Beta blockers or beta-adrenergic blocking agents are certain drugs used to treat a variety of heart conditions and other diseases. They block the action of beta-type adrenergic receptors in the body. The hormone epinephrine (adrenaline) stimulates the sympathetic nervous system by acting on these receptors.
There are two types of beta receptors: beta 1 receptors located mainly in the heart, and beta 2 receptors located all over the body, but mainly in the lungs, muscles and arterioles.
If epinephrine acts on beta 1 receptors, the heart rate and the blood pressure increase, and the heart itself requires more oxygen. Drugs that block these beta 1 receptors therefore have the opposite effect: they lower the heart rate and blood pressure and are useful when the heart itself is deprived of oxygen. They are often prescribed after heart attacks.
Drugs that block beta 2 receptors generally have a relaxing effect and are prescribed for anxiety, migraine and alcohol withdrawal syndrome[?], among others.
Non selective beta blockers should not be used in patients with Asthma or any reactive airway disease. Doing so can block the effects of Beta-2 agonists such as albuterol.
