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.

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.

be·ta block·er • n. any of a class of drugs that prevent the stimulation of the adrenergic receptors responsible for increased cardiac action. Beta blockers are used to control heart rhythm, treat angina, and reduce high blood pressure.

beta blocker n. a drug that prevents stimulation of the beta-adrenergic receptors at the nerve endings of the sympathetic nervous system. Beta blockers decrease the activity of the heart and some reduce the production of aqueous humour (and therefore pressure) inside the eye. They include propranolol, oxprenolol, sotalol, levobunolol, and timolol.