Sublingual Nitroglycerin Dosing for Angina Pectoris
The recommended sublingual nitroglycerin dose for immediate relief of angina pectoris is 0.3 to 0.6 mg (up to 1.5 mg) per tablet, with one tablet dissolved under the tongue at the first sign of an acute anginal attack, which may be repeated approximately every 5 minutes until relief is obtained, for a maximum of 3 tablets in a 15-minute period. 1, 2
Dosing Protocol
- Initial dose: 0.3-0.4 mg sublingual tablet or spray
- Frequency: May repeat every 5 minutes
- Maximum: 3 doses within 15 minutes
- Duration of effect: 1-7 minutes
If chest pain persists after 3 tablets in 15 minutes, the patient should seek immediate medical attention as this may indicate a more serious condition requiring emergency intervention 1, 2.
Administration Guidelines
- Patient should sit while taking nitroglycerin to prevent falls due to potential dizziness 3
- Tablet should be dissolved under the tongue or in the buccal pouch 2
- Nitroglycerin may also be used prophylactically 5-10 minutes prior to activities that might precipitate an anginal attack 2
Monitoring and Precautions
- Monitor blood pressure after each dose
- Discontinue if systolic BP drops below 90 mmHg or 30 mmHg below baseline 1, 3
- Contraindications include:
Important Clinical Considerations
- Sublingual nitroglycerin maintains its full anti-ischemic effect after initial and intermittent long-term administration 4
- For patients with ongoing ischemic symptoms not relieved by sublingual nitroglycerin, intravenous nitroglycerin may be initiated at 10 mcg/min and titrated upward 1
- Tolerance can develop with continuous nitrate therapy, but is less likely with intermittent sublingual use for acute symptoms 4, 5
- Common side effects include headache, dizziness, and hypotension 1
When to Escalate Care
If a patient experiences chest discomfort/pain that is unimproved or worsening 5 minutes after taking one sublingual nitroglycerin dose, they should call emergency services immediately rather than continuing to self-medicate, as this approach has been documented to cause delays in seeking appropriate care 1.