Nitroglycerin Injection Guidelines

Initial Setup and Dosing

The American College of Cardiology recommends initiating intravenous NTG at a rate of 10 mcg per minute through continuous infusion via nonabsorbing tubing and increased by 10 mcg per minute every 3 to 5 minutes until symptom relief or blood pressure response is noted 1, 2
Begin IV NTG at 10 mcg/min via continuous infusion using nonabsorbing tubing, and titrate upward by 10 mcg/min increments every 3-5 minutes until one of the following occurs: relief of ischemic symptoms, desired blood pressure response, or development of side effects such as headache or hypotension 2, 3

If no response is seen at 20 mcg/min, continue with 10 mcg/min increments, and at higher doses, increments of 20 mcg/min may be used 1, 2
Once symptoms are relieved, no further dose increases are needed even if blood pressure hasn't changed significantly, but if symptoms persist, continue increasing until blood pressure response is observed 2, 3

Although no official maximum dose is established, a ceiling of 200 mcg/min is commonly used, and even prolonged infusion at higher doses does not increase methemoglobin levels 1, 3
Tolerance typically develops after 24 hours of continuous therapy, and for patients requiring NTG beyond 24 hours, periodic dose increases may be needed to maintain efficacy 5

Do not titrate systolic BP below 110 mmHg in previously normotensive patients, and do not reduce BP more than 25% below baseline mean arterial pressure in hypertensive patients 1, 2
Avoid NTG in patients with initial systolic BP less than 90 mmHg, BP drop of 30 mmHg or more below baseline, or marked bradycardia or tachycardia 1, 2

NTG is contraindicated after use of sildenafil within previous 24 hours, tadalafil within previous 48 hours, or vardenafil until BP returns to baseline, typically 24 hours 1, 2, 3
Phosphodiesterase inhibitors can cause profound hypotension, MI, and even death when combined with nitrates 1, 3

When patients are free of ischemic symptoms for 12-24 hours, attempt to reduce IV NTG dose, and convert to oral or topical nitrates within 24 hours in stabilized patients 5, 6
Use non-tolerance producing regimens, such as lower doses and intermittent dosing, and discontinue IV NTG in patients who remain free of signs and symptoms of ischemia 5, 6

Tolerance to hemodynamic effects is dose and duration dependent, and to minimize tolerance, use intermittent dosing schedules that provide nitrate-free intervals during each 24-hour period 5
For recurrent ischemia during continuous therapy, responsiveness can often be restored by increasing the dose 5

Common side effects of NTG include headache, hypotension, and abrupt cessation of IV NTG may cause exacerbation of ischemic changes on ECG, so use graded reduction 1, 2, 6