pressure readings in all three positions at month 2 and significantly lower standing diastolic blood pressure readings at month 3 than did the group treated with placebo and hydrochlorothiazide.