What is the recommended dose for nitroglycerin (glyceryl trinitrate) infusion?

Nitroglycerin Infusion Dosing Guidelines

For intravenous nitroglycerin, the recommended initial dose is 5 mcg/min with titration in 5 mcg/min increments every 3-5 minutes until the desired clinical response is achieved, with most patients responding at doses between 10-200 mcg/min. 1, 2

Initial Dosing and Preparation

• Nitroglycerin must be diluted in 5% Dextrose or 0.9% Sodium Chloride prior to infusion 1
• Standard dilution: 50 mg in 500 mL (100 mcg/mL) or 5 mg in 100 mL (50 mcg/mL) 1
• When using non-absorbing tubing sets, start at 5 mcg/min 1
• When using standard polyvinyl chloride tubing, higher initial doses may be needed (10-20 mcg/min) due to drug absorption into the tubing 2, 3

Titration Protocol

1. Initial titration:

   • Start at 5 mcg/min when using non-absorbing tubing 1
   • Increase by 5 mcg/min every 3-5 minutes until clinical response 2, 1
   • If no response at 20 mcg/min, increase by 10 mcg/min increments 2
   • If still no response, increase by 20 mcg/min increments 2

2. Once partial response is observed:

   • Reduce the increment size
   • Lengthen the interval between dose increases 2, 1

3. Maximum dose:

   • Common ceiling dose: 200 mcg/min 2
   • Prolonged infusion (2-4 weeks) at 300-400 mcg/min has been used without increased methemoglobin levels 2
   • Maximum concentration should not exceed 400 mcg/mL 1

Monitoring Parameters

• Blood pressure (maintain systolic BP >110 mmHg, or not more than 25% below baseline if hypertensive) 2
• Signs and symptoms of ischemia 2
• Heart rate (avoid with severe bradycardia or tachycardia) 2
• Pulmonary capillary wedge pressure (when appropriate) 1

Special Considerations

Contraindications

• Systolic BP <90 mmHg or ≥30 mmHg below baseline 2, 4
• Severe bradycardia (<50 bpm) or tachycardia (>100 bpm) 4
• Right ventricular infarction 4
• Recent use of phosphodiesterase-5 inhibitors (sildenafil within 24h, tadalafil within 48h) 2, 4
• Severe aortic stenosis 4

Tolerance Management

• Tolerance typically develops after 24h of continuous therapy 2
• May require periodic dose increases to maintain efficacy beyond 24h 2
• Consider switching to oral or topical nitrates when patients are stable for 12-24h 2

Infusion Set Considerations

• Non-absorbing tubing delivers more drug than polyvinyl chloride (PVC) tubing 1, 3
• If changing concentration or tubing type, flush or replace the infusion set 1
• Beneficial hemodynamic effects can be achieved with either tubing type, but may require higher doses with PVC tubing 3

Transitioning from IV to Oral/Topical Nitrates

• When patients are free of ischemic symptoms for 12-24h, attempt to reduce IV dose 2
• Consider switching to oral or topical nitrates 2
• Discontinue IV nitroglycerin in patients who remain free of ischemic signs/symptoms 2

Nitroglycerin infusion is a potent vasodilator that requires careful titration and monitoring to achieve optimal clinical response while avoiding adverse effects such as hypotension and headache.