an alpha-adrenoreceptor blocking agent with direct function on heart and smooth muscle. It is a potent vasodilator utilized in control of extremely high blood pressure correlated with catecholamine excess, as in people with pheochromocytomas. It isn't used often in a clinical environment. American brand name: Regitine.
PHENTOLAMINE: "The doctor has prescribed Phentolamine to treat Mary Ann's malignant hypertension."