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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine acting primarily on alpha-1 adrenergic receptors, causing potent peripheral vasoconstriction, with moderate beta-1 agonist activity increasing inotropic and chronotropic cardiac output. It is the first-line vasopressor for septic shock.
## Primary Indications
* Acute hypotensive states (e.g., septic, cardiogenic, or neurogenic shock).
* Adjunctive therapy in cardiac arrest.
## Adult Dosing
* **Initial:** 0.01 to 0.05 mcg/kg/min or 2–5 mcg/min continuous IV infusion.
* **Titration:** Titrate by 0.05–0.2 mcg/kg/min every 3–5 minutes based on blood pressure response.
* **Maintenance:** Typical range is 0.01–3 mcg/kg/min.
* **Note:** Exact titration protocols vary significantly by institution; strictly follow local ICU nursing/physician order sets.
## Pediatric Dosing
* **Initial:** 0.05 to 0.1 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate to effect (target SBP based on age).
* **Maximum:** Up to 2 mcg/kg/min has been reported; higher doses require escalation of additional vasoactive agents.
## Dose Adjustments
* **Renal/Hepatic Impairment:** No specific dose adjustment guidelines exist. Use caution; monitor end-organ perfusion.
* **Elderly:** Use caution; may be more sensitive to vasoconstrictive effects; monitor for exacerbation of coronary or peripheral vascular disease.
## Contraindications
* Hypersensitivity to norepinephrine or sulfites.
* Hypotension due to uncorrected blood volume deficit (volume resuscitation is required prior to or concurrent with initiation).
## Adverse Effects
* **Common:** Hypertension, headache, bradycardia (reflex), anxiety.
* **Serious:** Extravasation necrosis (use with phentolamine rescue if infiltration occurs), cardiac arrhythmias, myocardial ischemia, mesenteric or peripheral ischemia (due to severe vasoconstriction).
## Key Drug Interactions
* **MAO Inhibitors / TCAs:** May result in severe, prolonged hypertensive crisis.
* **Beta-blockers:** May cause unopposed alpha-adrenergic vasoconstriction, leading to severe hypertension and reflex bradycardia.
* **Cyclopropane/Halogenated Hydrocarbon Anesthetics:** Increase cardiac sensitivity to catecholamines; risk of arrhythmias.
## Monitoring
* **Continuous:** Hemodynamic monitoring (arterial line preferred for titration), ECG.
* **Clinical:** Urine output, extremity perfusion, mental status, serum lactate.
* **Access:** Ensure large-bore peripheral IV or preferably a Central Venous Catheter (CVC) to minimize extravasation risk.
## Clinical Pearls
* **Extravasation:** If infiltration occurs, stop infusion immediately, disconnect, and consider infiltrating the area with 5–10 mg of phentolamine in 10 mL of saline.
* **Volume Status:** Norepinephrine is ineffective in the setting of severe hypovolemia. Optimize intravascular volume status concurrently.
* **Shelf-life:** Norepinephrine is light-sensitive; ensure the infusion bag/tubing is protected if required by institutional policy.
* **Transition:** Taper slowly to prevent rebound hypotension.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice is subject to institutional protocols and regional standards. Always verify dosing and indications against current prescribing information, package inserts, and facility-specific clinical guidelines before administration.
