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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 and beta-1 adrenergic agonist activity. It induces potent peripheral vasoconstriction and moderate inotropic stimulation, with minimal effects on heart rate compared to epinephrine.
## Primary Indications
* First-line agent for septic shock.
* First-line agent for distributive or vasodilatory shock refractory to fluid resuscitation.
* Short-term management of severe hypotension.
## Adult Dosing
* **Initial:** 0.01–0.05 mcg/kg/min (or 2–4 mcg/min).
* **Titration:** Titrate every 3–5 minutes by 0.05–0.1 mcg/kg/min (or 1–2 mcg/min) to achieve target mean arterial pressure (MAP).
* **Maintenance:** Usual range is 0.01–3 mcg/kg/min.
* **Dosing variation:** Dosing is highly dependent on local ICU protocol. Always verify institutional standing orders.
## Pediatric Dosing
* **Initial:** 0.05–0.1 mcg/kg/min.
* **Titration:** Titrate in increments of 0.05 mcg/kg/min to maintain adequate perfusion.
* **Maintenance:** Typical range 0.05–1 mcg/kg/min; higher doses may be required in refractory cases under expert supervision.
## Dose Adjustments
* **Hepatic/Renal Impairment:** No formal dose adjustments; however, monitor closely for accumulation and altered peripheral perfusion.
* **Extravasation Risk:** Reduce or discontinue dose if signs of infiltration occur.
## Contraindications
* Hypersensitivity to norepinephrine or bisulfites.
* Should not be used as sole therapy in hypovolemic patients (must correct volume status first).
## Adverse Effects
* **Common:** Hypertension, tachycardia, arrhythmias (bradycardia or bradyarrhythmia due to reflex vagal response), headache.
* **Serious:** Tissue necrosis/sloughing at injection site (due to extravasation), mesenteric/peripheral ischemia, renal insufficiency (due to excessive vasoconstriction).
## Key Drug Interactions
* **MAO Inhibitors/Tricyclic Antidepressants:** May cause severe, prolonged hypertension.
* **Alpha/Beta Blockers:** May antagonize the vasoconstrictive or cardiac effects.
* **General Anesthetics (e.g., Cyclopropane, Halothane):** Increase myocardial sensitivity to catecholamines, increasing arrhythmia risk.
## Monitoring
* **Continuous:** Hemodynamic monitoring (MAP, pulse, EKG), SpO2.
* **Vascular Access:** Monitor IV site frequently (use central venous access preferred to minimize extravasation risk).
* **Systemic:** Urine output (marker of end-organ perfusion), arterial blood gases, serum lactate levels.
## Clinical Pearls
* **Extravasation Management:** If extravasation occurs, stop the infusion immediately but leave the catheter in place for potential antidote administration (e.g., phentolamine).
* **"LEAN" Mnemonic:** Norepinephrine is often preferred over other vasopressors to minimize tachycardia.
* **Compatibility:** Administer through a large peripheral vein only if central access is unavailable and for short duration; monitor site hourly.
* **Titration:** Always transition patients off vasopressors slowly to avoid rebound hypotension.
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*Disclaimer: This information is for educational purposes only. Dosage, concentrations, and clinical protocols vary by institution and patient status. Always verify current prescribing information, local institutional guidelines, and hospital policy before administration.*
