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Beta Blocker Types

Beta blockers, also called beta-adrenergic blocking agents, are prescription medications that act on the sympathetic nervous system to block the hormones epinephrine, or adrenaline, and norepinephrine from binding to beta receptors on the nerves. These hormones trigger the "fight or flight" response. This response increases bodily functions, such as heart rate and blood pressure, two conditions for which physicians prescribe beta blockers.

  1. Beta-1 and Beta-2 Receptors

    • Beta blockers prevent hormones from binding with beta-1 receptors and beta-2 receptors to enable treatment of medical conditions, such as congestive heart failure, arrhythmias, angina, hypertension, glaucoma, elevated eye pressure and migraines, according to Senior Health, eMedTV. The locations of beta-1 receptors are the eye, heart and kidneys. Beta-2 receptors are found in the liver, uterus, blood vessels, lungs, gastrointestinal tract and skeletal muscle.

    Cardioselective Beta Blockers

    • Cardioselective beta blockers block beta-1 receptors and treat conditions involving the heart and blood vessels. According to eMedTV, one type of cardioselective beta blocker prescribed by physicians is metoprolol (Lopressor, Toprol-XL), used to treat congestive heart failure, angina and high blood pressure. This type of beta blocker also improves survival after a heart attack. Other types of cardioselective beta blockers include acebutolol (Sectral), atenolol (Tenormin) and nebivolol (Bystolic). According to Mayo Clinic, physicians do not prescribe beta blockers to treat high blood pressure unless other medications are not effective.

    Non-Selective Beta Blockers

    • Non-selective beta blockers block the actions of beta-1 and beta-2 receptors and include drugs, such as timolol (Betimol, Blocadren, Istalol, Timoptic) and propranolol (Inderal, Inderal LA, InnoPran XL). Timolol reduces high blood pressure, prevents migraines and reduces the risk of heart attacks. In eyedrop form, this medication treats high eye pressure and glaucoma, according to eMedTV. By lessening the workload on the heart, propranolol (Inderal, Inderal LA, InnoPran XL) helps reduce the complications and damage related to long-term hypertension.

    Intrinsic Sympathomimetic Activity (ISA)

    • Some beta blockers, such as pindolol (Visken), have ISA, which produces a low-level effect of epinephrine and norepinephrine, according to Cardiovascular Pharmacology Concepts. With this slight reduction in the effect of beta blockers, blood pressure and heart rate increase. The increase benefits patients who experience bradycardia -- a slow heart rate of less than 60 beats per minute resulting from extended use of beta blockers.

    Beta Blockers and Alpha Blockers

    • Beta blockers, such as carvedilol (Coreg, Coreg CR) and labetalol (Trandate) are both beta-adrenergic and alpha-adrenergic blockers. By blocking alpha-adrenoceptors that cause contraction of vascular muscle tissue, this medication works as a vasodilator, relaxing the muscles in blood vessels to lower blood pressure and treat congestive heart failure, according to Cardiovascular Pharmacology Concepts.

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