NOREPINEPHRINE BITARTRATE

NOREPINEPHRINE BITARTRATE
(nor-ep-i-nef'rin)
Levarterenol, Levophed, Noradrenaline
Classifications: alpha- and beta-adrenergic agonist; vasoconstrictor;
Therapeutic: vasoconstrictor
; inotropic
Prototype: Epinephrine
Pregnancy Category: C

Availability

1 mg/mL injection

Action

Direct-acting sympathomimetic amine identical to body catecholamine norepinephrine. Acts directly and predominantly on alpha-adrenergic receptors; little action on beta receptors except in heart (beta1 receptors). Vasoconstriction and cardiac stimulation; also powerful constrictor action on resistance and capacitance blood vessels.

Therapeutic Effect

Peripheral vasoconstriction and moderate inotropic stimulation of heart result in increased systolic and diastolic blood pressure, myocardial oxygenation, coronary artery blood flow, and workload of the heart.

Uses

To restore BP in certain acute hypotensive states such as shock, sympathectomy, pheochromocytomectomy, spinal anesthesia, poliomyelitis, MI, septicemia, blood transfusion, and drug reactions. Also as adjunct in treatment of cardiac arrest.

Contraindications

Use as sole therapy in hypovolemic states, except as temporary emergency measure; mesenteric or peripheral vascular thrombosis; profound hypoxia or hypercarbia; use during cyclopropane or halothane anesthesia; hypertension; hyperthyroidism; MAOI therapy; pregnancy (category C).

Cautious Use

Severe heart disease; older adult patients; within 14 d of MAOI therapy; patients receiving tricyclic antidepressants; lactation.

Route & Dosage

Hypotension
Adult: IV Initial 0.5–1 mcg/min, titrate to response; usual range 8–30 mcg/min
Child: IV 0.05–0.1 mcg/kg/min; titrate to response (max: 1–2 mcg/kg/min)

Administration

Intravenous

PREPARE: IV Infusion: Dilute a 4 mL ampule in 1000 mL of D5W or D5/NS. More concentrated solutions (e.g., 4 mg in 500 mL to yield 8 mcg/mL) may be used based on fluid requirements. Do not use solution if discoloration or precipitate is present. Protect from light.  

ADMINISTER: IV Infusion: Initial rate of infusion is 2–3 mL/min (8–12 mcg/min), then titrated to maintain BP, usually 0.5–1 mL/min (2–4 mcg/min). An infusion pump is used. Usually give at the slowest rate possible required to maintain BP. Constantly monitor flow rate. Check infusion site frequently and immediately report any evidence of extravasation: blanching along course of infused vein (may occur without obvious extravasation), cold, hard swelling around injection site. Antidote for extravasation ischemia: Phentolamine, 5–10 mg in 10–15 mL NS injection, is infiltrated throughout affected area (using syringe with fine hypodermic needle) as soon as possible. If therapy is to be prolonged, change infusion sites at intervals to allow effect of local vasoconstriction to subside. Avoid abrupt withdrawal; when therapy is discontinued, infusion rate is slowed gradually.  

INCOMPATIBILITIES Solution/additive: Aminophylline, amobarbital, ampicillin, whole blood, cephapirin, chlorothiazide, chlorpheniramine, diazepam, pentobarbital, phenobarbital, phenytoin, secobarbital, sodium bicarbonate, sodium iodide, streptomycin, thiopental, warfarin. Y-site: Insulin, thiopental.

Adverse Effects (≥1%)

Body as a Whole: Restlessness, anxiety, tremors, dizziness, weakness, insomnia, pallor, plasma volume depletion, edema, hemorrhage, intestinal, hepatic, or renal necrosis, retrosternal and pharyngeal pain, profuse sweating. CV: Palpitation, hypertension, reflex bradycardia, fatal arrhythmias (large doses), severe hypertension. GI: Vomiting. Metabolic: Hyperglycemia. CNS: Headache, violent headache, cerebral hemorrhage, convulsions. Respiratory: Respiratory difficulty. Skin: Tissue necrosis at injection site (with extravasation). Special Senses: Blurred vision, photophobia.

Interactions

Drug: alpha and beta blockers antagonize pressor effects; ergot alkaloids, furazolidone, guanethidine, methyldopa, tricyclic antidepressants may potentiate pressor effects; halothane, cyclopropane increase risk of arrhythmias.

Pharmacokinetics

Onset: Very rapid. Duration: 1–2 min after infusion. Distribution: Localizes in sympathetic nerve endings; crosses placenta. Metabolism: In liver and other tissues by catecholamine o-methyl transferase and monoamine oxidase. Elimination: In urine.

Nursing Implications

Assessment & Drug Effects

  • Monitor constantly while patient is receiving norepinephrine. Take baseline BP and pulse before start of therapy, then q2min from initiation of drug until stabilization occurs at desired level, then every 5 min during drug administration.
  • Adjust flow rate to maintain BP at low normal (usually 80–100 mm Hg systolic) in normotensive patients. In previously hypertensive patients, systolic is generally maintained no higher than 40 mm Hg below preexisting systolic level.
  • Observe carefully and record mental status (index of cerebral circulation), skin temperature of extremities, and color (especially of earlobes, lips, nail beds) in addition to vital signs.
  • Monitor I&O. Urinary retention and kidney shutdown are possibilities, especially in hypovolemic patients. Urinary output is a sensitive indicator of the degree of renal perfusion. Report decrease in urinary output or change in I&O ratio.
  • Be alert to patient's complaints of headache, vomiting, palpitation, arrhythmias, chest pain, photophobia, and blurred vision as possible symptoms of overdosage. Reflex bradycardia may occur as a result of rise in BP.
  • Continue to monitor vital signs and observe patient closely after cessation of therapy for clinical sign of circulatory inadequacy.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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