What is the oral equivalent of nitroglycerin (NTG) paste?

Oral Equivalents of Nitroglycerin Paste

Isosorbide dinitrate (5-80 mg, 2-3 times daily) and isosorbide mononitrate (20 mg twice daily or 60-240 mg once daily in slow-release form) are the oral equivalents of nitroglycerin paste. 1

Nitrate Options and Formulations

Nitroglycerin (NTG) is available in multiple formulations, with oral alternatives that provide similar vasodilatory effects:

• Isosorbide dinitrate (ISDN)

  • Regular oral: 5-80 mg, 2-3 times daily (duration up to 8 hours)
  • Slow-release oral: 40 mg 1-2 times daily (duration up to 8 hours)

• Isosorbide mononitrate (ISMN)

  • Regular oral: 20 mg twice daily (duration 12-24 hours)
  • Slow-release oral: 60-240 mg once daily

• Other less common oral nitrates

  • Pentaerythritol tetranitrate: 10 mg sublingual as needed
  • Erythritol tetranitrate: 10-30 mg orally 3 times daily 1

Pharmacological Considerations

When switching from nitroglycerin paste to oral nitrates, consider these important factors:

• Bioavailability: Isosorbide mononitrate has 100% oral bioavailability, making it a reliable oral alternative 2

• Duration of action: While NTG paste typically works for 8-12 hours, oral isosorbide dinitrate lasts up to 8 hours and isosorbide mononitrate can last 12-24 hours 1

• Tolerance prevention: A nitrate-free interval of 10-14 hours daily is essential to prevent tolerance

  • For once-daily dosing: Administer in the morning
  • For multiple daily dosing: Use asymmetric scheduling (e.g., 7am, 1pm, 6pm) 2, 3

Clinical Application

When selecting an oral nitrate to replace nitroglycerin paste:

1. For short-term coverage: Isosorbide dinitrate 5-80 mg 2-3 times daily provides similar but shorter duration compared to NTG paste

2. For longer coverage: Isosorbide mononitrate extended-release 30-60 mg once daily provides consistent 24-hour coverage with fewer headaches 2

3. For patients with frequent symptoms: Consider isosorbide dinitrate in an asymmetric dosing schedule (e.g., 7am and noon) to minimize tolerance development 3

Important Precautions

• Contraindications: Avoid all nitrates with:

  • Recent use of phosphodiesterase-5 inhibitors (sildenafil within 24h, tadalafil within 48h)
  • Systolic BP <90 mmHg or 30 mmHg below baseline
  • Right ventricular infarction
  • Severe aortic stenosis 2

• Monitoring: Watch for common side effects including headache and hypotension 2

• Cross-tolerance: Be aware that patients who develop tolerance to one nitrate formulation may show reduced response to other nitrate formulations, including sublingual NTG 4

Practical Dosing Strategy

For optimal results when switching from NTG paste to oral nitrates:

• Start with isosorbide mononitrate 20 mg twice daily (morning and afternoon) or extended-release 30-60 mg once daily in the morning

• Ensure a nitrate-free interval of at least 10-14 hours to prevent tolerance

• Consider combination therapy with beta-blockers to prevent reflex tachycardia that can counteract nitrate benefits 2