How to Prepare and Administer Nitroglycerin Infusion

Preparation and Dilution

Nitroglycerin must be diluted before infusion—never give as direct IV injection. 1

Standard dilution: Transfer 50 mg nitroglycerin into 500 mL of either D5W or 0.9% normal saline to yield 100 mcg/mL concentration 1
Alternative dilution: 5 mg nitroglycerin in 100 mL yields 50 mcg/mL 1
Maximum concentration: Do not exceed 400 mcg/mL 1
Use glass bottles when possible, as nitroglycerin absorbs into plastic containers 1
Invert the bottle several times to ensure uniform mixing 1
Critical: Use non-absorbing (non-PVC) tubing to prevent drug loss—this significantly affects dosing requirements 2, 1
If changing concentrations, flush or replace the entire infusion set before starting the new concentration to avoid delayed delivery 1

Start at 10 mcg/min when using non-absorbing tubing and titrate upward every 3-5 minutes. 2, 3

Begin infusion at 10 mcg/min through an infusion pump capable of precise delivery 2, 3, 1
Increase by 10 mcg/min increments every 3-5 minutes until symptom relief or blood pressure response occurs 2, 3
If no response at 20 mcg/min, use larger increments of 10 mcg/min, then 20 mcg/min 2, 3
Once partial response is achieved, reduce increment size and lengthen the interval between increases 2, 3
Stop titrating if symptoms resolve—no need to continue increasing for blood pressure effect alone 2, 3

Do not use nitroglycerin if systolic BP is <90 mmHg or >30 mmHg below baseline. 2, 3

Target systolic BP: Maintain ≥110 mmHg in normotensive patients 2, 3
In hypertensive patients: Do not reduce mean arterial pressure by more than 25% from baseline 2, 3
Avoid in patients with marked bradycardia or tachycardia 2, 3
Monitor blood pressure frequently during titration—an arterial line is not routinely required but facilitates management in borderline cases 2

The commonly recommended ceiling is 200 mcg/min, though higher doses can be used safely with monitoring. 2, 3, 4

Standard maximum: 200 mcg/min 2, 3, 4
Prolonged infusions at 300-400 mcg/min have been safely administered for 2-4 weeks without increasing methemoglobin levels 2
If doses exceed 200 mcg/min, consider switching to alternative vasodilators 3

Never give nitroglycerin within 24 hours of sildenafil or 48 hours of tadalafil—this can cause fatal hypotension. 2, 3, 4

Phosphodiesterase-5 inhibitors (sildenafil, tadalafil, vardenafil) create risk of profound hypotension and death 2, 3, 4
Right ventricular infarction: Use with extreme caution or avoid entirely, as these patients depend critically on preload 3, 4

Tolerance develops after 24 hours of continuous infusion—plan transition to oral/topical nitrates. 2, 3, 4

Tolerance is dose and duration dependent, typically significant after 24 hours 2, 3, 4
If therapy extends beyond 24 hours, increase infusion rate periodically to maintain efficacy 2, 3, 4
Transition strategy: Once patient is symptom-free for 12-24 hours, reduce IV dose and switch to oral/topical nitrates 2, 3
Use lower doses and intermittent dosing when possible to minimize tolerance 2, 3
If ischemia recurs during continuous therapy, consider adding nitrate-free intervals 2, 3
Avoid abrupt cessation: Gradual dose reduction is advisable as sudden discontinuation can cause rebound ischemia 2

Tubing type matters: Standard PVC tubing absorbs significant amounts of nitroglycerin, requiring much higher doses than non-absorbing tubing 1, 5
Some patients with normal left ventricular filling pressures may be hypersensitive and respond fully to doses as low as 5 mcg/min—titrate carefully 1
Do not mix nitroglycerin with other drugs in the same line 1
When using peristaltic pumps, select administration sets with drip chambers delivering approximately 60 microdrops/mL 1