Platelet ADP Receptor Antagonist

Aka: Platelet ADP Receptor Antagonist, Adenosine Receptor Antagonist, P2Y12 Receptor Antagonist, P2Y12 Inhibitor, P2Y Receptor Antagonist, P2Y Receptor Inhibitor, Thienopyridine, Thiophene

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II. Indications: Prevention of Thrombotic Events

  1. Cerebrovascular Accident Prevention
  2. Coronary Artery Disease Prevention (especially if Aspirin Allergy)
  3. Post-ST Elevation MI (with or without reperfusion)

III. Contraindications

  1. Active Bleeding

IV. Mechanism: Thienopyridine Class

  1. Inhibits Platelet signal transduction
  2. Inhibits Platelet aggregation
  3. Reversibly binds Adenosine Diphosphate (ADP) P2Y12-Class Receptors
    1. Inhibits G Protein
    2. Inhibits Adenyl Cyclase

V. Medications

  1. Cangrelor (Kengreal)
    1. Limited to intravenous use during PCI if other P2Y12 Inhibitors have not been given
  2. Clopidogrel (Plavix)
    1. Generic as of May 2012
    2. Less GI Bleeding than Aspirin or Prasugrel
      1. Option if GI Bleeding occurs with Aspirin
      2. Switch to Plavix does not prevent recurrent GI Bleed
        1. GI Bleed occurs in 8% of those switched to Plavix
        2. Consider adding PPI to Aspirin instead of Plavix
    3. Dosing
      1. Load: 300 mg once
      2. Maintenance: 75 mg orally daily
  3. Prasugrel (Effient)
    1. More effective than Plavix in cardiovascular event reduction
    2. Higher risk of bleeding than Plavix in age >75 years, weight <60 kg, CVA history
    3. Avoid in prior Cerebrovascular Accident (CVA) or Transient Ischemic Attack (TIA)
    4. Typically initiated in the catheter lab
      1. Avoid initiating in emergency department due to bleeding risk
    5. References
      1. Wiviott (2007) N Engl J Med 357(20):2001-15 [PubMed]
    6. Dosing for impending Percutaneous Coronary Intervention (PCI)
      1. Load: 60 mg once
      2. Maintenance: 10 mg orally daily
  4. Ticagrelor (Brilinta)
    1. Recommended by ACA (2016) over Clopidogrel in Acute Coronary Syndrome and stenting
      1. Ticagrelor prevents more adverse CV events than Clopidogrel
      2. Majority of cardiovascular benefit is within first few weeks after Acute Coronary Syndrome
    2. Adverse Effects and disadvantages
      1. Similar bleeding risk to Clopidogrel
      2. Dyspnea occurs with Brilinta use for 1 in 27 patients
      3. Requires twice daily dosing
    3. Dosing
      1. Load: 180 mg once
      2. Maintenance: 90 mg orally twice daily
      3. No dosing adjustment needed in renal and mild hepatic Impairment
      4. Use caution in moderate liver disease and avoid in severe liver disease
  5. Ticlopidine (Ticlid)
    1. Associated with serious adverse effects (Neutropenia, Thrombotic Thrombocytopenic Purpura)

VI. Drug Interactions: General

  1. Morphine (and presumed other Opioids)
    1. Morphine decreased (35%) and delayed (2 hours) Ticagrelor absorption
    2. Appears to impact all P2Y12 Inhibitor
    3. May affect acute STEMI management
    4. Kubica (2016) Int J Cardiol 215:201-8 [PubMed]

VII. Management: Reversal

  1. Platelet Transfusion 2 units (12 pack)
  2. Consider Desmopressin (DDAVP) 0.3 mcg/kg (expert opinion)
  3. Consider Recombinant activated Clotting Factor VII (rFVIIa) 30-90 mcg/kg (expert opinion)

VIII. References

  1. Filler and Lovecchio (2017) Crit Dec Emerg Med 31(7): 24
  2. Switaj (2017) Am Fam Physician 95(4): 232-40 [PubMed]

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