beta-blocker

beta-blocker or beta-adrenergic blocking agent , drug that reduces the symptoms connected with hypertension , cardiac arrhythmias , angina pectoris , migraine headaches, and other disorders related to the sympathetic nervous system . Beta-blockers also are sometimes given after heart attacks to stabilize the heartbeat. Within the sympathetic nervous system, beta-adrenergic receptors are located mainly in the heart, lungs, kidneys, and blood vessels. Beta-blockers compete with the nerve-stimulating hormone epinephrine for these receptor sites and thus interfere with the action of epinephrine, lowering blood pressure and heart rate, stopping arrhythmias, and preventing migraine headaches. Because it is also epinephrine that prepares the body for "fight or flight" in stressful or fearful situations, beta-blockers are sometimes used as antianxiety drugs , especially for stage fright and the like. People taking a beta-blocker must avoid caffeine, alcohol, and salty foods, because the interaction of those substances and the drug can raise the heart rate and blood pressure. Propranolol (Inderal) is a commonly used beta-blocker.

beta-blocker Any of a class of drugs that block impulses to beta nerve receptors in various tissues throughout the body, including the heart, airways, and peripheral arteries. These drugs are mainly prescribed to regulate the heartbeat, reduce blood pressure, and relieve angina. They are also being used in an increasingly wide range of other conditions, including glaucoma, liver disease, thyrotoxicosis, migraine, and anxiety states. Beta-blockers are not suitable for patients with asthma or severe lung disease.

beta blocker (beta-adrenoceptor antagonist) Any of a group of drugs that bind preferentially to beta adrenoceptors and hence block their stimulation by the body's own neurotransmitters, adrenaline and noradrenaline. Beta blockers, such as propranolol, oxprenolol, and sotalol, are used to treat disorders of the cardiovascular system, including high blood pressure (hypertension), angina pectoris, and irregularities of heartbeat (arrhythmias). They are also effective in treating anxiety and glaucoma (as eye drops) and in preventing migraine. They tend to dampen the effects of exercise or stress on heart rate, heart output, and blood pressure, as well as improving the oxygenation of the heart muscles. The release of the enzyme renin from the kidneys is also reduced, leading to an overall fall in arterial blood pressure.