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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine acting primarily on alpha-1 adrenergic receptors (vasoconstriction) and, to a lesser extent, beta-1 adrenergic receptors (inotropic effect). It is the first-line vasopressor for most forms of shock.
## Primary Indications
* First-line treatment for septic shock.
* Hypotension refractory to fluid resuscitation.
* Acute hypotensive states.
## Adult Dosing
* **Initial:** 0.01–0.05 mcg/kg/min via continuous IV infusion.
* **Titration:** Titrate by 0.01–0.05 mcg/kg/min every 2–5 minutes to achieve target Mean Arterial Pressure (MAP), typically ≥65 mmHg.
* **Maintenance:** Generally 0.05–0.5 mcg/kg/min.
* **Maximum:** Doses >1–2 mcg/kg/min are occasionally used in refractory cases, though benefit vs. risk (ischemia) must be carefully weighed.
* *Note: Always consult local institutional protocols for specific concentration and titration ranges.*
## Pediatric Dosing
* **Initial:** 0.05–0.1 mcg/kg/min IV infusion.
* **Titration:** Titrate to effect; common range 0.05–2 mcg/kg/min.
* *Note: Pediatric dosing is highly variable based on institutional guidelines and specific clinical context.*
## Dose Adjustments
* **Renal/Hepatic Impairment:** No standard dose adjustment required; however, patients may have altered sensitivity.
* **Weaning:** Wean gradually to avoid rebound hypotension once the underlying etiology of shock is corrected.
## Contraindications
* Hypersensitivity to norepinephrine or sulfite component.
* Hypotension due to uncorrected blood volume deficit (except as emergency support until replacement therapy is completed).
## Adverse Effects
* **Cardiovascular:** Bradycardia, arrhythmias, hypertension, peripheral ischemia.
* **Extravasation:** Tissue necrosis and sloughing (treat with phentolamine infiltration if extravasation occurs).
* **Metabolic:** Hyperglycemia, lactic acidosis (at high doses due to vasoconstriction-related tissue hypoperfusion).
## Key Drug Interactions
* **MAO Inhibitors/TCAs:** May cause severe, prolonged hypertension.
* **Beta-Blockers:** May cause unopposed alpha-adrenergic stimulation, leading to severe hypertension and reflex bradycardia.
* **Cyclopropane/Halogenated Hydrocarbons:** Increased risk of myocardial irritability (arrhythmias).
## Monitoring
* **Hemodynamics:** Continuous MAP monitoring (preferably via arterial line), heart rate, and rhythm.
* **Perfusion:** Urine output, serum lactate, and capillary refill.
* **Site:** Continuous assessment for extravasation; preferably administered via a central venous catheter.
## Clinical Pearls
* **Site Selection:** Prefer central venous access; peripheral administration is feasible for short durations at lower concentrations, provided the site is monitored intensely.
* **Refractory Shock:** If requiring high-dose norepinephrine, consider adding vasopressin (typically 0.03 units/min) or hydrocortisone to minimize norepinephrine dose requirements.
* **Compatibility:** Highly acidic; check Y-site compatibility before co-administering with other medications.
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*Disclaimer: This information is for educational purposes. Dosing and clinical practices vary by institution. Always verify dosages, contraindications, and drug interactions against the most current prescribing information and your facility’s specific clinical protocols.*
