Recommended Dosing for Glyceryl Trinitrate (GTN) Patches
The recommended dose for a Glyceryl Trinitrate (GTN) patch is 0.2 to 0.8 mg per hour, applied for 12-14 hours daily with a mandatory 10-12 hour nitrate-free interval to prevent tolerance. 1, 2
Dosing Guidelines
Initial Dosing
- Start with 0.2-0.4 mg/hour (5-10 mg/24h) patch 2
- Apply in the morning and remove after 12-14 hours 2
- For angina management, typical doses range from 5-15 mg/24h 1
Dose Titration
- If symptoms are not adequately controlled, increase to 0.4-0.6 mg/hour (10-15 mg/24h) 2
- Maximum recommended dose: 0.8 mg/hour (20 mg/24h) 2
Application Instructions
- Apply to clean, dry, hairless skin on the trunk or upper arm 3
- Rotate application sites to prevent skin irritation
- Use the provided applicator to ensure proper dosing 3
- For ointment formulations, apply to a 36 square inch area of skin 3
Critical Considerations for Efficacy
Preventing Nitrate Tolerance
- A daily nitrate-free interval of 10-12 hours is essential 2, 3
- Continuous 24-hour therapy leads to complete loss of anti-anginal efficacy within 24-48 hours 2, 4
- Apply patch in the morning and remove in the evening to create the nitrate-free interval during sleep 2
Clinical Pearls
- Efficacy has been demonstrated for up to 7 hours after application in controlled trials 3
- Smaller patch sizes (5-10 mg/24h) may be inadequate for 24-hour protection 4
- If nocturnal angina occurs, consider adjusting the timing of the nitrate-free interval 2
Contraindications
- Avoid in patients with:
- Systolic BP <90 mmHg or >30 mmHg below baseline
- Marked bradycardia (<50 bpm) or tachycardia (>100 bpm)
- Recent use of phosphodiesterase inhibitors (within 24h of sildenafil or 48h of tadalafil)
- Suspected right ventricular infarction 2
Side Effects
- Headache (typically resolves with continued use)
- Hypotension
- Reflex tachycardia 1
By following these dosing guidelines and ensuring a daily nitrate-free interval, you can maximize the anti-anginal efficacy of GTN patches while minimizing the development of tolerance.