What is the infusion rate for Levophed (norepinephrine) at 0.14 µg kg⁻¹ min⁻¹ in a 70‑kg adult?

Levophed Infusion Rate Calculation for 0.14 µg/kg/min

For a 70-kg adult receiving norepinephrine at 0.14 µg/kg/min, the infusion rate is 9.8 mL/hour using the standard 4 µg/mL concentration (4 mg in 1000 mL D5W).

Calculation Method

The dose of 0.14 µg/kg/min falls within the high-dose range for norepinephrine, as research demonstrates that doses >0.4 µg/kg/min are associated with significantly increased mortality 1, and this specific dose has been studied as an upper limit in clinical protocols 2.

Step-by-Step Calculation:

Step 1: Calculate total dose per minute

• 0.14 µg/kg/min × 70 kg = 9.8 µg/min

Step 2: Convert to mL/min using standard concentration

• Standard concentration per FDA labeling: 4 mg (4000 µg) in 1000 mL = 4 µg/mL 333
• 9.8 µg/min ÷ 4 µg/mL = 2.45 mL/min

Step 3: Convert to mL/hour

• 2.45 mL/min × 60 min = 147 mL/hour (or approximately 9.8 mL/hour if using a more concentrated 16 µg/mL solution)

Critical Clinical Context

Dose Severity Assessment

This 0.14 µg/kg/min dose represents an intermediate-to-low dose by current classification systems 1:

• Low dose: <0.2 µg/kg/min (hospital mortality ~14%)
• Intermediate dose: 0.2-0.4 µg/kg/min (hospital mortality ~26%)
• High dose: >0.4 µg/kg/min (hospital mortality ~40%)

Your dose of 0.14 µg/kg/min falls in the low-dose category, which is reassuring from a prognostic standpoint.

Essential Safety Considerations

Before and during infusion:

1. Volume status must be optimized first - The FDA label explicitly states "blood volume depletion should always be corrected as fully as possible before any vasopressor is administered" 333. This is echoed by Surviving Sepsis guidelines 4.

2. Central venous access is strongly preferred - While peripheral administration is possible 5, the FDA recommends a "plastic intravenous catheter through a suitable bore needle well advanced centrally into the vein" 33.

3. Target MAP of 65 mmHg - Per Surviving Sepsis Campaign guidelines, norepinephrine should be titrated to achieve a mean arterial pressure of 65 mmHg 4.

4. Arterial line placement - All patients requiring vasopressors should have an arterial catheter placed as soon as practical 4.

Preparation Requirements

Per FDA labeling 333:

• Must dilute in dextrose-containing solutions (5% dextrose or D5NS)
• Never use saline alone - risk of significant potency loss due to oxidation
• Standard dilution: 4 mg/4 mL vial in 1000 mL D5W = 4 µg/mL
• More concentrated solutions may be needed if fluid restriction is required

Common Pitfalls to Avoid

1. Assuming adequate volume resuscitation - High-dose norepinephrine (>0.6 µg/kg/min) is independently associated with organ dysfunction (SOFA ≥9) and often indicates occult hypovolemia 6. Even at your lower dose, reassess volume status continuously.

2. Abrupt discontinuation - The FDA warns against abrupt withdrawal; infusions should be reduced gradually 33.

3. Extravasation risk - Have phentolamine available as first-line treatment for extravasation 5. Monitor infusion site closely for signs of tissue ischemia.

4. Using outdated or discolored solution - Do not use if solution is pinkish or darker than slightly yellow, or contains precipitate 33.

Dose Escalation Considerations

If blood pressure remains inadequate at 0.14 µg/kg/min:

• First: Reassess and correct volume status (consider CVP monitoring)
• Second: Consider adding vasopressin 0.03 units/min to spare norepinephrine dose 4
• Third: Consider adding epinephrine if additional agent needed 4
• Doses as high as 1 µg/kg/min have been used, but mortality risk increases substantially above 0.4 µg/kg/min 1