Also known as beta-adrenergic blocking agents, beta blockers are medications that block the neurotransmitters norepinephrine and epinephrine (adrenaline) from binding to beta receptors on nerves. There are three types of beta receptors, with each having different functions in the human body.
- --beta-1 receptors: Found in the heart, eye, kidneys
- --beta-2 receptors: Found in the lungs, GI tract, liver, uterus, blood vessels, skeletal muscle
- --beta-3 receptors: Found in fat cells
Since beta blockers chiefly block beta-1 and beta-2 receptors, they are blocking the effects of norepinephrine and epinephrine. In doing so, they reduce heart rate and reduce blood pressure. The effects of beta blockers, therefore, are to force the heart to beat more slowly and with less force. This reduces one's blood pressure. Another effect is to open the blood vessels and improve blood flow.
Conditions for which Beta Blockers are Prescribed
Physicians prescribe beta blockers for a variety of reasons, including:
- -- Hypertension
- -- Arrhythmia
- -- Heart failure
- -- Angina (chest pain)
- -- Glaucoma
- -- Migraines
- -- Generalized anxiety disorder
- -- Hyperthyroidism
- -- Some tremors
It is not typical for beta blockers to be a frontline therapy with regard to blood pressure. Physicians will generally turn to the likes of diuretics first, and then only turn to beta blockers if other frontline medications prove ineffective.
Examples of Beta Blockers
Some of the more popular beta blockers are listed below:
- -- Atenolol (Tenormin)
- -- Acebutolol (Sectral)
- -- Metoprolol (Lopressor)
- -- Bisoprolol (Zebeta)
- -- Nadolol (Corgard)
- -- Propranolol (Inderal LA)
People with asthma are generally not prescribed beta blockers because the drugs might trigger an asthma attack. In diabetics, beta blockers can block signs of low blood pressure. They might also affect cholesterol and triglyceride levels, although these changes are temporary. Beta blockers shouldn't be stopped abruptly; they should be stopped only under a doctor's care.