Effect of guanabenz and hydrochlorothiazide on blood pressure and plasma renin activity.

Patients with mild to moderate essential hypertension were treated with guanabenz plus placebo (26 patients) or guanabenz plus hydrochlorothiazide (26 patients) for one year. Ambulatory plasma renin activity was determined during placebo treatment, after four weeks and one year of treatment with the study drugs, and one month after discontinuation of guanabenz while continuing the same hydrochlorothiazide dosage. Treatment with guanabenz plus hydrochlorothiazide proved more satisfactory than treatment with guanabenz plus placebo in that fewer patients were treatment failures, a smaller dosage of guanabenz was required, better control of supine blood pressure was achieved, and no increase in guanabenz dosage was needed to maintain chronic blood pressure control. Drowsiness, dry mouth, and dizziness were the side effects noted most commonly. Plasma renin activity was not significantly suppressed by chronic guanabenz therapy. Thus, guanabenz is an effective new antihypertensive that provides optimal blood pressure control when used with a diuretic.