What is the recommended dosing regimen for norepinephrine (continuous intravenous infusion) in adults and pediatric patients?

Norepinephrine Dosing

For adults with acute hypotension or shock, start norepinephrine at 8-12 mcg/min (0.05-0.2 mcg/kg/min), titrate to maintain mean arterial pressure ≥65 mmHg, with typical maintenance doses of 2-4 mcg/min. 1

Adult Dosing

Standard Preparation and Initial Dosing

• Preparation: Add 4 mg norepinephrine to 1000 mL of 5% dextrose solution (yields 4 mcg/mL concentration) 1
• Starting rate: 2-3 mL/min (8-12 mcg/min of base) 1
• Maintenance range: 0.5-1 mL/min (2-4 mcg/min of base) 1
• Maximum standard dose: 10 mcg/min 1

Alternative Concentrated Preparation

If fluid restriction is needed, prepare 1:100,000 solution (1 mg in 100 mL saline = 10 mcg/mL):

• Initial rate: 30-100 mL/hr (5-15 mcg/min)
• Titrate based on clinical response 1

High-Dose Scenarios

Occasionally, doses as high as 68 mg base daily (approximately 47 mcg/min continuous) may be necessary in refractory hypotension, though occult hypovolemia must always be excluded first 1. Recent data suggests doses >1.13 mcg/kg/min predict significantly increased mortality (47-60% mortality when this threshold is crossed) 2, making aggressive volume resuscitation and consideration of additional vasopressors critical before escalating to extreme doses.

Weight-Based Dosing Considerations

While the FDA label provides non-weight-based dosing, weight-based dosing of 0.05-0.2 mcg/kg/min is commonly used in practice 3. However, in obese patients (BMI ≥30), use actual body weight cautiously as they require lower weight-based doses (mean 0.09 mcg/kg/min) compared to non-obese patients (0.13 mcg/kg/min), though total doses are similar 4. For consistency, consider using ideal or adjusted body weight in obese patients.

Pediatric Dosing

For children with shock refractory to volume resuscitation, start norepinephrine at 0.05-0.1 mcg/kg/min and titrate to effect, with maximum doses ranging from 0.5-2.5 mcg/kg/min. 5

Pediatric Preparation (Rule of 6)

• Calculate: 0.6 × body weight (kg) = number of mg diluted to 100 mL saline
• Then 1 mL/hr delivers 0.1 mcg/kg/min 6

Pediatric Dosing Range

• Starting dose: 0.5 ± 0.4 mcg/kg/min 5
• Maximum dose: Mean 2.5 ± 2.2 mcg/kg/min (range up to 5 mcg/kg/min may be necessary) 5
• Titrate to maintain adequate perfusion and blood pressure

Critical Administration Principles

Volume Resuscitation First

Blood volume depletion must be corrected as fully as possible before vasopressor administration 1. Adults should receive 1-2 L normal saline at 5-10 mL/kg in first 5 minutes; children up to 30 mL/kg in first hour 6. The only exception is when intraaortic pressures must be maintained emergently to prevent cerebral or coronary ischemia—in this case, norepinephrine can be given concurrently with volume replacement 1.

Route of Administration

• Preferred: Central venous catheter into large vein 1
• Peripheral administration is safe when protocol-based: Recent data shows peripheral norepinephrine avoided central line placement in 51.6% of patients, with extravasation rate of 75.8 events/1000 catheter-days, causing minimal tissue injury and no cases requiring surgical intervention 7. However, peripheral use should follow strict protocols with frequent monitoring and be limited to short durations (median 3 hours in pediatric data) 5
• Intraosseous route is safe in children for median 3 hours without adverse effects 5

Dilution Requirements

• Must dilute in 5% dextrose or 5% dextrose with sodium chloride 1
• Never use saline alone—dextrose protects against oxidation and potency loss 1
• Adjust concentration based on fluid requirements (more dilute if large volumes needed, more concentrated if fluid restriction required) 1

Monitoring and Titration

• Target blood pressure:
  • Normotensive patients: 80-100 mmHg systolic 1
  • Previously hypertensive: No higher than 40 mmHg below preexisting systolic 1
  • Modern target: Mean arterial pressure ≥65 mmHg
• Continuous hemodynamic monitoring essential when available 1
• Central venous pressure monitoring helpful to detect occult hypovolemia 1
• Titrate every few minutes based on response

Discontinuation

Reduce gradually, avoiding abrupt withdrawal 1. Treatment duration varies widely—some patients with acute MI-related shock required up to 6 days of therapy 1.

Common Pitfalls

1. Starting norepinephrine before adequate volume resuscitation—always ensure fluid repletion first unless emergent cerebral/coronary perfusion at risk
2. Using saline as diluent—must use dextrose-containing solutions to prevent oxidation
3. Extravasation injury: If occurs, inject phentolamine 0.1-0.2 mg/kg (max 10 mg) diluted in 10 mL saline intradermally at site 8
4. Assuming hypovolemia is corrected when high doses needed—always reassess volume status when doses exceed 0.4 mcg/kg/min (associated with 40% mortality) 9
5. Using actual body weight in obese patients—consider ideal or adjusted body weight to avoid relative underdosing

Dose-Mortality Relationship

Norepinephrine dose correlates with mortality risk 9, 2:

• Low dose (<0.2 mcg/kg/min): 14% mortality
• Intermediate (0.2-0.4 mcg/kg/min): 26% mortality
• High dose (>0.4 mcg/kg/min): 40% mortality
• Critical threshold (>1.13 mcg/kg/min): 47-60% mortality

These thresholds should prompt aggressive reassessment of volume status, consideration of additional vasopressors (vasopressin, epinephrine), and evaluation for reversible causes of shock.