NCIt definition : The hydrochloride salt form of phenoxybenzamine, a synthetic, dibenzamine alpha-adrenergic
antagonist with antihypertensive and vasodilatory properties. Phenoxybenzamine non-selectively
and irreversibly blocks the postsynaptic alpha-adrenergic receptor in smooth muscle,
thereby preventing vasoconstriction, relieving vasospasms, and decreasing peripheral
resistance. Reflex tachycardia may occur and may be enhanced by blockade of alpha-2
receptors which enhances norepinephrine release. Phenoxybenzamine is reasonably anticipated
to be a human carcinogen.;