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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 septic shock and other forms of distributive shock.
## Primary Indications
* Acute hypotension (septic, cardiogenic, or distributive shock).
* Adjunct treatment during cardiac arrest (rare, after other measures).
## Adult Dosing
* **Initial:** 0.05 to 0.1 mcg/kg/min or 2 to 4 mcg/min via continuous IV infusion.
* **Titration:** Titrate to achieve target Mean Arterial Pressure (MAP) (usually ≥65 mmHg). Usual effective range is 0.05 to 0.5 mcg/kg/min.
* **Maximum:** Doses exceeding 1–3 mcg/kg/min may be utilized in refractory shock, but risk of severe peripheral ischemia increases significantly.
## Pediatric Dosing
* **Initial:** 0.05 to 0.1 mcg/kg/min IV continuous infusion.
* **Titration:** Titrate by 0.05 mcg/kg/min increments every 5–15 minutes based on blood pressure response.
* **Maximum:** Typically up to 1–2 mcg/kg/min.
## Dose Adjustments
* **Renal/Hepatic:** No specific dosage adjustments provided in labeling; titration is based solely on hemodynamic response.
* **Local Protocol:** Titration increments, target MAP, and maximum doses are strictly governed by institutional ICU protocols. Always refer to your facility's specific guidelines.
## Contraindications
* Hypersensitivity to norepinephrine or sulfite-containing products.
* Hypotension due to uncorrected blood volume deficit (except as an emergency temporary measure).
## Adverse Effects
* **Cardiovascular:** Hypertension, arrhythmias (bradycardia or tachycardia), myocardial ischemia.
* **Peripheral:** Tissue necrosis/sloughing upon extravasation (most critical risk).
* **Metabolic:** Lactic acidosis (with prolonged, high-dose therapy).
## Key Drug Interactions
* **MAO Inhibitors/TCAs:** Can cause severe, prolonged hypertension.
* **Beta-blockers:** May result in unopposed alpha-adrenergic vasoconstriction (severe hypertension and reflex bradycardia).
* **Cyclopropane/Halogenated Hydrocarbon Anesthetics:** Increases myocardial irritability and risk of arrhythmias.
## Monitoring
* **Continuous arterial blood pressure monitoring:** Highly recommended (gold standard).
* **Heart rate and rhythm:** ECG monitoring required.
* **Peripheral perfusion:** Monitor distal extremities for signs of ischemia or cyanosis.
* **Infusion site:** Central venous access is preferred to prevent extravasation necrosis.
## Clinical Pearls
* **Extravasation Management:** If extravasation occurs, stop the infusion immediately and infiltrate the area with **phentolamine** (alpha-adrenergic antagonist) to prevent tissue necrosis.
* **Correction of Hypovolemia:** Norepinephrine should not be used as a substitute for fluid resuscitation; ensure adequate intravascular volume replenishment throughout therapy.
* **Dosing Units:** Ensure strict adherence to mcg/kg/min vs. mcg/min as programmed in the infusion pump to prevent medication errors.
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*Disclaimer: This information is for educational purposes only. Clinical practice varies by institution. Always verify dosages, contraindications, and compatibility with current prescribing information, institutional protocols, and your clinical supervisor.*
