Nor%25252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252525252520epinephrine

# Norepinephrine ## Overview Norepinephrine is a potent endogenous catecholamine and vasopressor that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction and increasing systemic vascular resistance. It also has beta-1 adrenergic receptor activity, leading to increased cardiac contractility and heart rate. ## Primary Indications * Treatment of hypotension and shock, particularly septic shock and cardiogenic shock, in conjunction with other therapies. ## Adult Dosing * **Intravenous infusion:** Typically initiated at **2 to 4 mcg/min** (0.01 to 0.02 mcg/kg/min). * **Titration:** Doses are titrated upwards based on patient response (mean arterial pressure [MAP] goal, typically ≥65 mmHg) or other hemodynamic parameters. * **Maximum dose:** Doses can range from **0.1 to 1.5 mcg/kg/min** (approximately 7 to 105 mcg/min for a 70 kg patient), though higher doses may be used in select cases under close monitoring. The precise maximum depends on clinical scenario and response. ## Pediatric Dosing * **Intravenous infusion:** Typically initiated at **0.05 to 0.1 mcg/kg/min**. * **Titration:** Doses are titrated upwards based on patient response, typically to a target MAP greater than or equal to gestational age plus 2 in preterm neonates, or a target systolic blood pressure of the 50th percentile for age or greater in older children. * **Maximum dose:** Doses can range up to **1 mcg/kg/min**. ## Dose Adjustments * **Renal Impairment:** No specific dose adjustment is typically recommended, but caution and close monitoring are advised due to potential accumulation. * **Hepatic Impairment:** No specific dose adjustment is typically recommended, but caution and close monitoring are advised. ## Contraindications * Hypersensitivity to norepinephrine. * Concurrent use with cyclopropane and halogenated hydrocarbon anesthetics (risk of severe hypertension and arrhythmias). ## Adverse Effects * **Common:** Hypertension, bradycardia (reflex), peripheral ischemia, anxiety, headache, dizziness, tremor, arrhythmias, tissue necrosis (if extravasation occurs). * **Severe:** Severe hypertension, arrhythmias, myocardial infarction, cerebrovascular accident, pulmonary edema, gangrene. ## Key Drug Interactions * **Monoamine Oxidase Inhibitors (MAOIs):** Potentiate hypertensive crisis. Norepinephrine should be used with extreme caution or avoided in patients taking MAOIs; an interval of at least 14 days is generally recommended. * **Tricyclic Antidepressants (TCAs):** May potentiate the pressor response. * **Alpha-adrenergic Blockers (e.g., prazosin, terazosin):** May antagonize the pressor effects. * **Beta-adrenergic Blockers:** May blunt the cardiac effects and potentially lead to unopposed alpha-adrenergic stimulation, causing severe hypertension. * **Ergot Alkaloids and Oxytocin:** May cause severe hypertension. * **Guanethidine and similar adrenergic neuron blocking agents:** May reduce the pressor effect. * **Anesthetics (volatile, e.g., halothane, isoflurane):** Increase myocardial irritability and risk of arrhythmias. ## Monitoring * **Hemodynamic parameters:** Continuous arterial blood pressure monitoring is essential. Heart rate, cardiac output, and central venous pressure (if monitored) should also be assessed. * **Infusion site:** Monitor closely for signs of extravasation and tissue ischemia. * **Urine output:** Assess for adequate perfusion. * **Mental status:** Monitor for signs of anxiety or confusion. * **Laboratory tests:** Electrolytes, renal function, and liver function as clinically indicated. ## Clinical Pearls * Norepinephrine is typically administered via a central venous catheter to minimize the risk of extravasation and local tissue damage. * If extravasation occurs, the infusion should be stopped immediately, and the affected area should be infiltrated with **phentolamine**. * It is crucial to avoid abrupt discontinuation; taper the infusion gradually to prevent hypotension. * Norepinephrine should be protected from light. * The drug is typically diluted in dextrose-containing solutions (e.g., D5W) or normal saline, but consult institutional guidelines for preferred diluents. *** **Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional protocols before administering any medication. Patient-specific factors can significantly influence drug selection and dosing.