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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 adrenergic agonist activity (vasoconstriction) and moderate beta-1 adrenergic activity (inotropic effect). It is a first-line vasopressor for distributive shock.
## Primary Indications
* Severe hypotensive states (e.g., septic, cardiogenic, or neurogenic shock)
* Adjunct in cardiac arrest (if ACLS protocols dictate)
## Adult Dosing
* **Initial:** 0.05–0.1 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate to achieve target Mean Arterial Pressure (MAP), typically ≥65 mmHg.
* **Maintenance:** Generally ranges from 0.01 to 3 mcg/kg/min.
* **Note:** Dosing varies by institutional protocol. Always verify concentration (e.g., 4 mg/250 mL or 8 mg/250 mL).
## Pediatric Dosing
* **Initial:** 0.05–0.1 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate by 0.05–0.2 mcg/kg/min every 5–15 minutes as needed.
* **Range:** Up to 1–2 mcg/kg/min; doses above this may require an additional pressor agent.
## Dose Adjustments
* **Renal/Hepatic:** No formal dosage adjustments; however, patients are often hemodynamically unstable, requiring frequent titration based on clinical response.
* **Dose Termination:** Taper slowly to avoid sudden hemodynamic collapse.
## Contraindications
* Hypersensitivity to norepinephrine or sulfites.
* Hypotension due to uncorrected hypovolemia (replace volume first).
* Mesenteric or peripheral vascular thrombosis (relative contraindication due to vasoconstriction).
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia (reflex), arrhythmias, myocardial ischemia.
* **Local:** Extravasation can lead to tissue necrosis/sloughing (use central line if possible).
* **Metabolic:** Hyperglycemia, lactic acidosis (at high doses).
## Key Drug Interactions
* **MAO Inhibitors/TCAs:** May cause severe, prolonged hypertensive crisis.
* **Beta-Blockers:** May lead to unopposed alpha-adrenergic vasoconstriction, causing extreme hypertension and reflex bradycardia.
* **Halogenated Anesthetics:** Increased risk of ventricular arrhythmias.
## Monitoring
* **Continuous:** Blood pressure (preferably arterial line), heart rate, and rhythm.
* **Perfusion:** MAP, urine output, serum lactate levels, and capillary refill.
* **Site:** Regularly inspect infusion site for signs of extravasation.
## Clinical Pearls
* **Extravasation Management:** If extravasation occurs, stop infusion immediately. Consider phentolamine (alpha-blocker) injection into the affected area to minimize necrosis.
* **Central Access:** Highly recommended to use a central venous catheter. If peripheral administration is necessary, infuse into a large, proximal vein for the shortest duration possible.
* **Compatibility:** Administer only via dedicated line if possible. Ensure compatibility with other IV infusions.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical protocols vary by institution. Always verify specific dosing, safety profiles, and compatibility with your local formulary and current prescribing information or pharmacist.
