Medicine & USMLE


Sympathomimetics and Sympatholytics (Old)
  1. Dopamine
  2. Fenoldopam
  3. Dobutamine
  4. Epinephrine
  5. Norepinephrine
  6. Isoproterenol
  7. Midodrine
  8. Phenylephrine and Pseudoephedrine
  9. (Alpha) Methyldopa
  10. Clonidine (and Guanfacine)
  11. Tizanidine


Fenoldopam is a drug that selectively activates or agonizes D1 receptors. Given intravenously, these D1 receptor effects cause significant vasodilation of the renal, mesenteric, and splanchnic arterial beds. This vasodilation decreases systemic vascular resistance and decreases blood pressure, thereby treating hypertensive emergencies. Importantly, the vasodilation of renal blood vessels increases blood flow or perfusion to the kidneys, which is useful in treating renal insufficiency.

Key Points

  • Fenoldopam
    • Mechanism
      • Selective Dopamine D1 agonist
        • FenolDOPAM is a DOPAMine derivative
        • No effect on alpha- or beta-adrenergic receptors, unlike other dopamine derivatives
        • Vasodilation (renal, mesenteric, coronary vessels)
          • D1 signalling activates adenylyl cyclase, increasing cAMP, which eventually causes smooth muscle relaxation
      • Must be given IV
        • Rapid onset of less than 10 minutes
        • Short half-life of 5 minutes
    • Clinical Use
      • Hypertensive emergency
        • Vasodilation reduces systemic vascular resistance, decreasing BP
          • Think: removing thumb from garden hose removes resistance, which reduces pressure of contents inside
      • Increases renal perfusion
        • Increased natriuresis and diuresis especially helpful for patients with renal insufficiency
        • Only available agent that improves renal perfusion while lowering blood pressure.
    • Adverse Effects
      • Hypotension
      • Reflex Tachycardia