Standard Dose of Sublingual Nitroglycerin
The standard dose of sublingual nitroglycerin is 0.3 to 0.6 mg per tablet, with the most commonly used dose being 0.4 mg, which can be repeated every 5 minutes for up to 3 doses (total 15-minute period) for acute angina symptoms. 1, 2
Dosing Protocol for Acute Angina
- One tablet (0.3-0.6 mg) should be dissolved under the tongue at the first sign of anginal chest pain 2
- The dose may be repeated approximately every 5 minutes until relief is obtained 1, 2
- If pain persists after a total of 3 tablets in a 15-minute period, or if the pain is different than typically experienced, prompt medical attention is recommended 2
- The onset of action is rapid, with effects occurring within 1 to 7 minutes 1
Available Formulations
- Sublingual tablets are available in 0.3 mg, 0.4 mg, and 0.6 mg strengths, with a maximum single dose of up to 1.5 mg 1
- Nitroglycerin spray delivers 0.4 mg per spray and has similar efficacy to sublingual tablets 1, 3
Prophylactic Use
- Nitroglycerin may be used prophylactically 5 to 10 minutes prior to activities that might precipitate an acute anginal attack 2
- This preemptive approach is particularly useful for predictable exertional angina 4
Administration Considerations
- Patients should sit down when taking sublingual nitroglycerin to avoid falls from lightheadedness or dizziness 2
- The tablet should be dissolved under the tongue or in the buccal pouch, not chewed, crushed, or swallowed 2
- A burning or tingling sensation may occur but should not be used as a reliable indicator of tablet potency 2
Critical Contraindications
- Nitroglycerin is absolutely contraindicated within 24 hours of sildenafil use or 48 hours of tadalafil use due to risk of profound hypotension, myocardial infarction, and death 1
- Avoid use if systolic blood pressure is less than 90 mm Hg or more than 30 mm Hg below baseline 1
- Do not use with marked bradycardia or tachycardia 1
When to Escalate to Intravenous Therapy
- If symptoms are not relieved after three 0.4-mg sublingual doses taken 5 minutes apart, intravenous nitroglycerin should be considered 1
- Intravenous therapy is also indicated for patients with heart failure or hypertension complicating their acute coronary syndrome 1
Common Pitfalls to Avoid
- Excessive use can lead to tolerance development, so only the smallest effective dose should be used 2
- Tablets must be kept in the original glass container and tightly capped after each use to prevent loss of potency 2
- Headaches are common and may actually indicate drug activity 2
- Hypotension may be accompanied by paradoxical bradycardia and increased angina, particularly in volume-depleted patients 2