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# Norepinephrine
## Overview
Norepinephrine (Levophed) is a potent sympathomimetic amine that acts primarily as an alpha-adrenergic agonist, causing vasoconstriction and increasing systemic vascular resistance. It also has some beta-1 adrenergic activity, leading to an increase in myocardial contractility.
## Primary Indications
* Treatment of severe hypotension and shock (e.g., septic shock, cardiogenic shock) that does not respond to fluid resuscitation.
## Adult Dosing
* **Usual starting dose:** 0.01 to 0.02 mcg/kg/min intravenously.
* **Titration:** May be increased in increments of 0.01 to 0.02 mcg/kg/min every 5-15 minutes to achieve and maintain the desired mean arterial pressure (MAP).
* **Maximum dose:** Typically 0.2 mcg/kg/min, but higher doses may be used cautiously under specialist guidance. Local protocols often dictate specific titration ranges and maximums.
## Pediatric Dosing
* **Usual starting dose:** 0.05 to 0.1 mcg/kg/min intravenously.
* **Titration:** May be increased in increments of 0.05 to 0.1 mcg/kg/min every 5-15 minutes.
* **Maximum dose:** Generally up to 1 mcg/kg/min, but higher doses may be used cautiously. Dosing is highly dependent on patient condition and local protocols.
## Dose Adjustments
* **Renal Impairment:** No specific dose adjustment guidelines. Use with caution; renal dose adjustment is often guided by clinical response.
* **Hepatic Impairment:** No specific dose adjustment guidelines. Use with caution; hepatic dose adjustment is often guided by clinical response.
## Contraindications
* Hypersensitivity to norepinephrine.
* Avoid use in patients with mesenteric or peripheral vascular thrombosis unless it is the only option to save their life.
## Adverse Effects
* **Cardiovascular:** Arrhythmias (especially ventricular), tachycardia, bradycardia (reflex), hypertension, peripheral ischemia/gangrene, chest pain, decreased cardiac output.
* **Local:** Extravasation can cause severe tissue necrosis; administer via a central venous catheter when possible.
* **Other:** Headache, anxiety, dyspnea, nausea, vomiting, tremor.
## Key Drug Interactions
* **Monoamine Oxidase Inhibitors (MAOIs) and Tricyclic Antidepressants (TCAs):** Potentiate hypertensive effects. Discontinue MAOIs at least 14 days prior to norepinephrine administration.
* **Anesthetics (e.g., halogenated anesthetics):** May increase myocardial irritability and risk of arrhythmias.
* **Alpha and Beta Blockers:** May antagonize effects.
* **Vasoconstrictors (e.g., vasopressin):** Additive vasoconstrictive effects, increased risk of ischemia.
## Monitoring
* Continuous electrocardiogram (ECG) and blood pressure monitoring.
* Central venous pressure (CVP) or pulmonary artery catheter (PAC) data if available.
* Urine output.
* Peripheral circulation (e.g., skin color, temperature, capillary refill).
* Infusion site for signs of extravasation.
* Serum lactate and other indicators of perfusion.
## Clinical Pearls
* Norepinephrine is typically infused via a central venous catheter to minimize the risk of extravasation and tissue necrosis.
* If extravasation occurs, stop the infusion immediately, do not flush the line, and administer phentolamine locally.
* Norepinephrine is a potent drug and requires careful titration to achieve therapeutic goals while minimizing adverse effects.
* Consider the underlying cause of hypotension and address it concurrently with vasopressor support.
This information is for educational purposes and does not replace current prescribing information. Always verify with the most up-to-date drug product labeling and consult with a healthcare professional.
