Summary

Midodrine is a selective activator or agonist of alpha-1 adrenergic receptors. Alpha-1 activity then induces systemic vasoconstriction, which is useful in the treatment of orthostatic hypotension.

Key Points

• Midodrine
  • Mechanism of Action
    • Alpha-1 Agonist
      • Arterial Vasoconstriction → Increased TPR
      • Venous Vasoconstriction → Increased Venous Return → Increased Cardiac Output
  • Clinical Use
    • Autonomic Insufficiency
    • Orthostatic Hypotension
      • Alpha 1-mediated venous vasoconstriction helps maintain venous return despite the effects of gravity from standing up
  • Adverse Effects
    • May exacerbate supine hypertension (can be extrapolated from its clinical use)