What is the initial dose of norepinephrine (Levophed) for a 60 kg patient requiring continuous infusion?

Norepinephrine Dosing Calculation for a 60 kg Patient

For a 60 kg patient requiring continuous norepinephrine infusion for 24 hours, prepare a solution of 4 mg norepinephrine in 250 mL D5W (concentration 16 μg/mL) and start at 0.05-0.1 μg/kg/min, which equals 3-6 μg/min or 11.25-22.5 mL/hour. 1, 2

Preparation of Norepinephrine Solution

• Standard adult concentration: Add 4 mg of norepinephrine to 250 mL of D5W to yield a concentration of 16 μg/mL 1
• Alternative preparation: Add the content of one vial (4 mg/4 mL) to 1,000 mL of a 5% dextrose solution, creating a concentration of 4 μg/mL 2
• Always use dextrose-containing solutions as diluent to protect against oxidation and loss of potency 2

Initial Dosing Calculation

• Starting dose range for adults: 0.05-0.1 μg/kg/min 1

• For a 60 kg patient:

  • 0.05 μg/kg/min × 60 kg = 3 μg/min
  • 0.1 μg/kg/min × 60 kg = 6 μg/min 1, 2

• Converting to mL/hour with 16 μg/mL concentration:

  • 3 μg/min = 3 μg/min × 60 min/hr ÷ 16 μg/mL = 11.25 mL/hour
  • 6 μg/min = 6 μg/min × 60 min/hr ÷ 16 μg/mL = 22.5 mL/hour 1

Titration Guidelines

• Monitor blood pressure and heart rate every 5-15 minutes during initial titration 1
• Adjust the rate to establish and maintain a low normal blood pressure (usually 80-100 mmHg systolic) 2
• In previously hypertensive patients, aim to raise blood pressure no higher than 40 mmHg below the preexisting systolic pressure 2
• Average maintenance dose typically ranges from 2-4 μg/min (0.03-0.07 μg/kg/min for a 60 kg patient) 2
• Titrate dose according to patient response, as great individual variation occurs 2

Administration Considerations

• Central venous access is preferred for administration of norepinephrine 1
• If central access is unavailable or delayed, peripheral IV can be used temporarily 1
• Avoid abrupt withdrawal; reduce infusion gradually when discontinuing 2

Monitoring Parameters

• Target parameters: Mean arterial pressure ≥65 mmHg, urine output ≥0.5 mL/kg/h, or decreased serum lactate ≥10% from baseline 3
• Monitor for signs of excessive vasoconstriction, such as cold extremities and decreased urine output 1
• Watch for potential side effects including hypertension, arrhythmias, and tissue ischemia 1

Special Considerations

• Recent research suggests that weight-based dosing may not be necessary in obese patients, who typically require lower weight-based doses but similar absolute doses compared to non-obese patients 4, 5
• For severe cardiovascular failure, doses may need to be increased; doses >0.4 μg/kg/min are considered high-dose therapy and are associated with increased mortality 6
• Early administration of norepinephrine in septic shock has been shown to increase shock control rates within 6 hours 3

Duration of Therapy

• Continue infusion until adequate blood pressure and tissue perfusion are maintained without therapy 2
• For the 24-hour continuous infusion, prepare enough solution in advance or have additional solution ready to avoid interruption in therapy 2