How to Prepare and Administer Nitroglycerin Infusion

Preparation and Dilution

Nitroglycerin must be diluted before infusion and cannot be given as a direct intravenous injection. 1

Standard dilution: Aseptically transfer 50 mg of nitroglycerin into a 500 mL glass bottle of either Dextrose 5% Injection or Sodium Chloride 0.9% Injection, yielding a final concentration of 100 mcg/mL 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 and non-absorbing (non-PVC) tubing to minimize drug loss from adsorption 1, 2
Invert the bottle several times after mixing to ensure uniform dilution 1
Do not mix with other drugs in the same solution 1

Start at 10 mcg/min when using non-absorbing tubing, delivered through an infusion pump capable of exact and constant delivery. 3, 4, 1

Increase by 10 mcg/min every 3-5 minutes until symptom relief or blood pressure response occurs 3, 4
At 20 mcg/min without response: Use larger increments of 10 mcg/min, then 20 mcg/min 3, 4
Once partial response is achieved: Reduce the increment size and lengthen the interval between increases 3, 4
Stop titrating if symptoms resolve—there is no need to continue increasing the dose solely for blood pressure effect 3, 4
Some patients may be hypersensitive and respond fully to doses as small as 5 mcg/min, requiring especially careful titration 1

Do not use nitroglycerin if systolic blood pressure is <90 mmHg or >30 mmHg below baseline. 3, 4

Target systolic BP: Maintain ≥110 mmHg in previously normotensive patients 3, 4
In hypertensive patients: Do not reduce mean arterial pressure by more than 25% from baseline 3, 4
Avoid in marked bradycardia or tachycardia 3, 4
Absolute contraindication: Use within 24 hours of sildenafil or 48 hours of tadalafil due to risk of profound hypotension and death 3, 4, 5
Right ventricular infarction: Use with extreme caution or avoid entirely, as these patients are critically dependent on preload 4, 5

The commonly recommended ceiling is 200 mcg/min, though higher doses can be used safely with monitoring. 3, 4, 5

Prolonged infusions at 300-400 mcg/min have been safely administered for 2-4 weeks without increasing methemoglobin levels 3, 4
Average effective dose in clinical studies was approximately 140 mcg/min 6

Tolerance develops after 24 hours of continuous infusion and is dose and duration dependent. 3, 4, 5

Beyond 24 hours: Periodic increases in infusion rate may be needed to maintain efficacy 3, 4, 5
Transition to oral/topical nitrates within 24 hours once the patient is stable and symptom-free for 12-24 hours 3, 4
Use lower doses and intermittent dosing when possible to minimize tolerance 3, 4
If ischemia recurs during continuous therapy: Increase the dose, control symptoms for several hours, then attempt to add a nitrate-free interval 3
Avoid abrupt cessation, as this has been associated with exacerbation of ischemic ECG changes; use graded dose reduction 3

Use non-absorbing tubing and an infusion pump for accurate delivery. 1

PVC tubing absorbs nitroglycerin, requiring higher doses; non-PVC tubing allows for lower, more predictable dosing 1, 2, 7
Flush the infusion set with 20 mL of the nitroglycerin solution before starting to saturate binding sites 2
If changing concentration: Flush or replace the infusion set to avoid delayed delivery of the new concentration 1
Use a peristaltic infusion pump with an administration set that delivers approximately 60 microdrops/mL, or a volumetric infusion pump with appropriate connector set 1

Continuous ECG monitoring during early hospital phase 3
Frequent blood pressure checks during titration; an arterial line is not routinely required but facilitates titration in patients with borderline pressures 3
Monitor for headache (common side effect) and hypotension 3
Auscultate for rales to detect pulmonary congestion 3