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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 agonist activity (vasoconstriction) and moderate beta-1 agonist activity (inotropy). It is the first-line vasopressor for most forms of shock.
## Primary Indications
* Acute hypotensive states (e.g., septic shock, cardiogenic shock).
* Hemodynamic support during cardiac arrest.
## Adult Dosing
* **Initial Infusion:** 0.05–0.1 mcg/kg/min or 2–4 mcg/min.
* **Titration:** Titrate to achieve target Mean Arterial Pressure (MAP), typically ≥65 mmHg.
* **Usual Maintenance Range:** 0.05–0.5 mcg/kg/min.
* **Maximum:** There is no strict physiological maximum, but doses >1 mcg/kg/min are associated with significant risks of end-organ ischemia and refractory tachycardia.
* *Note: Dosing should follow institution-specific protocols.*
## Pediatric Dosing
* **Continuous Infusion:** Start at 0.05–0.1 mcg/kg/min.
* **Titration:** Titrate by 0.05–0.1 mcg/kg/min every 5–15 minutes as needed.
* **Maximum:** Generally up to 1–2 mcg/kg/min in severe shock states.
* *Note: Refer to PALS or local PICU protocols due to weight-based sensitivity.*
## Dose Adjustments
* **Renal/Hepatic:** No standardized adjustments; monitor end-organ perfusion closely.
* **Transitioning:** Taper gradually to avoid rebound hypotension.
## Contraindications
* Hypersensitivity to norepinephrine or sulfites.
* Hypotension due to uncorrected blood volume deficit (except as an emergency measure).
* Mesenteric or peripheral vascular thrombosis (relative contraindication).
## Adverse Effects
* **Cardiovascular:** Hypertension, arrhythmias (tachycardia/bradycardia), myocardial ischemia.
* **Dermatologic:** Extravasation can cause severe tissue necrosis and sloughing.
* **Other:** Metabolic acidosis (secondary to peripheral vasoconstriction/hypoperfusion), headache, anxiety.
## Key Drug Interactions
* **MAO Inhibitors/TCAs:** May cause severe, prolonged hypertension.
* **Beta-blockers:** May result in unopposed alpha-adrenergic activity (severe vasoconstriction/hypertension).
* **Inhalation Anesthetics:** May increase cardiac sensitivity to arrhythmias.
## Monitoring
* **Continuous arterial pressure monitoring** is strongly recommended.
* **Heart rate and ECG** for arrhythmia detection.
* **Urine output** as a proxy for organ perfusion.
* **Infusion site:** Inspect for signs of extravasation (pallor, coldness, induration).
## Clinical Pearls
* **Extravasation Management:** If extravasation occurs, discontinue infusion and infiltrate the area with **phentolamine mesylate** (5–10 mg in 10 mL saline) locally to block alpha-receptors.
* **Prefer Central Access:** Due to high risk of tissue necrosis, administer via a large-bore central venous catheter whenever possible.
* **Compatibility:** Administer in D5W or NS. Do not mix with sodium bicarbonate or alkaline solutions as they inactivate catecholamines.
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**Disclaimer:** This information is for educational purposes only. Always consult your institution’s latest clinical guidelines, formulary, and official product labeling before prescribing or administering medication.
