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# Norepinephrine (Noradrenaline)
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 adrenergic activity (vasoconstriction) and moderate beta-1 adrenergic activity (inotropy). It is the first-line vasopressor for most forms of shock.
## Primary Indications
* Distributive shock (septic, neurogenic).
* Hypotension refractory to fluid resuscitation.
* Adjunctive therapy for cardiac arrest.
## Adult Dosing
* **Initial:** 0.05–0.1 mcg/kg/min (or 5–10 mcg/min flat rate) via central line.
* **Titration:** Titrate by 0.05–0.2 mcg/kg/min every 3–5 minutes to reach target Mean Arterial Pressure (MAP), typically ≥65 mmHg.
* **Maintenance/Common Range:** 0.01–3 mcg/kg/min.
* **Max dose:** No formal maximum; however, escalating doses reflect refractory shock requiring adjunctive agents (e.g., vasopressin).
## Pediatric Dosing
* **Initial:** 0.05–0.1 mcg/kg/min.
* **Titration:** Titrate by 0.05–0.1 mcg/kg/min every 5–10 minutes.
* **Maintenance/Common Range:** 0.05–2 mcg/kg/min.
* **Note:** Local institutional protocols and current PALS/pediatric ICU guidelines must be consulted.
## Dose Adjustments
* No specific renally or hepatically adjusted dosing exists; however, dose reductions may be needed in patients with high sensitivity to catecholamines or severe preexisting cardiovascular disease.
* Taper dose gradually to avoid rebound hypotension.
## Contraindications
* Hypersensitivity to norepinephrine or sulfites.
* Hypovolemic shock (must correct intravascular volume before initiation).
* Peripheral vascular thrombosis/ischaemia.
## Adverse Effects
* **Cardiovascular:** Arrhythmias, bradycardia (reflex), ischemia (myocardial/mesenteric/peripheral).
* **Local:** Extravasation can lead to severe tissue necrosis (due to intense alpha-1 vasoconstriction).
* **Metabolic:** Hyperglycemia, lactic acidosis (at high doses).
## Key Drug Interactions
* **MAO Inhibitors / TCAs:** May result in severe, prolonged, or dangerous hypertension.
* **Beta-blockers:** May cause unopposed alpha-adrenergic vasoconstriction and severe hypertension/bradycardia.
* **General Anesthetics (e.g., Halothane):** May sensitize the myocardium to arrhythmias.
## Monitoring
* **Continuous ECG:** Monitor for tachycardia or new-onset arrhythmias.
* **Blood Pressure:** Arterial line preferred for accurate, continuous measurement.
* **Tissue Perfusion:** Monitor urine output, peripheral skin temperature, and capillary refill time.
* **Access Site:** Inspect IV site frequently for signs of infiltration.
## Clinical Pearls
* **Extravasation Management:** If infiltration occurs, stop infusion immediately. Administer **phentolamine** (alpha-antagonist) subcutaneously in the affected area (5–10 mg in 10 mL saline) to prevent tissue necrosis.
* **Preferred Access:** Central venous catheter is strongly preferred; peripheral administration is acceptable in emergencies *if* the largest bore catheter is used in a proximal, large vein, but with high vigilance for extravasation.
* **Efficacy:** Studies suggest earlier initiation of norepinephrine in septic shock (vs. waiting for fluid resuscitation to complete) improves outcomes.
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**Educational Disclaimer:** This information is for educational purposes only. Dosing protocols vary significantly by institution and patient status. Always verify current prescribing information, institutional guidelines, and regional protocols before medication administration.
