Norepinephrine

Norepinephrine (Levophed®)

Class:
  • Alpha adrenergic agonist (stimulates α1 and α2 receptors)
  • Beta adrenergic agonist (stimulates β1 receptors)
Actions: Stimulates sympathetic nervous system:

 

  • Vasoconstriction of peripheral arteries (α1 stimulation)
  • Increases systemic vascular resistance (  SVR)
  • Slight increase in heart rate (β1 stimulation) (positive inotropic)
  • Increase in contractility in low doses (< 2mcg/min)
Indications:
  • Shock secondary to peripheral vasodilation (neurogenic shock, septic shock)
  • Severe cardiogenic shock with hemodynamically significant hypotension (< 70 mm Hg systolic BP) and low SVR
Pharmacokinetics:
  • Onset: rapid
  • Duration:  1-2 minutes after discontinuation
Adverse Effects:
  • Tremors, hypertension, palpitations, reflex bradycardia
  • Headache, convulsions
  • Blurred vision, photophobia
  • Extravasation results in tissue necrosis.
Signs of Toxicity:
  • Hepatic or renal necrosis (elevated liver enzymes, BUN, or serum creatinine)
  • Cerebral hemorrhage (severe headache)
  • Hypertension
Contraindications:
  • Hypovolemic shock unless fluid resuscitation has already been established
  • Peripheral or mesenteric vascular thrombosis
  • Safety during pregnancy or lactation not established (Category D).
Dosages & Routes:
  • IV infusion:  0.5 – 1 mcg/min titrated to blood pressure up to maximum (30 mcg/min)
Nursing Implications:
  • Drug Interactions:  1) Alpha & beta blockers antagonize vasopressor effect; 2) Ergot alkaloids, furazolidone, guanethidine, methyl-dopa, and tricyclic antidepressants potentiate vasopressor effects; 3) Halothane and cyclopropane increase risk of dysrhythmias.
  • Drug Incompatibilities:  aminophyline, amobarbital, whole blood, cephapirin, chlorothiazide, chlorpheniramine, pentobarbital, phenobarbital, phenytoin, secobarbital, sodium bicarbonate, streptomycin, insulin, thiopental.
  • Monitor blood pressure and apical pulse continously during norepinephrine therapy.
  • Cardiac monitor should be used on patients receiving norepinephrine IV infusions.
  • Defibrillator and resuscitation cart should be close by during infusion.
  • Titrate infusion rate to maintain systolic BP at 80 – 100 mg Hg.
  • Assess patient frequently for headache, chest pain, or other signs of toxicity.
  • Do not mix other medications in IV line with norepinephrine drip.
  • Extravasation of norepinephrine may cause tissue necrosis to skin.  Therefore, monitor IV site every hour.  Have phentolamine (Regitine®) close to the bedside of the patient.

References:

American Heart Association. (2006). Handbook of Emergency Cardiac Care (p. 60). Salem, MA: AHA.

Dirks, J.L. (2010) Cardiovascular therapeutic management.  In L.D. Urden, K.M. Stacy, & M.E. Lough's (Eds.) Critical care nursing: Diagnosis and management (6th ed., pp. 545-547).  St. Louis: Mosby Elsevier.

Lehne, R.A. (2010). Pharmacology for nursing care (7th ed., pp. 152-157).  St. Louis: Saunders Elsevier.

Wilson, B.A., Shannon, M.T., Shields, K.M., & Stang, C.L. (2007).  Prentice Hall Nurse's Drug Guide 2007 (pp. 1178-1180).  Upper Saddle River, NJ: Pearson Prentice Hall.

 

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