Phentolamine hydrochloride is A nonselective alpha-adrenergic antagonist. It is used in the treatment of hypertension and Name: Phentolamine mesilate, Phentolamine ... , Phentolamine hydrochloride, Phentolamine. A nonselective alpha-adrenergic antagonist. It is used in the treatment of hypertension and hypertensive emergencies, pheochromocytoma, vasospasm ...