What is the proper method to dilute glyceryl trinitrate (nitroglycerin) for intravenous infusion?

How to Dilute IV Nitroglycerin

Dilute nitroglycerin injection in either 5% Dextrose or 0.9% Sodium Chloride to a concentration of 50-100 mcg/mL for initial use, with a maximum concentration of 400 mcg/mL for maintenance. 1

Critical Safety Warning

NEVER administer nitroglycerin as a direct IV injection—it must be diluted first. The drug is a concentrated, potent formulation that requires dilution before infusion 1.

Standard Dilution Protocol

Initial Dilution Options:

• Standard concentration (100 mcg/mL): Add 50 mg nitroglycerin to 500 mL of diluent 1
• Lower concentration (50 mcg/mL): Add 5 mg nitroglycerin to 100 mL of diluent 1

Acceptable Diluents:

• 5% Dextrose Injection
• 0.9% Sodium Chloride Injection

Do not mix nitroglycerin with any other drugs 1.

Maintenance Dilution:

After initial titration, you may increase the concentration to limit fluid administration in patients requiring fluid restriction. The maximum allowable concentration is 400 mcg/mL 1.

Critical Preparation Steps

1. Use glass bottles for dilution when possible (nitroglycerin absorbs into PVC containers)
2. Invert the bottle several times after adding nitroglycerin to ensure uniform distribution 1
3. Flush or replace the infusion set completely before changing to a new concentration—failure to do this can result in delays of minutes to hours before the new concentration reaches the patient 1

Dosing Guidance from Guidelines

Once properly diluted, the 2025 ACC/AHA guidelines recommend:

• Starting dose: 10 mcg/min 2
• Titrate to: Pain relief and hemodynamic tolerability 2

The FDA labeling specifies when using non-absorbing tubing:

• Initial dose: 5 mcg/min
• Titration: Increase by 5 mcg/min every 3-5 minutes until response
• If no response at 20 mcg/min: Increase by 10 mcg/min, then 20 mcg/min increments 1

Equipment Considerations

The type of IV tubing significantly affects drug delivery. Standard PVC tubing absorbs nitroglycerin, requiring higher doses. Non-absorbing (polyethylene) tubing delivers more drug and requires lower starting doses 1. This is why the FDA labeling emphasizes that "dosage is affected by the type of container and administration set used" 1.

Use an infusion pump capable of exact and constant delivery for precise titration 1.

Common Pitfall

Changing concentrations without flushing the line is a critical error. The old concentration remains in the dead space of the tubing and will continue to infuse at the previous rate until the new solution reaches the patient, potentially causing dangerous delays in achieving therapeutic effect or unexpected hemodynamic changes 1.