Beta blockers, also known as beta-adrenergic blocking agents, are drugs that block norepinephrine and epinephrine from binding to beta receptors. There are three types of beta receptors and they control several functions based on their location in the body.
Beta-1 (β1) receptors are located in the heart, eyes, and kidneys.
Beta-2 (β2) receptors are located in the lungs, gastrointestinal tract, liver, uterus, blood vessels, and skeletal muscles.
Beta-3 (β3) receptors are located in fat cells.
Beta blockers work primarily to block β1 and β2 receptors. By blocking the effect of norepinephrine and epinephrine, beta blockers are capable of reducing the heart rate and reducing the blood pressure by dilating blood vessels.
Beta blockers differ in the type of beta receptors they block and, therefore, their effects.
• Non-selective beta blockers, such as propranolol (Inderal), block β1 and β2 receptors. Therefore, non-selective beta blockers affect the heart, blood vessels, and air passages.
• Selective beta blockers, such as metoprolol (Lopressor, Toprol XL) primarily block β1 receptors. Therefore, selective beta blockers mainly act on the heart and do not affect air passages.
• Some beta blockers, such as pindolol (Visken), have intrinsic sympathomimetic activity (ISA), which means they mimic the effects of epinephrine and norepinephrine and can cause an increase in blood pressure and heart rate. Beta blockers with ISA have smaller effects on heart rate than agents that do not have ISA.
• Labetalol (Normodyne, Trandate) and carvedilol (Coreg) block beta and alpha-1 receptors. By also blocking alpha receptors, there is great blood vessel dilation involved.
References:
Medicine Net: Beta Blockers (http://www.medicinenet.com/beta_blockers/article.htm)
RX List: Beta Blockers (http://www.rxlist.com/script/main/art.asp?articlekey=79790)
October 11, 2009 at 4:53 pm |
My doctor started me out on Toprol due to my cardiomyopathy. He then changed it to Coreg because he said the Toprol wasn’t working as well as he wanted. At my last check-up it show that the lining to my heart was thinner and my lungs looked better. I am glad the meds work.
October 13, 2009 at 10:25 am |
Great information since my dad is on Coreg
October 15, 2009 at 9:26 pm |
Coreg is an excellent drug for hypertension as well as when used in CHF patients. I have seen best results when used alone or with perhaps, one-two other drugs. However, when used with multipled antihpertensives I have often seen severe bradycardia as well as hypotension. Therefore, I think it best to rule out beta blockers if numerous cardia drugs are prescribed
October 22, 2009 at 12:45 pm |
Good information since my dad is on a beta blocker