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# Norepinephrine
## Overview
Norepinephrine is a potent catecholamine with primary alpha-1 adrenergic agonist activity (vasoconstriction) and secondary beta-1 adrenergic agonist activity (inotropic effect). It is the first-line vasopressor for septic and vasodilatory shock.
## Primary Indications
* Acute hypotensive states (e.g., septic shock, cardiogenic shock).
* Adjunct in the treatment of cardiac arrest (less common).
## Adult Dosing
* **Initial:** 0.05–0.5 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate to achieve target mean arterial pressure (MAP), often >65 mmHg.
* **Maximum:** No standardized physiologic maximum, but clinical doses often range up to 1–3 mcg/kg/min in refractory shock at major centers.
## Pediatric Dosing
* **Initial:** 0.05–0.1 mcg/kg/min continuous IV infusion.
* **Titration:** Titrate by 0.05–0.2 mcg/kg/min every 5–15 minutes based on hemodynamic response.
* **Maximum:** Typically 1–2 mcg/kg/min; consult local institutional protocols for specific ceilings.
## Dose Adjustments
* **Renal/Hepatic:** No formal dose adjustments required, but monitor closely for accumulation and tissue perfusion.
* **Tapering:** Must be tapered gradually to prevent rebound hypotension.
## Contraindications
* Hypersensitivity to norepinephrine or sulfite sensitivity.
* Hypotension due to uncorrected blood volume deficit (except as an emergency measure to maintain coronary/cerebral perfusion).
## Adverse Effects
* **Cardiovascular:** Hypertension, arrhythmias (bradycardia or tachycardia), myocardial ischemia, peripheral ischemia.
* **Extravasation:** Severe tissue necrosis and sloughing (treat with phentolamine infiltration if occurs).
* **Systemic:** Headache, anxiety, respiratory difficulty.
## Key Drug Interactions
* **MAO Inhibitors / TCAs:** May produce severe, prolonged hypertensive crises.
* **Beta-Blockers:** May lead to excessive alpha-mediated vasoconstriction (unopposed alpha stimulation) and severe hypertension/bradycardia.
* **Cyclopropane/Halogenated Hydrocarbons:** May sensitize the myocardium to catecholamines, increasing arrhythmia risk.
## Monitoring
* **Continuous:** Arterial line recommended for precise MAP monitoring and repeated blood draws.
* **Hemodynamics:** Heart rate, MAP, central venous pressure (CVP).
* **Perfusion:** Urine output, capillary refill, serum lactate levels.
* **Safety:** Site assessment every 30–60 minutes for signs of extravasation.
## Clinical Pearls
* **Administration:** Ideally administered via a central venous catheter to reduce the risk of extravasation and potential digital/limb necrosis.
* **Compatibility:** Ensure IV compatibility; use large veins if peripheral administration is absolutely necessary (short-term, low-concentration).
* **Fluid Status:** Vasopressors are not a substitute for effective volume resuscitation; ensure patient is adequately fluid-resuscitated before or during initiation.
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*Disclaimer: This information is for educational purposes only and does not supersede local institutional protocols. Always consult the most current prescribing information and verified hospital guidelines before administering medication.*
