What is the dose of norepinephrine (NA) at an infusion rate of 0.9ml/hr?

Norepinephrine Dose Calculation at 0.9 mL/hr

To determine the actual dose of norepinephrine at 0.9 mL/hr, you must know the concentration of your prepared solution, as norepinephrine dosing depends entirely on how the drug was diluted.

Standard Concentration Calculations

Most Common Preparation (16 mcg/mL)

• The FDA-approved standard dilution is 4 mg norepinephrine in 250 mL of D5W, yielding 16 mcg/mL 1
• At this concentration, 0.9 mL/hr delivers 14.4 mcg/hr or 0.24 mcg/min 1
• This dose falls well below the typical therapeutic range for septic shock (0.1-2 mcg/kg/min or approximately 7-140 mcg/min in a 70 kg adult) 2

Alternative Concentration for Anaphylaxis (10 mcg/mL)

• An alternative dilution uses 1 mg norepinephrine in 100 mL saline, creating a 10 mcg/mL solution 2
• At this concentration, 0.9 mL/hr delivers 9 mcg/hr or 0.15 mcg/min 3, 2
• This is also subtherapeutic for most clinical scenarios 2

Clinical Context and Appropriate Dosing

Typical Starting Doses

• For septic shock, norepinephrine should start at 0.5-3 mg/hr (8-50 mcg/min) using standard 16 mcg/mL concentration, which translates to 30-180 mL/hr 2
• The FDA recommends initial dosing of 2-3 mL/min (8-12 mcg/min) of the standard dilution, then titrating to maintain adequate blood pressure 1
• Target mean arterial pressure of 65 mmHg for septic shock 3, 2

Dose Titration Guidelines

• Increase by 0.5 mg/hr every 4 hours as needed, up to maximum 3 mg/h 2
• Monitor blood pressure and heart rate every 5-15 minutes during initial titration 2
• Doses as high as 68 mg/day may be necessary in refractory shock, though occult hypovolemia should always be suspected first 1

Critical Safety Considerations

Pre-Administration Requirements

• Correct hypovolemia with crystalloid boluses (minimum 30 mL/kg) BEFORE starting norepinephrine 2
• Vasoconstriction in hypovolemic patients causes severe organ hypoperfusion despite "normal" blood pressure 2

Administration Route

• Central venous access is strongly preferred to minimize extravasation risk 2, 1
• If central access unavailable, peripheral IV can be used temporarily with strict monitoring 3, 2
• If extravasation occurs, immediately infiltrate phentolamine 5-10 mg diluted in 10-15 mL saline at the site 2

Monitoring Requirements

• Place arterial catheter as soon as practical for continuous blood pressure monitoring 2
• Watch for signs of excessive vasoconstriction: cold extremities, decreased urine output 2
• Do not mix with sodium bicarbonate or alkaline solutions in IV line, as they inactivate norepinephrine 2

Bottom Line

A rate of 0.9 mL/hr is almost certainly an error or represents a maintenance infusion pump setting that needs immediate verification of the actual concentration and clinical appropriateness. At standard concentration (16 mcg/mL), this delivers only 0.24 mcg/min—far below therapeutic levels for any indication requiring norepinephrine 2, 1. Verify your concentration, reassess the patient's blood pressure and perfusion status, and adjust to appropriate therapeutic dosing based on clinical response 1.