6.8 Antianginal – Nitrates
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 clients 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: Nitroglycerin is used to relieve angina due to coronary artery disease, during times of an acute attack, or prophylactically.
Nursing Considerations: Clients taking sildenafil (Viagra) or similar 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 clients who have severe anemia, increased intracranial pressure, hypersensitivity, or circulatory failure.
Side Effects/Adverse Effects: Clients taking nitroglycerin may experience hypotension, palpitations, headache, weakness, sweating, flushing, nausea, vomiting, or dizziness.
Health Teaching & Health Promotion: Clients should allow medication to dissolve under their tongue. This route allows immediate absorption into the circulation and avoids first-pass metabolism by the liver. Clients may take up to one tablet every 5 minutes or up to three 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.
Instruct clients to avoid eating or smoking during administration as this may alter absorption. Clients 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 6.23[1] for an image of nitroglycerin containers.[2]
Historically, clients have been taught to seek emergency help (call 911) if pain persists after the third dose of medication. However, new guidelines from the American Heart Association urge clients to call 911 after the first dose if symptoms are no