6.8 Antianginal – Nitrates

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Antianginal medication is used to treat angina pectoris. Angina is chest pain caused by inadequate blood flow, resulting in hypoxia of the cardiac tissue. Angina can be chronic pain caused by atherosclerosis in coronary artery disease or acute pain caused by a myocardial infarction.

Antianginals increase blood flow to the heart or decrease oxygen demand by the heart. Nitrates promote vasodilation of coronary arteries and veins. Beta blockers and calcium channel blockers are also used to decrease workload of the heart and decrease oxygen demands.

Nitrates may come in a variety of routes, such as sublingual, extended-release tablets, creams, transdermal patches, and intravenously. The grid below focuses on administration via sublingual tablets. Sublingual tablets are prescribed PRN (“as needed”) for patients who are experiencing chronic, stable angina due to coronary artery disease.

Mechanism of Action

Nitroglycerin relieves angina by relaxing vascular smooth muscle, resulting in vasodilation.

Indications for Use

Nitroglycerin is used to relieve angina due to coronary artery disease, during times of an acute attack, or prophylactically.

Nursing Considerations Across the Lifespan

Patients taking sildenafil (Viagra) or similiar medications for erectile dysfunction in the previous 24 hours may not take nitroglycerin as this may result in a dangerous drop in blood pressure.

Nitroglycerin should not be used in pregnant women or those who are breastfeeding.

Nitroglycerin is contraindicated in patients who have severe anemia, increased intracranial pressure, hypersensitivity, or circulatory failure.

Adverse/Side Effects

Patients taking nitroglycerin may experience hypotension, palpitations, headache, weakness, sweating, flushing, nausea, vomiting, or dizziness.

Patients should allow medication to dissolve under their tongue. This route allows immediate absorption into the circulation and avoids first-pass metabolism by the liver. Patients may take up to one tablet every 5 minutes, up to 3 sublingual tablets within 15 minutes to relieve chest pain. If chest pain is not relieved after the first dose, 911 should be called. Nitroglycerin may also be used prophylactically 5 to 10 minutes prior to engaging in activities that might precipitate an acute attack.

Patient Teaching & Education

Instruct patients to avoid eating or smoking during administration as this may alter absorption. Patients should sit during administration to decrease the risk for injury due to the possibility of hypotension, dizziness, and weakness. Nitroglycerin decomposes when exposed to heat or light, so it should be stored in the original, airtight glass container. See Figure 6.24[1] for an image of nitroglycerin containers. [2]

Historically, patients have been taught to seek emergency help (call 911) if pain persists after the 3rd dose of medication. However, new guidelines from the American Heart Association urge patients to call 911 after the first dose if symptoms are not improved or become worse.[3]

Photo showing a bottle containing nitroglycerin tablets
Figure 6.24 Sublingual nitroglycerin should be stored in its original, air tight glass container

Now let’s take a closer look at the medication grid for nitroglycerin in Table 6.8.[4]

Table 6.8 Nitroglycerine Medication Grid





Administration Considerations Therapeutic Effects Adverse/Side Effects
Nitrate nitroglycerin Patients may take up to 3 sublingual tablets within 15 minutes (1 every 5 minutes) to relieve chest pain

If symptoms are not improved after the first dose or become worse, or if the pain persists after the 3rd dose of medication, seek emergency help (call 911).  Nurses should check BP after each dose

No eating or smoking during administration of SL tablet

Do not chew or crush SL tablet

Advise patients to sit while taking this medication

Decrease chest pain Hypotension and palpitations

Headache, weakness, sweating, flushing, nausea, vomiting, and dizziness

Critical Thinking Activity 6.8
Image of lightbulb in a circle

A patient was administered the first dose of nitroglycerin at 1305 for acute angina.  What should the nurse evaluate after administration?

Note: Answers to the Critical Thinking activities can be found in the “Answer Key” sections at the end of the book.

  1. "Nitroglycerin (1).JPG" by Intropin is licensed under CC BY 3.0
  2. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.
  3. O’Gara, P., Kushner, F. , Ascheim, D. , Casey, D., Chung, M., de Lemos, J., Ettinger, S., Fang, J, Fesmire, F., Franklin, B., Granger, C., Krumholz, H., Linderbaum, J., Morrow, D., Newby, L., Ornato, J., Ou, N., Radford, M., Tamis-Holland, J., Tommaso, C., Tracy, C., Woo, Y., & Zhao, D. (2013).  ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines. Circulation, 127(4). https://www.ahajournals.org/doi/full/10.1161/CIR.0b013e3182742cf6?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed
  4. This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain.


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