A modern rationale for the use of phenoxybenzamine in urinary tract disorders and other conditions

Phenoxybenzamine (PBZ) is a nonselective, irreversible alpha-adrenergic receptor antagonist that is approved for the treatment of diaphoresis and hypertension associated with pheochromocytoma. It may also be useful in several chronic conditions whose pathogenesis is mediated or affected by alpha-adrenergic stimulation, such as lower urinary tract symptoms associated with benign prostatic hyperplasia (BPH) and neurogenic bladder (eg, secondary to myelomeningocele and in sphincter dyssynergia and autonomic dysreflexia); in an adjunctive role after urogenital surgery or brachytherapy by relieving symptoms associated with increased alpha-adrenergic tone; and in the treatment of complex regional pain syndrome (CRPS) and prostatitis. However, carcinogenic concerns may have limited its potential application.

The purpose of this article is to reassess the usefulness and contemporary application of PBZ for the control of urinary tract symptoms associated with BPH and neurogenic bladder, after urogenital surgery and brachytherapy, and in certain other conditions (eg, CRPS, prostatitis).

A search of literature published from 1966 to 2002 was performed on MEDLINE using the search terms phenoxybenzamine, alpha-adrenergic blockers, benign prostatic hyperplasia, neurogenic bladder, urinary retention, and complex regional pain

Despite concerns about possible carcinogenicity, no reports of drug-related tumors have been made since PBZ's introduction in 1953. Investigators have used PBZ in off-label trials to alleviate symptoms of a variety of conditions that cause urinary retention. In adult male patients with retention due to inguinal hernioplasty and female patients with retention caused by vaginal repair, as well as in pediatric patients with myelomeningocele, treatment with PBZ improved bladder function and, in the patients with myelomeningocele, was associated with reduced incidence of urinary tract infection. Larger tri- als of PBZ in men with BPH produced significant urinary symptom relief (P < 0.05 in 2 studies). Moreover, studies suggest that PBZ may be useful in alleviating pain due to trauma and CRPS. The most common adverse events appear to be dizziness, impotence and ejaculatory dysfunction, and nasal stuffiness.

No drug-related tumors in humans have been reported after -50 years of clinical experience with PBZ. Clinical trials have demonstrated that it can relieve symptoms in patients with BPH and other urologic and pain-related conditions.