Treatment of hypertension with an antihypertensive agent possessing vasodilator activity

Administration of the vasodilator agent, prazosin, in dosages from 3-0 to 7-5 mg per day, significantly reduced diastolic and systolic blood pressure in a group of 14 patients with mild or moderate hypertension. Nine of these patients had a lowering of diastolic blood pressure which was at least 10 mm Hg greater than that caused by placebo. Side effects, chiefly dizziness or lassitude, occurred in over half the patients, but were mild and of short duration and did not necessitate suspension of treatment. The antihypertensive effect of prazosin was similar to that produced by methyldopa or propranolol given in comparable doses. If prazosin and propranolol were given concurrently, blood pressure fell to a level which was significantly lower than that associated with the use of either of these agents alone.