Name: Phenoxybenzamine (Dibenzyline)
Class: a-Blocking Agent
Mechanism: Blocks a-receptors. No effect on b-receptors. Forms irreversible (i.e., covalent) bond w/receptors. Vasc— ¯ BP. Reduces compensatory reflexes (orthostatic hypotens.). Blocks pressor response to symp. (EPI reversal). Myocard.—No direct effect. Reflex tachycard. due to ¯ BP. Eye—Miosis. GI—No effect. CNS—High doses ® stimulation and depression.
Absorption: Oral, but poor bioavailability.
Dist.:
Metabolism.:
Excretion, t½: Effect lasts 3-4 days.
Toxicity/S.E.s: Orthostatic hypotension, tachycardia, inhib. of ejaculation.
Utility: Reduce effects of pheochromocytoma.
Special Features: Discovered at the U. of U.