Beta-Blockers Pharmacology Practice Questions with Answers and NCLEX® Review

Introduction to Beta-Blockers

The most prescribed indication is hypertension in clients who have either tachycardia (HR > 100 bpm) or in clients with hypertension that was not reduced after initiating other blood pressure medications (e.g. ACE inhibitors, ARBs).

Other common indications include atrial fibrillation or 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

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Beta-Blocker Indications

• 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.

Beta-Blocker Types

MOA

MOAs 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 the sympathetic nervous system, the “fight or flight” mechanisms in your body, by preventing the ability of 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 of Beta-Blockers

Beta-blockers differ on account of their selectivity for beta 1 receptors in the body. Blockers that aren’t cardio-selective may cause blockade of other beta receptors including receptors in the lungs. This can lead to exacerbations in asthmatic clients 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 and making it difficult for clients to breathe.

It’s 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:

• Cardiovascular: It’s imperative to assess baseline blood pressure and heart rate prior to giving beta blockers to clients. 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, the usage of non-selective blockers in clients 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: Clients 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: Clients 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.

Warnings

• Caution with heart failure clients as beta-blockade can lead to worsening of congestive heart failure and significant negative chronotropy
• Avoid giving clients beta blockers with bradycardia (HR < 60 bpm)
• Clients on chronic beta blockers should be slowly titrated off the medication to prevent beta blocker withdrawal
• Overdose can lead to life-threatening bradycardia

Common Beta-Blocker Generics Table (with Selectivity)

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. This review should aid in preparing for the NCLEX^® and general practice for clients requiring these medications.

• Clients 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

Beta-Blockers Pharmacology Conclusion

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. Clients 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.

References:

1. 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.
2. UpToDate. https://www.uptodate.com/contents/Major side effects of beta blockers. Accessed April 3, 2020.
3. UpToDate. https://www.uptodate.com/contents/Atenolol: Drug information. Accessed April 3, 2020.
4. Mann SJ. Redefining beta-blocker use in hypertension: selecting the right beta-blocker and the right client. J Am Soc Hypertens. 11(1):54-65. doi:10.1016/j.jash.2016.11.007.
5. 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.
6. Prijic S, Buchhorn R. Mechanisms of Beta-Blockers Action in Clients with Heart Failure. Rev Recent Clin Trials. 2014;9(2):58-60. doi:10.2174/1574887109666140908125402.
7. 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.