Blocker, beta adrenergic: A class of drugs, also more simply called beta blockers, that block beta-adrenergic substances such as adrenaline (epinephrine), a key agent in the “sympathetic” portion of the autonomic (involuntary) nervous system.
By blocking the action of the sympathetic nervous system on the heart, these agents relieve stress on the heart. They slow the heart beat, lessen the force with which the heart muscle contracts and reduce blood vessel contraction in the heart, brain, and throughout the body.
Beta blockers can serve to treat abnormal heart rhythms (cardiac arrhythmias). They are used specifically to prevent abnormally fast heart rates (tachycardias) or irregular heart rhythms such as premature ventricular beats.
Since beta blockers reduce the demand of the heart muscle for oxygen and the chest pain of angina pectoris occurs when the oxygen demand of the heart exceeds the supply, beta blockers can be useful in treating angina. They have also become an important drug in improving survival after a person has had a heart attack.
Thanks to their effect on blood vessels, beta blockers can lower the blood pressure and be of value in the treatment of hypertension.
Other uses for beta blockers include the prevention of migraine headaches and the treatment of certain types of tremors (familial or hereditary essential tremors).
The beta blockers (with brand names) include acebutolol (SECTRAL), atenolol (TENORMIN), bisoprolol (ZEBETA), metoprolol (LOPRESSOR, LOPRESSOR LA), and timolol (BLOCADREN). Beta blockers are also available in combination with a diuretic as, for example, with bisoprolol and hydrochlorothiazide (ZIAC).
Beta blockers reduce the pressure within the eye (the intraocular pressure), probably by reducing the production of the liquid (aqueous humor) within the eye, and so are used to lessen the risk of damage to the optic nerve and loss of vision in glaucoma. Beta blocker preparations for this purpose include timolol ophthalmic solution (TIMOPTIC) and betaxolol hydrochloride (BETOPTIC, BETOPTIC).
- Blockers, beta
Blockers, beta: A class of drugs that block beta-adrenergic substances such as adrenaline (epinephrine), a key agent in the “sympathetic” portion of the autonomic (involuntary) nervous system. By blocking the action of the sympathetic nervous system on the heart, beta blockers relieve stress on the heart. They slow the heart beat, lessen the force with […]
Blood: The familiar red fluid in the body that contains white and red blood cells, platelets, proteins, and other elements. The blood is transported throughout the body by the circulatory system. Blood functions in two directions: arterial and venous. Arterial blood is the means by which oxygen and nutrients are transported to tissues while venous […]
- Blood bank
Blood bank: : A place where blood is collected from donors, typed, separated into components, stored, and prepared for transfusion to recipients. A blood bank may be a separate free-standing facility or part of a larger laboratory in a hospital. Separation of blood: Typically, each donated unit of blood (whole blood) is separated into multiple […]
- Blood blister
Blood blister: a blister full of blood due to a pinch, bruise or repeated friction. A blister is medically termed a vesicle. One that is more than 5 mm in diameter is called a bulla. The word “blister” entered English in the 14th century. It came from the Middle Dutch “bluyster”, blister and was a […]
- Blood cleaner
Blood cleaner: A process designed to eliminate most pathogens — viruses, bacteria and fungi — from donated blood. The process is termed “pathogen inactivation.” It depends upon the fact that three components of blood that are given in transfusions — red blood cells to carry oxygen, platelets to help blood clot and plasma for clotting […]