Phenoxybenzamine

General information

Phenoxybenzamine is a non-selective irreversible alpha-adrenoceptor antagonist. It is given orally in total daily doses up to 60 mg for management of pheochromocytoma, and lower doses have been used to relieve bladder obstruction before surgery. The maximum effect may be delayed because of irregular absorption, and even after intravenous use it may not be attained for 1 hour. Some of the most severe reactions, that is hypotension and syncope with tachycardia, can therefore occur unexpectedly. In a review of published reports from 1966 to 2002 phenoxybenzamine improved bladder function in adult men with retention due to inguinal hernioplasty, in women with retention caused by vaginal repair, and in children with myelomeningocele, in whom there was also a reduced incidence of urinary tract infections [ ]. The most common adverse events were dizziness, impotence and ejaculatory dysfunction, and nasal stuffiness. No drug-related tumors were reported. Phenoxybenzamine can also cause miosis, lassitude, and gastrointestinal upsets.

Organs and systems