Phenoxybenzamine-d 5 (hydrochloride) is the deuterium labeled Phenoxybenzamine hydrochloride. Phenoxybenzamine hydrochloride is a nonselective, irreversible, orally active α-adrenoceptor antagonist that is commonly used for the research of hypertension, specifically caused by pheochromocytoma. Phenoxybenzamine hydrochloride also shows antitumor activity.