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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 adrenergic agonist activity (vasoconstriction) and moderate beta-1 adrenergic agonist activity (inotropic effect). It is a first-line vasopressor for distributive shock.
## Primary Indications
* Acute hypotensive states (e.g., septic shock, cardiogenic shock).
* Adjunct in the treatment of cardiac arrest (off-label/secondary).
## Adult Dosing
* **Initial Infusion:** 0.05–0.1 mcg/kg/min or 2–4 mcg/min.
* **Titration:** Titrate by 0.05–0.2 mcg/kg/min every 3–5 minutes based on mean arterial pressure (MAP) goal (typically ≥65 mmHg).
* **Refractory Shock:** Doses rarely exceed 1–3 mcg/kg/min; however, escalation depends strictly on institutional shock protocols.
* *Note: Always consult local unit-specific dosing protocols.*
## Pediatric Dosing
* **Initial Infusion:** 0.05–0.1 mcg/kg/min.
* **Titration:** Increase by 0.05–0.1 mcg/kg/min every 5–10 minutes to maintain age-appropriate blood pressure.
* **Maximum Dose:** Generally 1–2 mcg/kg/min.
## Dose Adjustments
* **Renal/Hepatic Impairment:** No standard dose adjustment required, but use with caution in patients with severe underlying vascular disease.
* **Discontinuation:** Always taper gradually to prevent rebound hypotension.
## Contraindications
* Hypersensitivity to norepinephrine or bisulfites.
* Hypotension due to uncorrected blood volume deficit (hypovolemic shock must be addressed with fluid resuscitation before or concurrently with vasopressors).
## Adverse Effects
* **Common:** Hypertension, tachycardia, arrhythmias.
* **Serious:** Tissue necrosis/sloughing upon extravasation, limb ischemia (secondary to intense peripheral vasoconstriction), cardiac ischemia.
## Key Drug Interactions
* **MAO Inhibitors/Tricyclic Antidepressants:** May cause severe, prolonged hypertensive crisis.
* **Beta-blockers:** May result in unopposed alpha-adrenergic stimulation, leading to excessive vasoconstriction and bradycardia.
## Monitoring
* **Hemodynamics:** Continuous invasive arterial blood pressure monitoring is highly recommended.
* **Access Site:** Assess infusion site frequently for signs of extravasation.
* **Perfusion:** Monitor peripheral perfusion, urine output, and serum lactate levels (as an indicator of tissue oxygenation).
## Clinical Pearls
* **Extravasation Management:** If extravasation occurs, administer phentolamine (alpha-adrenergic antagonist) locally into the affected tissue to mitigate necrosis.
* **Site Selection:** Prefer central venous access to reduce the risk of peripheral extravasation; if peripheral use is required, use short-term, large-proximal veins and monitor closely.
* **Compatibility:** Do not dilute with saline-only if alkaline; ensure it is properly buffered per formulary instructions.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice and dosing protocols vary by institution and patient acuity. Always verify current prescribing information, institutional safety guidelines, and clinical policies before administration.
