Dose-ranging study to delineate the additive antihypertensive effect of guanabenz and captopril.

This open crossover study in eight hypertensive patients defined a possible additive effect of oral guanabenz and captopril and determined a safe and effective dose range. Each group of four patients received placebo followed by ascending doses (on alternate days) of either guanabenz (2, 4, 8 mg) or captopril (6.25, 12.5, 25 mg) as initial monotherapy and were subsequently crossed over to the alternate monotherapy. Guanabenz and captopril were given concomitantly in increasing doses--the highest dose for both groups being 8 mg guanabenz/25 mg captopril. When guanabenz and captopril were given concomitantly, blood pressure decreased, both from the values during placebo administration and from the lead-in values recorded before each dose. Mean supine systolic and diastolic blood pressures after combination therapy decreased significantly (P less than .05) in a dose-related manner at most evaluations. The authors conclude that guanabenz and captopril have an additive effect when administered in combination to patients with hypertension.