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# Norepinephrine
## Overview
Norepinephrine is a potent vasopressor and inotropic agent that acts primarily on alpha-1 adrenergic receptors to cause vasoconstriction, and to a lesser extent on beta-1 adrenergic receptors to increase heart rate and contractility.
## Primary Indications
* Treatment of severe hypotension and shock, particularly distributive shock (e.g., septic shock, neurogenic shock) when fluid resuscitation alone is insufficient.
## Adult Dosing
* **Initial:** Typically initiated at 0.01 to 0.02 mcg/kg/min.
* **Titration:** titrated upward based on hemodynamic response (e.g., mean arterial pressure [MAP] goal, usually 65 mmHg).
* **Maximum:** Doses can range from 0.1 to 2 mcg/kg/min or higher in refractory shock, though higher doses are associated with increased risk of adverse events. Specific maximums depend on protocol and patient response.
## Pediatric Dosing
* **Initial:** 0.05 to 0.1 mcg/kg/min.
* **Titration:** titrated to achieve target MAP (e.g., SBP > 70 mmHg in infants, > 80 mmHg in children 1-10 years, > 90 mmHg in adolescents) or other hemodynamic parameters.
* **Maximum:** Typically up to 2 mcg/kg/min, but higher doses may be used under expert guidance. Local protocols are essential.
## Dose Adjustments
* No specific dose adjustments are routinely required for hepatic or renal impairment, as norepinephrine is rapidly metabolized. However, close hemodynamic monitoring is crucial in all patients.
## Contraindications
* Hypersensitivity to norepinephrine.
* In patients with mesenteric or peripheral vascular thrombosis; the drug may further decrease blood flow to these areas and precipitate ischemia.
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia (reflex), arrhythmias, peripheral ischemia, tissue necrosis (with extravasation), angina.
* **Other:** Headache, anxiety, tremor, dyspnea, decreased urine output.
## Key Drug Interactions
* **MAO inhibitors and tricyclic antidepressants:** May potentiate the pressor response; avoid concurrent use or use with extreme caution and reduced doses.
* **Beta-blockers:** May cause unopposed alpha-receptor stimulation leading to severe hypertension.
* **General anesthetics:** May increase myocardial irritability and risk of arrhythmias.
* **Ergot alkaloids and oxytocics:** May cause severe, prolonged hypertension.
## Monitoring
* Continuous electrocardiogram (ECG) for arrhythmias.
* Continuous blood pressure monitoring (arterial line preferred).
* Central venous pressure (CVP) and/or pulmonary artery catheter (PAC) if indicated.
* Urine output.
* Peripheral perfusion (e.g., skin temperature, capillary refill, mental status).
* Infusion site for signs of extravasation.
## Clinical Pearls
* Administer via a central venous catheter to minimize risk of extravasation and tissue necrosis.
* Have phentolamine readily available for treatment of extravasation.
* Norepinephrine is light-sensitive; protect solutions from light.
* It should be infused into a large vein or via a central venous line. If infused peripherally, it should be done with caution and close monitoring to avoid extravasation.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and local protocols before making clinical decisions. Dosing and recommendations may vary based on individual patient factors and institutional guidelines.*
