Medication Update

Christy L. Collard, PharmD, Department of Primary Care, Ralph H. Johnson VA Medical Center, Charleston, SC.

South Med J. 2001;94(11) 

In This Article

Beta Blockers

Mode of Action

Blockade of Beta-1 receptors, primarily located in cardiac tissue, results in decreased heart rate, decreased contractility, slowed AV conduction, and suppression of automaticity.

Contraindications

Hypersensitivity to the particular beta blocker agent, cardiogenic shock or overt cardiac failure, severe sinus bradycardia, second and third degree heart block, bronchial asthma or chronic obstructive pulmonary disease.

Adverse Effects

Cardiac side effects include hypotension and bradycardia. CNS side effects include depression, headache, dizziness, and insomnia. Beta blockers may cause cholesterol abnormalities (increase in triglycerides and LDL, decrease in HDL). These agents may induce bronchospasm and antagonize the effects of bronchodilator medications (albuterol) used for the treatment of asthma. Beta blockers have been reported to cause sexual dysfunction, primarily decreased libido and impotence.

Drug-Drug Interactions

Concomitant use of beta blockers with alpha-1 antagonists may result in an exaggerated hypotensive response to the first dose of the alpha antagonist. This is due to suppression of the beta-mediated compensatory mechanism of increased heart rate in response to alpha blockade. Calcium channel blockers, digoxin, amiodarone, and quinidine may have additive cardiovascular effects when used in combination with beta blockers. The actions of beta-2 agonist medications (eg, albuterol) may be antagonized, thus lessening their effectiveness. Hypotension may occur when beta blockers are used in conjunction with fentanyl anesthesia.

Beta blockers interact with numerous agents, and these interactions vary depending upon the agent selected.

Drug-Food Interactions

Beta blockers should be taken in a consistent manner in relation to food consumption, to help prevent fluctuations in bioavailability.

Available Agents

acebutolol*†: Sectral.

atenolol*: Tenormin.

betaxolol*: Kerlone.

bisoprolol*: Zebeta.

carteolol†: Cartrol.

carvedilol**: Coreg.

labetolol**: Normodyne.

metoprolol*: Lopressor, Toprol-XL.

nadolol: Corgard.

penbutolol†: Levatol.

pindolol† : Visken.

propranolol: Inderal, Inderal-LA.

timolol: Blocadren.

Recommended Dose

Depends upon the agent chosen.

Dosage Forms Available

Available in many different dosage strengths.

Manufacturer

Various.

References

  1. DRUGDEX System. Hutchison TA, Shahan DR (ed). MICROMEDEX Inc., Greenwood Village, Colo (Edition expires 2001)

  2. Martindale: The Complete Drug Reference. Sweetman S (ed). London, Pharmaceutical Press. Electronic version.

 * Relative cardioselective activity (beta-1 activity > beta-2 activity).

† Intrinsic sympathomimetic activity (ability to release catecholamines to maintain a satisfactory heart rate).
 
** Alpha blocking properties (blocks peripheral alpha receptors to produce peripheral vasodilation).

Comments

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