USMLE

Ephedrine / Phenylephrine

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Respiratory Drugs
  1. Cromolyn
  2. Montelukast
  3. Guaifenesin
  4. Ephedrine / Phenylephrine
  5. Theophylline
  6. Acetylcysteine

Summary

Ephedrine, pseudoephedrine, and phenylephrine are medications that have different effects depending on their route of administration. When given nasally or orally, they can be used to treat congestion. When used as a decongestant, a potential side effect is rebound nasal congestion, so patients should not take these medications for more than 3-5 days and should taper off the drug slowly.  When given through an IV, these drugs act systemically as vasopressors, where they constrict the blood vessels to increase blood pressure. Regardless of the route of administration, side effects to look out for include CNS stimulation, which can present as insomnia, restlessness, agitation, or nervousness. These drugs can also cause uncontrolled hypertension, and should not be given concurrently with other drugs that cause hypertension, or to patients who already have high blood pressure and other cardiovascular conditions.

Key Points

  • Decongestants / Vasopressors
    • Key Drugs
      • Ephedrine
      • Pseudoephedrine (Sudafed)
      • Phenylephrine
      • Oxymetazoline
    • Mechanism
      • Stimulate alpha-1 adrenergic receptors to cause vasoconstriction
        • When given systemically this will raise blood pressure
        • When given locally in the nose this reduces nasal secretions (less blood flow → less fluid secretions)
    • Clinical Use
      • Decongestant
        • When given through nasal drops/spray or as an ingredient in oral liquid cold medicine
        • Nasal congestion
        • Rhinitis, sinusitis
        • The common cold
        • Patients with hypertension should not take cold medicine that contains phenylephrine or pseudoephedrine because of their vasoconstrictive properties.
      • Vasopressors
        • When given through IV
        • Causes vasoconstriction to raise blood pressure in patients with severe hypotension
    • Side Effects and Adverse Reactions
      • Rebound nasal congestion (nasal drops/spray only)
        • Advise patients to use no longer than 3-5 days
        • Taper use
      • CNS Stimulation
        • Agitation, nervousness, excitability, restlessness
      • Hypertension
        • Avoid in patients with hypertension, dysrhythmias, coronary artery disease, and other cardiovascular conditions
        • Do not give concurrently with MAOIs