Prazosin: preliminary report and comparative studies with other antihypertensive agents.

In a group of 14 hypertensive patients a 10-week course of treatment with prazosin 3-7.5 mg/day produced a significant reduction in mean blood pressure without serious side effects. The fall in diastolic pressure exceeded the response to a placebo by 10 mm Hg or more in 9 patients. The average decrease in diastolic pressure was similar to that produced by methyldopa 750 mg/day or propranolol 120-160 mg/day but the fall in systolic pressure was comparatively smaller, consistent with reported experimental work showing that the drug causes vasodilatation. The hypotensive effect of prazosin 1.5-3 mg/day combined with propranolol was significantly greater than that of propranolol alone and resulted in good control of blood pressure.