• Ephedrine is a mixed adrenergic agonist that directly binds and activates alpha- and beta-adrenergic receptors as well as causing release of endogenously-stored norepinephrine from presynaptic terminals.
Mechanism of Action
  • Direct Adrenergic Activation
  • Indirect Adrenergic Activation
    • Ephedrine also results in release of stored norepinephrine from adrenergic neuron nerve terminals into the synaptic cleft, contributing to non-specific activation of the SNS.
Pharmacological Actions
  • Overview
    • Given its rather non-specific activation of the SNS, the pharmacological actions of ephedrine are rather predictable and include vasoconstriction, cardiac activation, and bronchodilation. Clinical use of ephedrine has fallen out of favor given its wide-ranging effects and its use has been replaced by more specific adrenergic agonists.
  • Cardiovascular Effects
    • Systemic vasoconstriction due to activation of alpha1 receptors, combined with enhancement of cardiac contractility and heart rate via beta1 receptors, produce increased systolic arterial pressure. At high doses use of ephedrine results in tachycardia and hypertension.
  • Respiratory Effects
  • Central Effects
    • Activation of central adrenergic neurons results in increased alertness and decreased fatigue. At high doses patients may experience insomnia.