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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine acting primarily on alpha-1 adrenergic receptors (vasoconstriction) and, to a lesser extent, beta-1 adrenergic receptors (inotropy). It is the first-line vasopressor for most types of shock.
## Primary Indications
* Acute hypotensive states (e.g., septic shock, cardiogenic shock).
* Adjunctive therapy for cardiac arrest (per ACLS protocols).
## Adult Dosing
* **Vasopressor titration:** Start infusion at 0.01 to 0.05 mcg/kg/min. Titrate to effect (typical MAP target ≥65 mmHg).
* **Typical titration range:** 0.05 to 0.5 mcg/kg/min.
* **Max dose:** No formal maximum dose exists; clinical response and end-organ perfusion dictate titration. Doses >1 mcg/kg/min are associated with significant vasoconstriction and tissue ischemia risk.
## Pediatric Dosing
* **Vasopressor infusion:** 0.05 to 0.1 mcg/kg/min, titrated to hemodynamic stability.
* **Max dose:** Often capped at 1–2 mcg/kg/min, though institutional protocols vary significantly based on patient stability.
## Dose Adjustments
* **Renal/Hepatic impairment:** No specific dose adjustments established; however, monitor closely for tissue hypoperfusion.
* **Underlying vascular disease:** Use caution and lower starting doses in patients with severe peripheral vascular disease.
## Contraindications
* Hypersensitivity to norepinephrine or bisulfites (present in some formulations).
* Hypotension due to uncorrected blood volume deficit (except as emergency support before fluid replacement is complete).
* Mesenteric or peripheral vascular thrombosis.
## Adverse Effects
* **Common:** Hypertension, headache, anxiety.
* **Serious:** Tissue necrosis/sloughing (if extravasation occurs), bradycardia (reflex), cardiac arrhythmias, mesenteric ischemia, peripheral ischemia.
## Key Drug Interactions
* **MAO inhibitors/Tricyclic antidepressants:** May result in severe, prolonged hypertension.
* **Beta-blockers:** May block beta-1 effects, leading to unopposed alpha-1 vasoconstriction and severe hypertension.
* **Cyclopropane or Halothane anesthesia:** Increased risk of ventricular arrhythmias.
## Monitoring
* **Hemodynamics:** Continuous blood pressure monitoring (preferably arterial line).
* **Perfusion:** Monitor urine output, serum lactate, and peripheral extremity perfusion.
* **Site:** Frequent checks for extravasation. Use a central venous catheter whenever possible.
## Clinical Pearls
* **Treatment of Extravasation:** If infiltration occurs, infiltrate the area immediately with 5–10 mg of phentolamine in 10–15 mL of saline.
* **Fluid First:** Norepinephrine is a vasopressor, not a volume expander. Ensure fluid resuscitation has been addressed prior to or during initiation.
* **Compatibility:** Administer through a large vein (central line preferred) to avoid necrosis.
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*Disclaimer: This information is for educational purposes and does not replace professional clinical judgment. Always verify dosages, contraindications, and compatibility with the most current institutional protocols and the official manufacturer package insert before prescribing or administering medication.*
