Adrenoceptor Antagonist Drugs

Adrenoceptor Antagonist Drugs

Catecholamines play a role in many physiologic and pathophysi-ologic responses as described. Drugs that block their receptors therefore have important effects, some of which are of great clinical value. These effects vary dramatically according to the drug’s selectivity for α and β receptors.. Blockade of peripheral dopamine receptors is of minor clinical importance at present. In contrast, blockade of central nervous system dop-amine receptors is very important;

For pharmacologic research, α₁- and α₂-adrenoceptor antago-nist drugs have been very useful in the experimental exploration of autonomic nervous system function. In clinical therapeutics, non-selective α antagonists are used in the treatment of pheochromo-cytoma (tumors that secrete catecholamines), and α₁-selective antagonists are used in primary hypertension and benign prostatic hyperplasia. Beta-receptor antagonist drugs are useful in a much wider variety of clinical conditions and are firmly established in the treatment of hypertension, ischemic heart disease, arrhyth-mias, endocrinologic and neurologic disorders, glaucoma, and other conditions.

CASE STUDY

A 46-year-old woman sees her physician because of palpita-tions and headaches. She enjoyed good health until 1 year ago when spells of rapid heartbeat began. These became more severe and were eventually accompanied by throbbing head-aches and drenching sweats. Physical examination revealed a blood pressure of 150/90 mm Hg and heart rate of 88 bpm. During the physical examination, palpation of the abdomen  elicited a sudden and typical episode, with a rise in blood pressure to 210/120 mm Hg, heart rate to 122 bpm, profuse sweating, and facial pallor. This was accompanied by severe headache. What is the likely cause of her episodes? What caused the blood pressure and heart rate to rise so high dur-ing the examination? What treatments might help this patient?