Beta Blockers

Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

Beta blockers are 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 which controls many important organs and tissues in the body including the heart, blood vessels, and air passages in the lung.

By blocking the action of the involuntary nervous system on the heart, beta blockers relieve stress on the heart. They slow the heart beat and lessen the force with which the heart muscle contracts. They also reduce the force with which muscles surrounding blood vessel contract in the heart, brain, and throughout the body. This reduces the pressure in the blood vessels and/or increases the flow of blood.

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.

Beta blockers reduce the workload of the heart and thereby the demand of the heart muscle for oxygen. Since 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 by reducing the need of the heart for oxygen. They also have 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 (high blood pressure).

Other uses for beta blockers include the prevention of migraine headaches, stage fright (social phobia), 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, Toprol XL),
  
  
• nadolol (Corgard),
  
  
• timolol (Blocadren) and
  
  
• nebivolol (Bystolic).

Beta blockers are also available in combination with a diuretic [for example, 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 S).

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