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)