What are actions of phentolamine?

In contrast to phenoxybenzamine, phentolamine produces a competitive block of α1 and α2 receptors. Phentolamine is a reversible, non-selective alpha-adrenergic blocker that induces vasodilation. the drug’s action lasts for approximately 4 hours after a single administration used for the short-term management of pheochromocytoma used locally to prevent dermal necrosis following extravasation of norepinephrine. produces postural hypotension and causes epinephrine reversal. induced reflex cardiac stimulation and tachycardia mediated by the baroreceptor reflex and by blocking the α2 receptors of the cardiac sympathetic nerves. can trigger arrhythmias (Beta1 stimulation) contraindicated in patients with decreased coronary perfusion