Nor%252525252525252525252525252525252525252525252520epinephrine

# Norepinephrine ## Overview Norepinephrine (Levophed) is a vasopressor that acts primarily on alpha-1 adrenergic receptors, causing vasoconstriction, and to a lesser extent on beta-1 adrenergic receptors, increasing heart rate and contractility. ## Primary Indications * Severe hypotension and shock (e.g., septic shock, cardiogenic shock) refractory to initial fluid resuscitation. * Cardiogenic shock. * Septic shock. ## Adult Dosing * **Initial Dose:** 0.01 to 0.02 mcg/kg/min IV infusion. * **Titration:** Titrate to achieve target mean arterial pressure (MAP) of 65 mmHg or higher, or to restore adequate tissue perfusion. Doses can be increased by 0.01 to 0.02 mcg/kg/min every 5-10 minutes as needed. * **Maximum Dose:** Generally considered 0.1 mcg/kg/min, though higher doses may be used in refractory shock under expert guidance. Typical maximum infusion rates can reach up to 30 mcg/min (equivalent to approximately 0.3-0.4 mcg/kg/min for a 70-80 kg patient). ## Pediatric Dosing * **Initial Dose:** 0.05 to 0.1 mcg/kg/min IV infusion. * **Titration:** Titrate to achieve target MAP equal to or greater than gestational age plus 2 years (in mmHg) for infants and children up to 10 years, or 70 mmHg for older children. Doses can be increased by 0.05 to 0.1 mcg/kg/min every 5-10 minutes. * **Maximum Dose:** Generally 1 mcg/kg/min. ## Dose Adjustments * No specific dose adjustments for renal or hepatic impairment are established due to its rapid metabolism. Dosing is primarily guided by hemodynamic response and patient tolerance. ## Contraindications * Hypersensitivity to norepinephrine. * Concurrent use of monoamine oxidase inhibitors (MAOIs) or use within 14 days of MAOI therapy (risk of severe hypertensive crisis). * Concurrent use of linezolid or other oxazolidinone antibiotics (risk of severe hypertensive crisis). * Use in patients with mesenteric or peripheral vascular thrombosis, as it may increase ischemic necrosis and extend infarct size. ## Adverse Effects * **Common:** Hypertension, bradycardia (reflex), tachycardia, arrhythmias, peripheral ischemia, headache, anxiety, tremor, dizziness, skin necrosis (extravasation). * **Less Common:** Pulmonary edema, decreased cardiac output. ## Key Drug Interactions * **MAOIs, Linezolid, other Oxazolidinones:** Increased risk of hypertensive crisis. * **Tricyclic Antidepressants (TCAs), Guanethidine, Maprotiline, Methylphenidate:** Potentiated pressor effects, increased risk of hypertension. * **Alpha-adrenergic Blockers (e.g., prazosin, terazosin):** May decrease pressor effect. * **Beta-adrenergic Blockers:** May antagonize beta-1 effects, potentially leading to unopposed alpha-receptor stimulation and worsening hypertension. * **Anesthetics (e.g., cyclopropane, halothane):** Increased myocardial irritability, risk of arrhythmias. * **Ergot Alkaloids:** Potentiated vasoconstriction. * **Dobutamine:** May blunt the pressor response if used concurrently. ## Monitoring * **Hemodynamics:** Continuous ECG, blood pressure (arterial line preferred), central venous pressure (CVP), pulmonary artery pressures (if available). * **Perfusion:** Urine output, capillary refill, mental status, peripheral pulses, skin temperature. * **Infusion Site:** Frequent checks for signs of extravasation. * **Electrolytes and Acid-Base Status:** Especially in critically ill patients. ## Clinical Pearls * Norepinephrine is a potent vasoconstrictor and requires careful titration. * Always administer via a central venous catheter or arterial line to minimize risk of extravasation. * If extravasation occurs, immediately stop infusion, aspirate drug from the line, and infiltrate the area with phentolamine mesylate. * Use the lowest effective dose for the shortest duration necessary. * Gradually taper norepinephrine to avoid sudden drops in blood pressure. * Consider alternative vasopressors or inotropes if hypotension persists despite adequate norepinephrine dosing. * Its short half-life requires continuous infusion. *** *Disclaimer: This information is intended for educational purposes only and does not constitute medical advice. Always consult the most current prescribing information and refer to institutional protocols for definitive patient care decisions.*