When would you prescribe nitroglycerin (nitro) for angina?

From the Guidelines

I would prescribe nitroglycerin to patients experiencing angina (chest pain) due to coronary artery disease, with instructions to take one sublingual dose (0.3-0.6 mg) every 5 minutes for up to three doses, and to seek emergency medical attention if pain persists after three doses. This recommendation is based on the guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction, which suggest that patients with suspected acute coronary syndrome (ACS) should take not more than 1 dose of nitroglycerin sublingually in response to chest discomfort/pain, and call 9-1-1 immediately if symptoms are unimproved or worsening 5 minutes after taking 1 dose 1.

Key Considerations

• Patients with chronic stable angina should be instructed to repeat nitroglycerin every 5 minutes for a maximum of 3 doses and call 9-1-1 if symptoms have not resolved completely 1.
• Family members, close friends, caregivers, or advocates should be included in discussions and enlisted as reinforcement for rapid action when the patient experiences symptoms of a possible ACS 1.
• Patients should be warned about potential side effects including headache, dizziness, and hypotension, and cautioned about the risk of severe hypotension when taking phosphodiesterase-5 inhibitors (like sildenafil) 1.

Administration and Dosage

• Sublingual nitroglycerin tablets (0.3-0.6 mg) can be taken at the onset of chest pain, with instructions to take one tablet under the tongue every 5 minutes for up to three doses.
• Nitroglycerin patches (0.2-0.8 mg/hr) can be applied once daily for prevention of angina, typically worn for 12-14 hours with a 10-12 hour nitrate-free interval to prevent tolerance.
• Nitroglycerin spray (0.4 mg/spray) is an alternative to tablets, also used as needed for acute angina.

From the FDA Drug Label

One tablet should be dissolved under the tongue or in the buccal pouch at the first sign of an acute anginal attack. Nitroglycerin may be used prophylactically 5 to 10 minutes prior to engaging in activities that might precipitate an acute attack. I would prescribe nitroglycerin at the first sign of an acute anginal attack or prophylactically 5 to 10 minutes prior to engaging in activities that might precipitate an acute attack 2, 2, 2.

• The dose may be repeated approximately every 5 minutes until relief is obtained.
• If chest pain persists after a total of 3 tablets in a 15-minute period, or if the pain is different than is typically experienced, prompt medical attention is recommended.

From the Research

Indications for Nitroglycerin Prescription

• Nitroglycerin is commonly used as a first-line agent for angina in the emergency department and to manage chest pain due to acute coronary syndromes 3
• It is also a treatment option for other disease states such as acute heart failure, pulmonary edema, and aortic dissection 3
• Nitroglycerin can be used to treat variant angina, as it restores blood flow by relieving the coronary vasospasm that triggers the ischemic episode 4
• In unstable angina, nitrates alleviate angina pain 4

Contraindications and Adverse Effects

• Nitroglycerin has contraindications and adverse effects that need to be considered before prescribing 3
• Continuous delivery of nitroglycerin results in tolerance, limiting the use of this drug 5
• Nitroglycerin tolerance is caused, at least in part, by inactivation of aldehyde dehydrogenase 2 (ALDH2), an enzyme that converts GTN to the vasodilator, NO 5

Comparison with Other Therapies

• Calcium channel blockers are an important adjunct to treatment of typical exertional angina and are the treatment of choice for angina due to coronary artery spasm 6
• Ranolazine use in patients with inadequately controlled chronic angina is associated with less revascularization and all-cause and CV-related health care utilization compared to traditional AA medication 7
• Beta-blockers, Ca2+ antagonists, and organic nitrates provide relief from angina pain and improve exercise tolerance primarily through their ability to decrease oxygen demand 4