Beta adrenergic blocking agents:A class ofdrugs, also calledbeta 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 theheart, these agents relievestresson 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 treatabnormal 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 thechest painofangina pectorisoccurs when the oxygen demand of the heart exceeds the supply, beta blockers can be useful in treatingangina．They have also become an important drug in improving survival after a person has had aheart attack．
Thanks to their effect on blood vessels, beta blockers can lower the官网地址bwinand be of value in the treatment ofhypertension．
Other uses for beta blockers include thepreventionofmigraineheadachesand the treatment of certain types oftremors(familialorhereditary essentialtremors).
The beta blockers (with brand names) includeacebutolol(SECTRAL),atenolol(TENORMIN),bisoprolol(ZEBETA),metoprolol(LOPRESSOR, LOPRESSOR LA,TOPROL XL),nadolol(CORGARD), andtimolol(BLOCADREN). Beta blockers are also available in combination with a diuretic as, for example, withbisoprolol and hydrochlorothiazide(ZIAC).
Beta blockers reduce the pressure within the eye (theintraocular 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 theoptic nerveandloss of visioninglaucoma．β-受体阻滞药准备这一目的includetimolol ophthalmic solution(TIMOPTIC) andbetaxololhydrochloride (BETOPTIC, BETOPTIC).
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