Beta-blocker is a type of drug that plays a major role in the treatment of various heart disorders. Beta-blockers reduce the rate and force of the heartbeat, lower blood pressure, and lessen the workload of the heart. Because of these effects, doctors often prescribe beta-blockers to control high blood pressure and reduce the risk of second heart attacks in some patients. Beta-blockers also help control abnormal heart rhythms and prevent repeated attacks of angina pectoris, chest pains due to inadequate oxygen supply to the heart muscle. In addition to being used for heart disorders, beta-blockers also are prescribed to prevent migraine headaches and to control glaucoma, an eye disease.
Beta-blockers include the drugs propranolol, nadolol, and metoprolol. They work by blocking reception of impulses from the sympathetic nervous system. Stimulation by the sympathetic nervous system prepares the heart and many other body organs for increased activity or for emergency situations. The organs receive impulses from the sympathetic nervous system at special sites called alpha and beta receptors. Beta-blockers interfere with reception at the beta receptor sites.
Beta-blockers may produce insomnia and fatigue, and they can trigger heart failure in persons with a seriously weakened heart. Beta-blockers also can cause problems for people with asthma and for diabetics who use antidiabetes drugs.
