USMLE

ADP Receptor Inhibitors

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Heme Pharm
  1. Warfarin
  2. Heparin
  3. Low Molecular Weight Heparins (LMWH)
  4. Direct Thrombin Inhibitors (Argatroban, Dabigatran, Bivalirudin)
  5. Thrombolytics (tPA, Streptokinase, Urokinase)
  6. ADP Receptor Inhibitors
  7. PDE3 Inhibitors (Cilostazol, Dipyridamole)
  8. Glycoprotein IIb/IIIa Inhibitors
  9. Factor Xa Inhibitors (Apixaban, Rivaroxaban, Edoxaban)

Summary

ADP receptor inhibitors are a class of drugs that includes ticagrelor, ticlopidine, and clopidogrel. ADP receptor inhibitors work to prevent platelet aggregation by blocking the ADP receptor.  As platelet aggregation into a platelet plug is the first step in blood clot formation, ADP receptor inhibitors are clinically used to prevent blood clot formation, especially in patients at risk for stroke or myocardial infarction due to a previous stroke or prior stent placement. As with any drug that prevents blood clotting, patients taking ADP receptor inhibitors are at increased risk for bleeding.

Key Points

  • ADP Receptor Inhibitors
    • Drug Names
      • Clopidogrel
      • Ticagrelor
      • Ticlopidine
      • Prasugrel
    • Mechanism
      • Irreversibly antagonize ADP receptors (P2Y12) on platelets
        • Prevents platelet aggregation
        • Platelets normally release ADP from granules when activated
          • ADP binds to ADP receptors to induce expression of GpIIb/IIIa.
          • Fibrinogen binds to gpIIb/IIIA enables formation of the platelet plug (primary hemostasis)
    • Clinical Use
      • Prevention of cardiovascular clots (MI/ACS, stroke)
        • Dual antiplatelet therapy (with aspirin)
        • Treatment for acute coronary syndrome (NSTEMI or STEMI)
        • Prevention of thrombosis after stenting
        • Lowers risk of recurrent strokes
        • Treatment of peripheral artery disease
    • Adverse Effects
      • Bleeding
        • Obvious effect of platelet inhibition
      • Neutropenia (ticlopidine)
      • Thrombotic thrombocytopenic purpura (ticlopidine)