Phenoxybenzamine is an α-1 adrenergic receptor antagonist. Phenoxybenzamine may exert a neuroprotective effect by reducing neuroinflammation after traumatic brain injury.

Phenoxybenzamine hydrochloride (NCI-c01661) is 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.