Contributed by: Anuolu Bank-Oni, PharmD, CDE, BCGP
Introduction
Beta-blockers have several indications. They are used in the management of cardiovascular diseases, including hypertension, angina pectoris, heart failure, acute myocardial infarction (unstable angina, ST-elevation myocardial infarction, and non-ST-elevation myocardial infarction), aortic dissection, portal hypertension, and cardiac arrhythmias. Beta-blockers are also prescribed for glaucoma, migraine prophylaxis, hyperthyroidism, essential tremors, anxiety disorders, and other conditions.
Differences between drugs within the class
Beta-blockers competitively inhibit the binding of catecholamines (epinephrine and norepinephrine) to beta receptors of the sympathetic nervous system.
Three beta receptors exist: beta-1, beta-2, and beta-3. However, beta-3 receptors are currently less clinically relevant and are involved in lipolysis.
Beta-1 receptors are located primarily in the heart, kidney, and fat cells. In contrast, beta-2 receptors are found in the heart, vascular and bronchial smooth muscle, gastrointestinal tract, uterus, liver, pancreas and eyes.
Some beta-blockers also bind to alpha-1 receptors. Alpha-1 receptors are found on vascular smooth muscles of the brain, skin, kidneys, and sphincters of the gastrointestinal system. Binding to alpha-1 receptors causes vasodilation, which is beneficial in the treatment of hypertension.
Blockage of beta-1 receptors leads to a decrease in cardiac automaticity, conduction velocity, and renin release. Conversely, blockage of beta-2 receptors produces relaxed smooth muscles and increased metabolic effects.
Based on their affinity for these receptors, beta-blockers can be classified as either cardioselective (selective for beta-1 receptors) or non-selective. The degree to which a beta-blocker binds to any of these receptors plays a role in the clinical effects produced. For example, patients with reactive airway disease should avoid non-selective beta-blockers due to the risk of bronchospasm.
Some drugs in this class also partially activate beta receptors. This partial agonist activity, also known as intrinsic sympathomimetic activity (ISA), can occur at either the beta-1 or beta-2 receptors. ISA at beta-1 receptors may result in a smaller reduction in resting heart rate and cardiac output versus beta-blockers without ISA. At beta-2 receptors, ISA may increase peripheral vasodilation. Below is a description of beta blockers highlighting the properties to consider when making treatment decisions.
| Drug | Half-life (hours) | Cardio-selective | Partial agonist activity (ISA) | Alpha antagonist effect | Main indications |
|---|---|---|---|---|---|
| Acebutolol | 3 – 4 | Yes | Yes | No | Angina; Hypertension; Ventricular arrhythmia |
| Atenolol | 3 – 9 | Yes | No | No | Angina pectoris; Hypertension; Post-myocardial infarction |
| Betaxolol | 9 – 12 | Yes | No | No | Hypertension |
| Bisoprolol | 9 – 12 | Yes | No | No | Hypertension; Heart failure |
| Carvedilol | 7 – 10 | No | No | Yes | Heart failure; Hypertension; Left ventricular dysfunction after myocardial infarction |
| Labetalol | 3 – 6 | No | No | Yes | Angina; Hypertension |
| Metoprolol tartrate | 3 – 7 | Yes | No | No | Angina pectoris; Heart failure; Hypertension |
| Metoprolol succinate (extended release) | 3 – 7 | Yes | No | No | Angina pectoris; Heart failure; Hypertension |
| Nadolol | 10 – 20 | No | No | No | Angina pectoris; Hypertension |
| Penbutolol | 5 | No | Yes | No | Hypertension |
| Pindolol | 3 – 4 | No | Yes | No | Hypertension |
| Propranolol | 3 – 4 | No | No | No | Angina pectoris; Atrial fibrillation; Capillary hemangioma; Cardiac dysrhythmias; Essential tremor; Hypertension; Hypertrophic subaortic stenosis; Migraine prophylaxis; Pheochromocytoma; Post-myocardial infarction |
| Propranolol long-acting (LA) | 8 – 11 | No | No | No | Angina pectoris; Atrial fibrillation; Capillary hemangioma; Cardiac dysrhythmias; Essential tremor; Hypertension; Hypertrophic subaortic stenosis; Migraine prophylaxis; Pheochromocytoma; Post-myocardial infarction |
| Sotalol | 12 | No | No | No | Life-threatening ventricular Arrhythmias; Symptomatic atrial fibrillation/atrial flutter |
| Timolol | 4 – 5 | No | No | No | Acute myocardial infarction; Angina pectoris; Hypertension; Migraine prophylaxis |
References
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- Betapace AF_PI [Interent] Bayer; [cited 2021 January 12]. Available from: https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/021151s010lbl.pdf
- Farzam K, Jan A. Beta Blockers. [Updated 2020 Nov 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532906/
- Jaillon P. Relevance of intrinsic sympathomimetic activity for beta blockers. Am J Cardiol. 1990;66(9):21C-23C. doi:10.1016/0002-9149(90)90758-s
- Micromedex Solutions. Class Comparison: Beta Blockers. PDF downloaded November 25, 2017.
- Nachawati D, Patel J. Alpha Blockers. [Updated 2020 Dec 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK556066/
- Oregon Health & Science University. Drug Class Review on Beta Adrenergic Blockers – Final Report. Available from: https://www.ohsu.edu/sites/default/files/2019-01/Beta-Blockers_final-report-and-evidence-tables_-update-2_unshaded_MAY_05.pdf. Published May 2005. Accessed January 12, 2021.
- RxFiles.ca. Beta Blocker (BB): Comparison Chart. Published July 2015.
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