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Introduction to Beta-blockers
Beta blockers are a commonly used class of medications for patients with cardiovascular disease which is why you should review this NCLEX® Pharmacology Review of Beta-blockers. The most prescribed indication is hypertension in patients who have either tachycardia (HR > 100 bpm) or in patients with hypertension that was not reduced after initiating other blood pressure medications (e.g. ACE inhibitors, ARBs). Other common indications includes atrial fibrillation or for general anxiety disorders where the goal is to slow the heart rate in response to stress.
Beta blockers are all named with the suffix “lol” or “olol” which helps when trying to memorize this class of medications
Indications for Beta-blockers
- Hypertension: Decreased heart rate and force of contraction → decreased blood pressure and cardiac output.
- Atrial fibrillation and cardiac arrhythmia: Reduces heart rate preventing the heart from beating too quickly leading to serious cardiac events (e.g. myocardial infarction).
- Angina and myocardial infarction: Decreased heart rate reduces the cardiac demand in the heart preventing ischemia and serious damage to the heart tissue.
- Anxiety: Decreased heart rate and sympathetic (fight or flight) activity on the heart – reduces the spread of norepinephrine to the brain and body.
Types of Beta-blockers
MOA: They work by blocking beta receptors in the central nervous system which slows the heart rate and contractility of the heart. These essentially work by acting against sympathetic nervous system, the “fight or flight” mechanisms in your body, by preventing the ability for norepinephrine and epinephrine to increase heart rate and force of contraction during times of stress. By blocking this effect these medications lead to a reduction of heart rate (negative chronotropic) and force of contraction (negative inotropic) which leads to a decrease in resistance, workload, and cardiac output.
Adverse Effects: Beta blockers differ on account of its selectivity for beta 1 receptors in the body. Blockers that are not cardio selective may cause blockade of other beta receptors including receptors in the lungs. This can lead to exacerbations in asthmatic patients or in those with COPD as beta 2 blockade causes constriction of the bronchioles in the lungs. One way to remember this is to understand that albuterol – a commonly prescribed bronchodilator for asthma and COPD – is a beta 2 agonist (meaning it activates beta 2 receptors). Antagonism of the beta 2 receptors can cause the opposite effect, constricting the bronchioles in the lungs making it difficult for patients to breath.
It is also important to note that some beta blockers may affect alpha receptors which can yield other physiological effects further reducing blood pressure. Alpha 1 blockade prevents the constriction of the smooth muscle in arterioles – meaning it widens the arteries to allow for less resistance. This leads to a further reduction of blood pressure but a higher risk of severe hypotension including orthostatic hypotension.
Other Adverse Effects:
- CV: It is imperative to assess baseline blood pressure and heart rate prior to giving beta blockers to patients. Those with bradycardia (HR < 60 bpm) or systolic blood pressure (SBP < 100 mmHg) should avoid using beta blockers. Further decreasing heart rate can lead to serious hypotension and risk of low blood perfusion.
- Pulmonary: As mentioned above – usage of non-selective blockers in patient with reactive airway diseases should be strictly avoided to reduce the risk of bronchospasm.
- Heart failure exacerbations: Edema, pulmonary crackles, weight gain
- Hypoglycemia masking effect: Patients who are diabetic may fail to recognize symptoms of hypoglycemia – masked by the beta blockers.
- Orthostatic hypotension: Increased risk of falls – when going from sitting to standing
- Decreased energy with exertion: Patients may observe lower energy as HR falls – this effect tends to go away through time.
- Beta blocker withdrawal: Acute withdrawal from beta blockers can lead to morbidity and mortality – can cause exacerbation of ischemic symptoms and precipitation of a myocardial infarction or tachyarrhythmia. This is due to upregulation of sympathetic stimulation.
- Depression, fatigue, sexual dysfunction: Common side effects resulting from a reduced effect of norepinephrine on the heart causing lower energy.
- Caution with heart failure patients as beta blockade can lead to worsening of congestive heart failure and significant negative chronotropy
- Avoid giving patients beta blockers with bradycardia (HR < 60 bpm)
- Patients on chronic beta blockers should be slowly titrated off the medication to prevent beta blocker withdrawal
- Overdose can lead to life-threatening bradycardia
Table 1: Common Key Generics (Brands) – with selectivity chart
|Beta 1 Selective||Beta-1 and Beta-2 (Non-selective)||Non-Selective Beta-blocker and Alpha-1 blocker|
Example NCLEX® questions for NCLEX® Pharmacology Review of Beta-blockers:
Test Your Knowledge
A patient being prescribed a beta-blocker which works by acting against the effects of _________ and _________ in the heart causing a __________ response in the sympathetic nervous system.
- Norepinephrine and epinephrine; decreased
- Acetylcholine and dopamine; decreased
- Dopamine and epinephrine; increased
- Norepinephrine and dopamine; increased
A patient is on a beta-blocker prescribed for atrial fibrillation but has severe asthma, which of the following beta-blockers would be a good choice for this patient?
A patient was prescribed propranolol for as needed treatment of general anxiety disorder, upon taking a dose prior to an event the patient started to wheeze with shortness of breath. Antagonism of which of the following receptors led to this adverse event?
- Alpha-1 receptor
- Beta 2 receptor
- Alpha 2 receptor
- Beta 1 receptor
Key Nursing Tips for Beta-blockers:
Beta-blockers are a commonly prescribed medication indicated for an array of disease states. These are often safe medications but may be dangerous when given in certain populations. Reviewing this NCLEX® Pharmacology Review of Beta-blockers should aid in preparing for the NCLEX® and general practice for patients requiring these medications.
- Patients with pulmonary conditions (e.g. asthma, COPD) should only be prescribed beta 1 selective blockers (refer to Table 1)
- Monitor for bradycardia or hypotension – hold the blocker if HR drops below 60 or SBP < 100
- Monitor for edema (weight gain, pulmonary crackles, swelling in periphery, JVD)
- Monitor blood glucose of hypoglycemia – suggest increased frequency in blood glucose testing in diabetics who have poorly controlled blood sugar.
- Beta blockers should be titrated off slowly if there is a need to discontinue the therapy – to avoid withdrawal
Conclusion for Beta-blockers:
Beta-blockers are a very commonly prescribed class of medications indicated for a variety of treatment. They are used primarily for cardiovascular diseases as well as arrhythmias including atrial fibrillation. Generally, these medications are safe and well tolerated but may require careful consideration prior to giving medications for specific populations. Patients with a history of reactive airway disease, diabetes, or serious bradycardia conditions should only be given beta blockers with extreme caution.
Reviewing the NCLEX® Pharmacology Review of Beta-blockers should provide a strong overview of the various considerations that should be in place prior to using these in practice. A firm understanding of how this work as well the potential side effects should aid in studying for the NCLEX® exam as well as preparation for daily practice.
Example NCLEX® question for NCLEX® Pharmacology Review of Beta-blockers:
Test Your Knowledge
What would be an appropriate intervention to make for a patient with type 2 diabetes being prescribed a new beta-blocker?
- “Avoid excessive sun while using this medication”
- “This medication can mask the effect of low-blood-sugar in your body so consider testing more frequently”
- “This medication will not make you feel dizzy or week as long as you stand up slowly from a sitting or lying position”
- “Avoid exercise as this medication will make you feel weak and you may be at increased risk of falling”
- Whelton PK, Carey RM. The 2017 American College of Cardiology/American Heart Association Clinical Practice Guideline for High Blood Pressure in Adults. JAMA Cardiology. 2018;3(4):352. doi:10.1001/jamacardio.2018.0005.
- UpToDate. https://www.uptodate.com/contents/Major side effects of beta blockers. Accessed April 3, 2020.
- UpToDate. https://www.uptodate.com/contents/Atenolol: Drug information. Accessed April 3, 2020.
- Mann SJ. Redefining beta-blocker use in hypertension: selecting the right beta-blocker and the right patient. J Am Soc Hypertens. 11(1):54-65. doi:10.1016/j.jash.2016.11.007.
- Jabbal S, Lipworth BJ. Sensitivity of Lung Resistance and Compliance to Beta-Blocker Induced Bronchoconstriction and Long Acting Beta-Agonist Withdrawal in COPD. Lung. 196(1):15-18. doi:10.1007/s00408-017-0079-1.
- Prijic S, Buchhorn R. Mechanisms of Beta-Blockers Action in Patients with Heart Failure. Rev Recent Clin Trials. 2014;9(2):58-60. doi:10.2174/1574887109666140908125402.
- Prins KW, Neill JM, Tyler JO, Eckman PM, Duval S. Effects of Beta-Blocker Withdrawal in Acute Decompensated Heart Failure: A Systematic Review and Meta-Analysis. JACC. 3(8):647-653. doi:10.1016/j.jchf.2015.03.008.