Nitrates: High-Yield Review

Nitrates are one of the most heavily tested cardiac drug classes. This note reviews the drugs, mechanism, side effects, hold parameters, and the classic exam traps you need to recognize quickly.

Drug Identification

• Nitroglycerin — sublingual, IV, topical
• Isosorbide dinitrate — oral
• Isosorbide mononitrate — oral

Mnemonic: Nitrates end in -TRATE.

Indications

• Angina (chest pain)
• Acute coronary syndrome (ACS)
• Heart failure (IV nitroglycerin)

Mechanism of Action

• Causes vasodilation
• Dilates coronary arteries
• Decreases preload
• Improves myocardial oxygen supply

Common Side Effects

• Headache — expected effect
• Hypotension — fall risk
• Dizziness — safety concern
• Flushing — from vasodilation

Life-Threatening Risks

• Severe hypotension
• Syncope
• Reflex tachycardia

Hold Parameters

Hold the medication if any of the following are present:

• SBP < 90–100 mmHg
• Recent sildenafil (Viagra) or other PDE-5 inhibitor use
• Severe dizziness

Administration Rules

• Sublingual nitroglycerin: 1 tablet every 5 minutes
• Maximum of 3 doses
• Check blood pressure before each dose
• If chest pain persists after 3 doses, call provider or EMS
• Remove old transdermal patch before applying a new one
• Provide a nitrate-free interval with long-acting forms to prevent tolerance

Common Exam Traps

• Giving nitrates when blood pressure is low
• Ignoring recent PDE-5 inhibitor use (sildenafil, tadalafil, vardenafil)
• Mistaking the expected headache for an allergic reaction
• Swallowing sublingual nitroglycerin instead of placing it under the tongue
• Failing to remove the old transdermal patch before applying a new one

Key takeaways

• Nitrates end in -TRATE and treat angina, ACS, and heart failure through vasodilation.
• Headache is expected — not an allergy.
• Hold if SBP < 90 mmHg or if the patient took a PDE-5 inhibitor (severe hypotension risk).
• Sublingual dosing: 1 tablet every 5 minutes, max 3 doses, then call EMS if pain persists.
• Always remove the old patch before applying a new one and allow a nitrate-free interval to prevent tolerance.