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# Norepinephrine (levophed)
## Overview
Norepinephrine is a potent catecholamine with primarily 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
* First-line treatment for septic shock.
* Treatment of hypotension refractory to fluid resuscitation in other forms of shock (e.g., cardiogenic, distributive).
## Adult Dosing
* **Initial Infusion:** 0.05–0.1 mcg/kg/min or 5–10 mcg/min via continuous IV infusion.
* **Titration:** Titrate to maintain target mean arterial pressure (MAP), typically 65 mmHg. Usual maintenance range is 0.01–3 mcg/kg/min.
* **Maximum:** No formal absolute maximum; however, clinical practice typically seeks to add secondary agents (e.g., vasopressin) if doses exceed 0.5–1 mcg/kg/min to minimize alpha-adrenergic toxicity.
## Pediatric Dosing
* **Initial Infusion:** 0.05–0.1 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate by 0.05 mcg/kg/min every 5–15 minutes as needed to achieve perfusion targets.
* **Maintenance:** Generally up to 1–2 mcg/kg/min.
## Dose Adjustments
* **Renal/Hepatic:** No formal dose adjustments required; however, monitor closely for tissue hypoperfusion.
* **Dosing Variation:** Exact titration protocols, starting rates, and concentration standards (e.g., 8 mg/250 mL or 32 mg/250 mL) vary significantly by institution. **Always verify local protocols.**
## Contraindications
* Hypersensitivity to norepinephrine.
* Hypovolemia (must be corrected prior to initiation whenever possible).
* Thrombosis (mesenteric or peripheral vascular) due to profound vasoconstriction risk.
## Adverse Effects
* **Cardiovascular:** Hypertension, bradycardia (reflexive), tachyarrhythmias, myocardial ischemia.
* **Local:** Extravasation can lead to severe tissue necrosis and sloughing.
* **Metabolic/Systemic:** Peripheral/visceral ischemia, metabolic acidosis.
## Key Drug Interactions
* **MAO Inhibitors/Antidepressants:** May cause severe, prolonged hypertension.
* **Beta-Blockers:** May result in unopposed alpha-adrenergic stimulation (excessive vasoconstriction).
* **General Anesthetics (e.g., Halothane/Cyclopropane):** Increased risk of ventricular arrhythmias.
## Monitoring
* **Hemodynamics:** Continuous blood pressure monitoring (preferably via arterial line) and heart rate.
* **Perfusion:** Urine output, capillary refill, skin temperature, and serum lactate levels.
* **Access Site:** Constant observation for signs of extravasation. If extravasation occurs, consider phentolamine infiltration.
## Clinical Pearls
* **Central Access:** Should be administered via a large-bore central venous catheter whenever possible. Peripheral administration is acceptable in emergencies for short durations through a large, proximal vein (e.g., antecubital) with frequent site checks.
* **First-line status:** Norepinephrine is currently preferred over dopamine in the management of septic shock due to a more favorable safety profile and lower incidence of arrhythmias.
* **Refractory Shock:** If vasopressor requirements remain high despite adequate titration, consider adding vasopressin (0.03–0.04 units/min) or epinephrine.
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**Educational Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Clinical practice may vary based on institutional protocols. Always verify current prescribing information, safety guidelines, and patient-specific contraindications with your facility’s clinical resources before prescribing or administering medication.
