Your Blood Pressure Medication: What Is A Beta Blocker?

Beta Blockers Are Sometimes Used To Treat Hypertension.

Beta blockers
Beta blockers are used to treat hypertension. Rafe Swan

What is a beta-blocker and how do they work?

Beta blockers are drugs that are known as beta-adrenergic blocking agents that are used to treat several medical conditions, including hypertension. They work by keeping norepinephrine and epinephrine, also known as adrenaline, from binding to a type of receptor known as a beta receptor on nerves. When your sympathetic nervous system is stimulated, which can happen when you are under stress or feel threatened, your adrenal glands release the neurotransmitters epinephrine and norepinephrine.

These chemical neurotransmitters travel through your bloodstream throughout the body to signal your cells to respond in certain ways. There are three types of beta receptors, numbered beta-1, beta-2, and beta-3.  They control different bodily functions. When treating hypertension, beta-blockers are usually targeted the beta-1 receptors in the heart and kidneys and the beta-2 receptors in the blood vessels, blocking the effects of epinephrine and norepinephrine to reduce the blood pressure by reducing heart rate and dilating the blood vessels. 

There are many different beta blockers  - here's a list of commonly used medications:

  •  atenolol (Tenormin)
  • metoprolol (Lopressor, Toprol XL)
  • Propranolol (Inderal LA, Inderal XL, Hemangeol)
  • carvedilol (Coreg)
  • acebutolol (Sectral)
  • sotalol (Betapace, Sorine)
  • nadolol (Corgard)
  • labetalol (Trandate)

In general, you can recognize this class of drug by the "ol" at the end of the generic drug name.

There are several other beta blockers commonly used, so if you're not certain about the class of drug you are taking for your hypertension, check with your doctor.

What are the differences among beta blockers?

Beta blockers vary in the type of beta receptor they block. Since different types of beta receptors are located on different organs and body systems, beta blockers can have a wide variety of effects, depending upon their selectivity.

Some beta blockers are considered "non-selective," which means they block both beta-1 and beta-2 receptors. Propranolol is an example of a non-selective beta blocker. This type of medication has an effect on the heart, lungs, and blood vessels. Other beta blockers primarily exert action on the B1 receptors, like metoprolol. Since the beta-1 receptors are located in the heart, these medications primarily affect the heart and have less effect on the blood vessels.  Drugs like carvedilol and labetalol block beta receptors and another type of receptor, the alpha-1 receptor. This adds to the effect on the blood vessels. Since norepinephrine and adrenalin cause constriction of the blood vessels, drugs that block the alpha and beta receptors will cause relaxation of the blood vessels, lowering blood pressure. 

Beta-blockers are used to treat several conditions, including hypertension.

In addition to treating hypertension, beta blockers are used to treat heart failure, angina, abnormal heart rhythms, and tremors. They are also used to prevent migraine headaches. A condition known as pheochromocytoma, which refers to a small tumor in the adrenal gland, is also treated with beta blockers, since the tumor causes the abnormal release of epinephrine and norepinephrine.

Some performers use beta-blockers to reduce the symptoms of stage fright, which include tremors and elevated heart rate.  Beta-blockers are used to treat hyperthyroidism and anxiety. There are ophthalmic beta blocker solutions that are used to treat glaucoma. They reduce the pressure in the eye by reducing production of the eye fluid known as aqueous humor. 

Side effects associated with beta blockers

Beta blockers can have side effects, although these side effects only occur in a small percentage of patients. Beta-blockers affect the respiratory system and may result in shortness of breath in patients with asthma or COPD.

Some patients complain of central nervous system problems like headaches, depression, confusion, and dizziness.  Sexual dysfunction may occur. Diabetic patients should be aware that beta blockers  mask the symptoms of low blood glucose. Common complaints include cramping and diarrhea, nausea, vomiting, and fatigue. Some patients may develop blurred vision or a rash. If you develop significant adverse effects when taking any medication, consult your doctor. Beta blockers slow the heart rate and reduce blood pressure, which is the intended therapeutic effect. Everyone does not react the same way to medications, and some people may develop heart failure or heart block if they have preexisting heart conditions and begin a beta blocker. In general, the benefits of beta blockers for treatment of patients with certain conditions that include hypertension outweigh the potential problems associated with their use.  

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