Beta Blockers (cont.)
Annette (Gbemudu) Ogbru, PharmD, MBA
Dr. Gbemudu received her B.S. in Biochemistry from Nova Southeastern University, her PharmD degree from University of Maryland, and MBA degree from University of Baltimore. She completed a one year post-doctoral fellowship with Rutgers University and Bristol Myers Squibb.
In this Article
- What are beta blockers and how do they work?
- For what conditions are beta blockers used?
- Are there differences among beta blockers?
- What are the side effects of beta blockers?
- What are the drug interactions?
- What are some examples of beta blockers?
Are there differences among beta blockers?
Beta blockers differ by which receptors are blocked.
First generation beta blockers such as propranolol (Inderal, InnoPran), nadolol (Corgard), timolol maleate (Blocadren), penbutolol sulfate (Levatol), sotalol hydrochloride (Betapace), and pindolol (Visken) are non-selective in nature, meaning that they block both beta1 (β1) and beta2 (β2) receptors and will subsequently affect the heart, kidneys, lungs, gastrointestinal tract, liver, uterus, vascular smooth muscle, and skeletal muscle and as an effect, could cause reduced cardiac output, reduced renal output amongst other actions.
Second generation beta blockers such as metoprolol (Lopressor, Toprol XL), acebutolol hydrochloride (Sectral), bisoprolol fumarate (Zebeta), esmolol hydrochloride (Brevibloc), betaxolol hydrochloride (Kerlone), and acebutolol hydrochloride (Sectral) are selective, as they block only β1 receptors and as such will affect mostly the heart and cause reduced cardiac output.
Beta blockers such as pindolol (Visken), penbutolol sulfate (Levatol), and acebutolol hydrochloride (Sectral) differ from other beta blockers as they possess 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. ISA's have smaller effects in reducing resting cardiac output and resting heart rate, in comparison to drugs that do not possess ISA.
Beta blocker such as propranolol (Inderal, InnoPran), acebutolol hydrochloride (Sectral), and betaxolol hydrochloride (Kerlone) possess a quinidine-like or anesthetic-like membrane action, which affects cardiac action potential (electrical impulses within the heart that cause contractions).
Beta blockers such as labetalol hydrochloride (Trandate, Normodyne) and carvedilol (Coreg)
have both β- and α1-adrenergic receptors. Blocking the α1-adrenergic receptors in addition to the β blocker lowers blood pressure which provides additional vasodilatory action of the arteries.
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