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# Norepinephrine
## Overview
Norepinephrine is a potent sympathomimetic agent with strong alpha-adrenergic activity and moderate beta-1 adrenergic activity. It is the first-line vasopressor for septic shock.
## Primary Indications
* Acute hypotensive states (e.g., septic shock, cardiogenic shock).
* Cardiac arrest (less common than epinephrine).
## Adult Dosing
* **Initial Infusion:** 0.05 to 0.1 mcg/kg/min (or 5–30 mcg/min flat rate per local protocol).
* **Titration:** Titrate to maintain target mean arterial pressure (e.g., 65 mmHg) in increments of 0.05–0.1 mcg/kg/min every 3–5 minutes.
* **Typical Maintenance Range:** 0.01 to 3 mcg/kg/min.
* **Maximum:** No strict maximum; however, doses >1–2 mcg/kg/min are associated with severe tissue ischemia and refractory shock.
## Pediatric Dosing
* **Infusion:** Start at 0.05–0.1 mcg/kg/min.
* **Titration:** Titrate by 0.05 mcg/kg/min to achieve age-appropriate blood pressure.
* **Typical Maximum:** Generally up to 1 mcg/kg/min, though clinical judgment in persistent shock may necessitate higher doses in specialized settings (PICU).
## Dose Adjustments
* **Renal/Hepatic:** No standardized adjustments required; clinical response dictates dosing.
* **Central access:** Highly recommended; peripheral administration carries high risk of extravasation injury.
## Contraindications
* Hypotension due to uncorrected blood volume deficit (restore volume first).
* Hypersensitivity to norepinephrine or sulfites.
* Thrombosis (mesenteric or peripheral vascular).
## Adverse Effects
* **Common:** Hypertension, headache, anxiety.
* **Serious:** Tissue necrosis/gangrene (if extravasated), limb ischemia, arrhythmias (bradycardia or tachycardia), mesenteric ischemia, hyperglycemia.
## Key Drug Interactions
* **MAO Inhibitors / TCAs:** May significantly potentiate pressor effects, leading to hypertensive crisis.
* **Beta-blockers:** May antagonize cardiac effects or lead to unopposed alpha-mediated vasoconstriction.
* **Halogenated Anesthetics:** May increase myocardial sensitivity to catecholamines.
## Monitoring
* **Continuous:** Blood pressure (ideally arterial line), heart rate, ECG rhythm, and oxygen saturation.
* **Frequent:** Perfusion assessment (capillary refill, mental status, urine output, skin color) and peripheral IV site inspection (if central line not present).
## Clinical Pearls
* **Extravasation Management:** If extravasation occurs, stop the infusion immediately and infiltrate the area with phentolamine (alpha-adrenergic antagonist) to prevent necrosis.
* **Volume Status:** Norepinephrine is ineffective in a hypovolemic patient; aggressive fluid resuscitation should precede or accompany initiation.
* **Peripheral Administration:** Safe for short-term use in large-bore, proximal veins if central access is delayed; verify local facility policy regarding concentration limits (e.g., 16 mcg/mL or lower).
* **Drug Stability:** Protect from light; use immediately after dilution.
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*Disclaimer: This information is for educational purposes only. Clinical protocols for concentration, titration, and peripheral administration vary by institution. Always verify dosages and compatibility against current institutional guidelines and the product package insert before prescribing or administering medication.*
