What is the recommended dose of Glyceryl Trinitrate (GTN) for angina pectoris?

Recommended Dosage of Glyceryl Trinitrate (GTN) for Angina Pectoris

For angina pectoris, sublingual GTN tablets should be administered at a dose of 0.3 to 0.6 mg (up to 1.5 mg) at the onset of chest pain, which can be repeated approximately every 5 minutes until relief is obtained, for a maximum of 3 tablets in a 15-minute period. 1, 2

Sublingual and Oral GTN Formulations

• Sublingual tablets: 0.3 to 0.6 mg (up to 1.5 mg) with duration of effect 1-7 minutes 1
• Spray: 0.4 mg as needed, with similar duration to sublingual tablets 1
• Prophylactic use: GTN may be used 5-10 minutes before activities that might precipitate an anginal attack 2, 3
• Patient position: During administration, the patient should rest, preferably in the sitting position 2

Transdermal and Intravenous GTN

• Transdermal: 0.2 to 0.8 mg per hour every 12 hours, with duration of effect 8-12 hours during intermittent therapy 1, 4
• Intravenous: 5 to 200 mcg per minute, with tolerance developing in 7-8 hours 1
• IV initiation: Start at 10 mcg/min and increase by 10 mcg/min every 3-5 minutes until symptom relief or blood pressure response 1, 4
• Maximum IV dose: Although no absolute maximum is established, 200 mcg/min is commonly used as a ceiling dose 1, 4

Other Nitrate Options

• Isosorbide dinitrate: 5 to 80 mg orally 2-3 times daily (duration up to 8 hours) 1
• Isosorbide dinitrate slow release: 40 mg 1-2 times daily (duration up to 8 hours) 1
• Isosorbide mononitrate: 20 mg twice daily (duration 12-24 hours) 1
• Isosorbide mononitrate slow release: 60 to 240 mg once daily 1

Important Safety Considerations

• If chest pain persists after 3 sublingual tablets in a 15-minute period, or if pain differs from typical angina, prompt medical attention is recommended 2
• GTN is contraindicated after use of sildenafil within 24 hours, tadalafil within 48 hours, or vardenafil (exact timing not determined but generally 24 hours) due to risk of profound hypotension, MI, and death 1, 4
• Avoid GTN in patients with systolic blood pressure <90 mmHg or 30 mmHg below baseline, or with marked bradycardia or tachycardia 1, 4
• When titrating IV GTN, systolic blood pressure generally should not be reduced below 110 mmHg in previously normotensive patients or more than 25% below baseline mean arterial pressure in hypertensive patients 1, 4

Managing Nitrate Tolerance

• Tolerance to hemodynamic effects typically develops after 24 hours of continuous therapy 1, 4
• For transdermal patches, use an intermittent approach (12-14 hours on, 10-12 hours off) to avoid tolerance 4, 5
• Patients requiring IV GTN beyond 24 hours may need periodic dose increases to maintain efficacy 1, 4
• When converting from IV to oral/topical nitrates, use non-tolerance-producing regimens (lower doses and intermittent dosing) 1