Epinephrine

Summary

Epinephrine is a catecholamine that causes vasoconstriction, bronchodilation, and an increased heart rate. It is the drug of choice for treating airway closures and hypotension in anaphylaxis and is also part of the ACLS protocol for cardiac arrest. Epinephrine is usually given intramuscularly, and people with a history of severe allergic reactions should always carry an Epi-Pen.

Key Points

• Mechanism
  • Catecholamine
    • Stimulates alpha and beta adrenergic receptors
  • Bronchodilation
    • Stimulation of beta-2 receptors relaxes bronchial smooth muscle to cause airway dilation
  • Vasoconstriction
    • Stimulation of alpha-1 receptors increases blood pressure
  • Increased Heart Rate
    • Stimulation of beta-1 receptors increases heart rate
  • Clinical Use
    • Anaphylactic shock
      • Drug of choice; dilates airways and constricts systemic vasculature to restore normal blood pressure
      • Usually given IM
      • Can be repeated every 5-15 min if no response
      • Patients with a history of severe allergic reaction should always carry an EpiPen
    • Cardiac arrest
      • Used in ACLS algorithm, believed to improve return of circulation and perfusion
    • Bronchodilation also used to treat
      • Severe asthma attacks
      • Acute bronchospasm (COPD)
      • Croup (laryngotracheitis)
    • Bradycardia
      • Increases heart rate
    • May be combined with local anesthetics to reduce local bleeding by reducing blood flow and reduce anesthetic extravasation
  • Side Effects and Adverse Reactions
    • Cardiac distress
      • Dysrhythmias
      • Angina
      • Tachycardia
      • Hypertension
        • Concurrent use with MAOI may lead to hypertensive crisis
    • Excitability, anxiety, restlessness
    • Mydriasis (pupil dilation)
    • Hyperglycemia