PDE3 Inhibitors (Cilostazol, Dipyridamole)

Summary

PDE3 inhibitors, including cilostazol and dipyridamole, stop platelets from aggregating together and cause vasodilation. These drugs are used for symptom management in patients with peripheral artery disease and during cardiac stress tests. Watch out for hypotension as a potential side effect.  

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