Norepinephrine drips are prepared by diluting a concentrated norepinephrine solution into an IV bag, most commonly yielding a final concentration of either 4 mcg/mL or 16 mcg/mL (standard concentration) or 32 mcg/mL (double concentration). The exact preparation depends on your facility’s protocol, but the underlying steps are consistent: choose the right diluent, add the correct amount of drug, mix thoroughly, and label the bag.
Standard Concentrations and How to Prepare Them
Norepinephrine comes as a 1 mg/mL concentrated solution. It’s also available in premixed bags at 4 mg/250 mL and 8 mg/250 mL in 5% dextrose. When mixing from the concentrated vial, the most common preparations are:
- 4 mcg/mL: Add 1 mg (1 mL) of norepinephrine to 250 mL of diluent.
- 16 mcg/mL: Add 4 mg (4 mL) of norepinephrine to 250 mL of diluent. This is the standard concentration used in many ICUs.
- 32 mcg/mL: Add 8 mg (8 mL) of norepinephrine to 250 mL of diluent. This double concentration is used when patients need higher doses or when fluid restriction is a concern.
When drawing from the vial, withdraw the appropriate volume using aseptic technique, inject it into the IV bag, and gently invert the bag several times to ensure even mixing. Always label the bag with the drug name, concentration, date, and time of preparation.
Choosing the Right Diluent
The product monograph for norepinephrine (brand name Levophed) recommends 5% dextrose in water (D5W) as the diluent, citing concerns about potency loss through oxidation in saline. In practice, however, multiple studies have found no meaningful stability difference between D5W and normal saline. A study published in the Canadian Journal of Hospital Pharmacy tested norepinephrine at 64 mg/L in both solutions and found no statistically significant difference in drug concentration over time (p = 0.06). A separate study confirmed that norepinephrine at both 4 mcg/mL and 16 mcg/mL remained chemically stable for seven days at room temperature under ambient light, regardless of whether D5W or normal saline was used.
That said, most hospitals still default to D5W because it aligns with the manufacturer’s labeling. Follow your facility’s policy. If a patient cannot tolerate dextrose for clinical reasons, normal saline is a pharmacologically sound alternative.
Stability After Mixing
Once prepared, norepinephrine solutions at clinically used concentrations retain over 95% of their potency for at least seven days at room temperature under normal lighting. In controlled studies, the ratio of norepinephrine concentration at 168 hours compared to baseline ranged from 95.7% to 104.5% across different concentrations and diluents. When stored at refrigerated temperatures (4°C) and protected from light, solutions can remain stable for up to 61 days. In practice, most facilities set a 24-hour expiration for hanging drips as a standard infection-control measure, so the chemical stability far outlasts the typical use window.
Dosing: Weight-Based vs. Fixed-Rate
Hospitals vary in whether they dose norepinephrine by body weight (mcg/kg/min) or as a flat rate (mcg/min). Both approaches are used in practice, and neither has a clear pharmacological advantage. The variability in how critically ill patients respond to vasopressors depends on far more than body weight alone.
A study comparing the two approaches in septic shock patients found that weight-based dosing, starting at 0.01 mcg/kg/min and titrated in 0.01 mcg/kg/min increments every 2 minutes, resulted in lower doses at the point where blood pressure goals were met. Patients in the weight-based group reached a median dose of 0.05 mcg/kg/min at goal, compared to 0.07 mcg/kg/min equivalent in the non-weight-based group. The target in both groups was a mean arterial pressure (MAP) of 65 to 70 mmHg. The clinical takeaway: weight-based dosing tends to start lower and titrate more precisely, which may reduce total drug exposure early on.
Central Line vs. Peripheral IV
Norepinephrine has traditionally required a central venous catheter because of the risk of tissue damage if the drug leaks out of a peripheral vein. However, growing evidence supports short-term peripheral administration under specific safety protocols. In a prospective study, norepinephrine at 16 mg in 250 mL D5W was safely given through peripheral IVs with several safeguards: ultrasound-confirmed catheter placement, blood return checks every 2 hours, and a maximum peripheral dose of 15 mcg/min. The median maximum dose delivered peripherally was 10 mcg/min.
Peripheral administration is typically a bridge measure, used to start vasopressor support quickly while central access is being established. If doses exceed the peripheral protocol limit or infusion duration extends beyond 48 hours, transitioning to a central line becomes necessary.
What to Know About Extravasation
If norepinephrine leaks into the surrounding tissue, it causes intense vasoconstriction that can lead to tissue death. The affected area typically appears cold, hard, and pale. The treatment is local injection of a medication called phentolamine, an alpha-blocker that reverses the vasoconstriction. The standard approach involves infiltrating 5 to 10 mg of phentolamine diluted in 10 to 15 mL of saline directly into the extravasation site using a fine needle, distributed liberally throughout the affected area. This should happen as quickly as possible after the leak is identified.
Y-Site Compatibility Considerations
When running norepinephrine alongside other IV medications through a shared line, compatibility depends on concentration. One well-documented example: norepinephrine and furosemide are compatible when norepinephrine concentration is at or below 128 mcg/mL, but incompatible at 0.5 mg/mL (500 mcg/mL). Higher-concentration norepinephrine preparations, which are increasingly common in fluid-restricted patients, are more likely to cause precipitation or degradation when combined with other drugs at the Y-site. Always verify compatibility with your pharmacy before co-infusing, especially when using double or quadruple concentration bags.