PDE3 Inhibitors (Cilostazol, Dipyridamole)

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Key Points

  • PDE3 Inhibitors
    • Drug Names
      • Cilostazol
      • Dipyridamole
    • Mechanism
      • Inhibits PDE3
        • Increases cAMP by inhibiting its breakdown by PDE3
          • In platelets, inhibits platelet aggregation
          • In vascular smooth muscle, induces vasodilation
    • Clinical Use
      • Peripheral arterial disease (PAD)
        • Inhibition of clot formation by platelets and vasodilation both help reduce claudication, improving symptoms
      • Cardiac stress test (dipyridamole)
        • Dipyridamole artificially dilates all coronary vessels
        • However, partially occluded vessels are already maximally dilated at baseline, serving to shunt more blood to ischemic tissue to compensate for the occlusion
        • Therefore, when dipyridamole dilates all other vessels, this impairs the compensatory shunting of blood by diverting blood away from the obstructed vessels, therefore provoking ischemia.
        • This test may be used to assess the degree of vessel occlusion in patients
      • Prevention of stroke
        • Usually combined with aspirin
    • Adverse Effects
      • Hypotension
        • Due to vasodilating effects in vascular smooth muscle
        • Reduced vascular resistance causes reduction in blood pressure
      • Flushing
      • Nausea, abdominal pain
      • Headache