[Prazosine: a new vasodilator used for treatment of hypertension (author's transl)].

Prazosine, a derivative of quinazoline, acts by relaxing the smooth vascular muscles and blocking postsynaptic alpha-adrenoreceptors. A special protocol was used to treat arterial hypertension in 21 subjects. A small dose (0.5 mg) was given the first day to avoid orthostatic hypotension, then 0.5 mg x 3 on days 2, 3 and 4, followed by 1 mg x 3 on subsequent days. Dosage can be progressively increased up to 30 mg/day. During the first 36 days of treatment, prazosine was given alone. A significant drop in systolic and diastolic arterial pressure was observed in the reclining subject. The effect on orthostatic pressures were nevertheless significantly lower than before initiating treatment. Prazosine induces only a slight increase plasma renin activity. In 9 patients the use of prazosine alone at 3 to 6 mg per day produced not only a drop in arterial pressure but its normalization. In 5 other patients, the administration of prazosine associated with a beta-blocker, acebutolol, induced normalization of arterial pressure. The association of prazosine with a thiazide diuretic was not considered successful. In 5 patients, treatment was interrupted with the appearance of coronary insufficiency, orthostatic hypotension and frequent headaches. Minor side-effects observed in 8 others patients did not require interruption of treatment. Based on the above results, it can be stated that prazosine is an efficient new peripheral vasodilator with good patient tolerance for the treatment of arterial hypertension.