Phenoxybenzamine, a long-acting, adrenergic, alpha-receptor blocking agent, can increase blood flow to skin, mucosae, and abdominal viscera and lower supine and erect blood pressures. The initial dose is 10 mg of Dibenzyline (phenoxybenzamine hydrochloride) bid with increases once daily, usually up to 20-40 mg 2-3 times/days.
McGuire et al. (1976) reported that hypertension, headache and anxiety of AD could no longer be provoked with bladder filling (but sweating continued to occur) in the six subjects who took phenoxybenzamine (dose range from 10 to 20mg) daily. This result is opposite to Lindan et al.’s (1985) findings. They reported that after talking phenoxbenzamine for 4 or more days, blood pressure still rose with bladder distension in ten subjects and remained at the base level in only two subjects.
There is level 4 evidence (from one pre-post study and one case series study) for use of Phenoxybenzamine in the management of AD. However, the results are conflicting with no effects seen in one study (Lindan et al. 1985) and positive effects in another (McGuire et al. 1976).