Also called adrenoceptor-blocking agents or alpha blockers, these drugs stop the stimulation by HORMONES with ADRENALINE-like characteristics of alpha-adrenergic receptors at the nerve endings of the SYMPATHETIC NERVOUS SYSTEM. The drugs dilate the arteries, causing a fall in blood pressure, so they are used to treat HYPERTENSION and are also sometimes prescribed to alleviate the symptoms of benign enlargement of the PROSTATE GLAND. Examples of this group of drugs are doxazosin, indoramin, phentolamine and prazosin. The drugs should be used with caution as some may cause a severe drop in blood pressure when first taken.