What is Norepinephrine? 1
- Norepinephrine is produced endogenously and is one of the main neurotransmitters of the sympathetic nervous system
- Norepinephrine is used as a vasopressor in many clinical scenarios and can be given as an infusion or a bolus.
Mechanism of Action 1
- Norepinephrine stimulates α1- and β1-adrenergic receptors, causing vasoconstriction and maintains heart rate and contractility.
- compared to PhenylephrinePhenylephrine
, norepinephrine generally does not cause reflex bradycardia - It causes significant increases in systolic, diastolic, and mean arterial pressures, with minimal metabolic effects (i.e., no hyperglycemia).
Pharmacology 2
- Onset: ~ 1 minute
- Duration: ~2.5 minute half-life, requiring continuous infusion for sustained effect.
- Elimination: Primarily by reuptake with only a small portion metabolized and excreted in the urine.
| Drug | α1 | α2 | β1 | β2 |
|---|---|---|---|---|
| NorepinephrineNorepinephrine What is Norepinephrine? 1 Norepinephrine is produced endogenously and is one of the main neurotransmitters of the sympathetic nervous system Norepinephrine is used as a vasopressor in many cli... |
++ | ++ | + | + |
| Epinephrine Private or Broken Links The page you're looking for is either not available or private! |
++ | ++ | ++ | ++ |
| EphedrineEphedrine Mechanism of Action 1 Ephedrine is a sympathomimetic with both indirect and direct effects on catecholamine receptors: Indirect: promotes the release of endogenous norepinephrine whic... |
+ | + | + | + |
| PhenylephrinePhenylephrine |
++ | ++ | 0 | 0 |
Indications 1
- Hypotension: First-line agent in treating hypotension during severe sepsis or septic shock.
Dosage 2
Norepinephrine is generally prepared as 64 mcg/mL in the ICU. 'Dilute' norepinephrine in the OR is generally 10 mcg/mL
- Continuous Infusion: wide variety of dosing
- Low Dose: 0 - 0.1 mcg/kg/min
- Medium Dose: 0.1-0.3 mcg/kg/min
- High Dose: > 0.3 mcg/kg/min
- Bolus Dose: 10 mcg IV push
- Long durations of infusions should be delivered via central venous access due to the risk of extravasation and tissue necrosis.
- Short infusions (up to ~6 hours in sepsis) can be delivered through peripheral catheters. Dilute solutions (< 20 mcg/mL have been observed to be safe in peripheral catheters)
Complications 1
- Tachycardia and Arrhythmias: While less arrhythmogenic than epinephrine, norepinephrine can still cause tachycardia, especially at higher doses.
- End-Organ Ischemia: Excessive vasoconstriction may lead to renal, splanchnic, and peripheral ischemia, potentially resulting in organ failure
- Extravasation Injury: Extravasation of norepinephrine can lead to tissue necrosis.
Clinical Pearls 1
- Balanced Use in Coronary Artery Disease: Norepinephrine is useful in increasing perfusion pressure, but caution must be taken to balance the resultant increase in afterload.
- Splanchnic Blood Flow: May improve splanchnic perfusion in hypotensive patients but can also reduce flow at high doses due to extreme vasoconstriction.
- Vasoconstriction Risk: Central venous administration is essential to avoid peripheral vasoconstriction and necrosis from extravasation.