Antihypertensive Medications
Many different medication classifications are used to treat hypertension. It is important to understand the different mechanisms of action for different classes of anti-hypertensives because clients are often on a combination of medications that work synergistically to manage blood pressure. These medications are also discussed in the “Autonomic Nervous System” chapter, with more information provided regarding the specific receptors they affect.
Alpha-2 Agonist
Clonidine is an Alpha-2 agonist. You can read more information about Alpha-2 agonists in the “Autonomic Nervous System” chapter.
Mechanism of Action
Clonidine stimulates the alpha-adrenergic receptors, resulting in vasodilation and decreased blood pressure, thus decreasing peripheral resistance, increased blood flow to the kidneys, and decreased afterload.
Indications for Use
Clonidine is used to treat hypertension and ADHD.
Nursing Considerations Across the Lifespan
Monitor BP and pulse rate. Dosage is usually adjusted to the client’s blood pressure because it can cause hypotension, bradycardia, and sedation. Rebound hypertension may occur if stopped abruptly.[1]
Client Teaching & Education
Clients should be compliant with medication therapy and take the medication at the same time each day. They should be careful not to take more than the prescribed dose within a 24-hour period, or abruptly cease medication, as rebound hypertension might occur. Medications may cause orthostatic changes, so individuals should change positions slowly. Additionally, medications may cause dry mouth and dry eyes. Individuals should also avoid the use of alcohol and other CNS depressants while taking these medications.[2]
ACE Inhibitor (Angiotensin Converting Enzyme)
Captopril is an example of an ACE (angiotensin converting enzyme) inhibitor.
Mechanism of Action
This medication blocks the conversion of Angiotensin I to Angiotensin II in the renin-angiotensin-aldosterone system. This will lead to vasodilation and sodium and water excretion by blocking aldosterone. See more information about the renin-angiotensin-aldosterone system in the “Review of Basic Concepts” section of this chapter.
Indications for Use
Captopril is used to treat hypertension and heart failure. This medication also helps reduce diabetic nephropathy.
Nursing Considerations Across the Lifespan
Do not administer to clients who are pregnant. Use with caution with clients who have diabetes.
Avoid use with other medications that increase potassium. This medication may increase risk of lithium toxicity.
Adverse/Side Effects
Black Box Warning: Clients who become pregnant should discontinue this medication due to the risk of fetal harm or fetal death.
Clients taking this medication may experience hypotension, cough, hyperkalemia, increased risk of infection, angioedema, anaphylactoid reactions, or proteinuria. Clients who experience increased facial swelling or difficulty swallowing or breathing should seek emergency medical attention. Report a persistent cough or angioedema to the health care provider.[3]
Client Teaching & Education
Medications should be taken as directed. Clients taking ACE inhibitors should be cautioned to avoid salt substitutes or foods high in potassium. Additionally, the medication may alter the sense of taste, but this generally resolves within 2-3 months of medication therapy.
Clients taking ACE inhibitors may also experience a persistent cough throughout the duration of medication therapy.[4]
Angiotensin II Receptor Blocker (ARB)
Losartan is an example of an Angiotensin II receptor blocker, also referred to as an ARB. ARBs are similar to ACE inhibitors in that they act on the renin-angiotensin-aldosterone system (RAAS). However, the difference is that they block Angiotensin II and cause vasodilation and decreased peripheral resistance, but are not likely to cause the cough that ACE inhibitors can.
Mechanism of Action
Losartan blocks Angiotensin II in the renin-angiotensin-aldosterone system to produce vasodilation.
Indications for Use
ARB is used to treat hypertension and to prevent nephropathy in diabetic clients.
Nursing Considerations Across the Lifespan
Do not administer to clients who are pregnant. It is not recommended for children under 6. Anticipate dosage adjustment with hepatic impairment. This drug can cause renal impairment and hyperkalemia.
Adverse/Side Effects
Black Box Warning: Clients who become pregnant should discontinue this medication due to the risk of fetal harm or fetal death.
Clients taking this medication may experience hypotension, dizziness, increased risk of infection, angioedema, or proteinuria. Clients who experience increased facial swelling or difficulty swallowing or breathing should seek emergency medical attention.
Client Teaching & Education
Medications should be taken as directed, at the same time each day. Clients should not discontinue therapy unless directed to do so by their healthcare provider. Patients should be careful to avoid salt substitutes and foods with high levels of potassium. ARBs may cause orthostatic changes and patients should be cautioned to change positions slowly.[5]
A male 65-year-old client has the following medications ordered: metoprolol succinate 100 mg daily, lisinopril 5 mg daily, verapamil ER 100 mg daily, and hydrochlorothiazide 25 mg daily. He has a history of hyperlipidemia, hypertension, and coronary artery disease. The client asks the nurse, “Why do I have to take so many medications?”
- What is the class and mechanism of action of each of these medications?
- What is the nurse’s best response to the client’s question?
Note: Answers to the Clinical Reasoning and Decision Making Activities can be found in the “Answer Key” sections at the end of the book.
Vasodilator
Hydralazine is an example of a direct vasodilator.
Mechanism of Action
Hydralazine’s direct mechanism of action is unknown, but it causes vasodilation via direct relaxation of vascular smooth muscle. Peripheral vasodilation results in a reduction of blood pressure and decreased vascular resistance, resulting in increased cardiac output.
Indications for Use
Vasodilators are used to treat hypertension.
Nursing Considerations Across the Lifespan
Use with caution in clients with coronary artery disease, mitral valve rheumatic heart disease, and cerebral vascular accidents.
This medication should only be used in pregnancy if the benefits outweigh the risks, due to lack of safety studies.
Adverse/Side Effects
Clients should be monitored for infection and are at risk of developing systemic lupus erythematosus (SLE). SLE is a chronic disease that causes inflammation in connective tissues. The signs and symptoms of SLE vary among affected individuals and can involve many organs and systems, including the skin, joints, kidneys, lungs, central nervous system, and blood-forming (hematopoietic) system. A characteristic sign of SLE is a flat, red rash across the cheeks and bridge of the nose. This rash is called a “butterfly rash” because of its shape.
Hypotension, palpitations, angina, tremors, numbness, tingling, disorientation, nasal congestion, headache, nausea, vomiting, and diarrhea are effects associated with hydralazine.[6]
Client Teaching & Education
Clients should remain compliant with the therapeutic dosing regimen, even if symptoms resolve. The client should be cautious not to double up on medication doses. Additionally, the client should consult the healthcare provider for follow-up instruction if two or more doses of medication are missed. Clients should be instructed to monitor their weight and assess for fluid retention in the feet and ankles. Additionally, the medication can cause side effects of orthostatic hypotension and drowsiness.[7]
Beta-1 Antagonists
Metoprolol is a selective Beta-1 blocker. You can read more information about Beta-1 antagonists in the “Autonomic Nervous System” chapter.
Mechanism of Action
Metoprolol primarily blocks Beta-1 receptors in the heart, causing decreased heart rate and decreased blood pressure. However, higher doses can also block Beta-2 receptors in the lungs, causing bronchoconstriction.
Indications for Use
Metoprolol is commonly used to treat high blood pressure, chest pain due to poor blood flow to the heart, and several heart conditions involving an abnormally fast heart rate. It is used as an early intervention during myocardial infarction (MI) to reduce the workload of the heart.
Nursing Considerations Across the Lifespan
ER formulations should not be crushed. Assess the client’s apical pulse rate before administering; if it is less than 60 beats/minute, withhold the drug and call the prescriber immediately, unless other parameters are provided. In diabetic clients, monitor glucose level closely because the drug masks common signs and symptoms of hypoglycemia.
Adverse/Side Effects
The most serious potential adverse effects are shortness of breath, bradycardia, and worsening heart failure. Other adverse effects include fatigue, dizziness, depression, insomnia, nightmares, GI upset, erectile dysfunction, dyspnea, and wheezing. Black Box Warning: When stopping therapy, taper dosage over 1 to 2 weeks because abrupt discontinuation may cause chest pain or MI.[8]
Client Teaching & Education
Clients should be compliant with medication therapy and take the medication at the same time each day. Do not abruptly cease medication, as arrhythmias, hypertension, or ischemia may develop. Clients and their families should be instructed to check pulse and blood pressure and report abnormalities to the healthcare provider. Additionally, these medications may cause side effects of dizziness and cold sensitivity.[9]
Metoprolol Medication Card
Now let’s take a closer look at the medication card for metoprolol in Table 6.10.[10] Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.
Medication Card 6.10.1: Metoprolol
Class: Antihypertensives– Beta 1 Antagonist also called beta blockers
Prototypes: Metoprolol
Mechanism: Metoprolol primarily blocks Beta-1 receptors in the heart, causing decreased heart rate and decreased blood pressure. However, in higher doses can also block Beta-2 receptors in the lungs, causing bronchoconstriction
Therapeutic Effects
- Decrease workload of heart
- Decreases blood pressure
- Decreases Heart Rate
Administration
- Do not crush medications
- Assess heart rate and hold medication if HR is less than 60 beats per minute
- Monitor blood pressure daily report abnormal BP and HR to MD
- Take as ordered at the same time every day
Indications
- High blood pressure
- Chest pain in people with poor blood flow to heart
- Tachycardia and rapid arrhythmias
- Early intervention for myocardial infarction to decrease workload of heart
Contraindications
- Asthma or respiratory diseases can be affected with the higher dose when beta 2 is stimulated resulting in cough
Side Effects
- Fatigue
- Dizziness
- Depression
- Insomnia
- Nightmares
- GI upset
- Erectile dysfunction
- Dyspnea
- Wheezing
- Cold sensitivity
- SAFETY: When tapering dosage make sure to do it slowly over a few weeks, abrupt drop can cause chest pain and MI
Nursing Considerations
- Commonly masks hypoglycemia so check diabetic blood sugars regularly
- This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. ↵
Chronically elevated blood pressure.