Name: Prazosin (Minipress)
Class: a-Blocking Agent
Mechanism: Blocks a1 receptors in vasculature ® arteriolar & venous vasodilation.
Absorption: Oral. 50% bioavailability
Dist.:
Metabolism.:
Excretion, t½: 3 hr.
Toxicity/S.E.s: 1st dose syncope (1%), dizziness, headaches, weakness.
Utility: Treat periph. vasc. disease (Raynaud’s Disease), hypertension (lowers BP w/o producing sig. tachycardia), pheochromocytoma (phenoxybenz. is best), benign prostatic hyperplasia (relieves obstruction symptoms).
Special Features: Prazosin-type a blockers are the only clinically useful anti-hypertensive a-receptor antagonists. Produces less tachycardia than do direct vasodilators. Readily combined w/other drugs.