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## Norepinephrine (Levophed) ### Overview Norepinephrine is a potent alpha-1 adrenergic agonist and a weaker beta-1 adrenergic agonist. It causes vasoconstriction, leading to increased systemic vascular resistance and blood pressure. ### Primary Indications * Treatment of shock, particularly septic shock and cardiogenic shock, to maintain adequate blood pressure. * Adjunct treatment of severe hypotension and circulatory collapse. ### Adult Dosing * **Initial Dose:** 0.01 to 0.02 mcg/kg/min IV infusion. * **Maintenance Dose:** Titrate infusion rate to achieve target mean arterial pressure (MAP), typically a systolic blood pressure of 80-110 mmHg or a MAP of 65 mmHg. Doses may range from 0.01 to 0.3 mcg/kg/min. * **Maximum Dose:** Generally not to exceed 0.3 mcg/kg/min, though higher doses may be used in refractory hypotension under expert guidance. Dosing is highly individualized and dependent on patient response. ### Pediatric Dosing * **Initial Dose:** 0.05 to 0.1 mcg/kg/min IV infusion. * **Maintenance Dose:** Titrate to target MAP. Doses may range from 0.05 to 2 mcg/kg/min. * **Note:** Pediatric dosing is complex and often guided by local protocols and expert consultation. ### Dose Adjustments * **Renal Impairment:** No specific dose adjustment is typically recommended, but close monitoring is essential due to potential for altered pharmacokinetics. * **Hepatic Impairment:** No specific dose adjustment is typically recommended, but close monitoring is essential. ### Contraindications * Hypersensitivity to norepinephrine. * Hypotensive anesthesia (e.g., spinal and epidural). * In cases where vasopressors may cause undue tissue ischemia (e.g., patients with peripheral vascular thrombosis). ### Adverse Effects * **Cardiovascular:** Arrhythmias (tachycardia, bradycardia, ventricular), hypertension, peripheral ischemia, extravasation leading to tissue necrosis, angina. * **Central Nervous System:** Headache, anxiety, dizziness. * **Other:** Dyspnea, sweating. ### Key Drug Interactions * **MAO Inhibitors and Tricyclic Antidepressants:** May potentiate the pressor effect; avoid concurrent use or use with extreme caution and significantly reduced initial doses. * **Anesthetic Agents (e.g., Halogenated anesthetics):** May