Comparison of Prasugrel and Clopidogrel in Very Elderly and Non-Elderly Patients With Stable Coronary Artery Disease (GENERATIONS)

• Change in Vasodilator-associated Stimulated Phosphoprotein (VASP) From Baseline to 12 Days of Therapy [ Time Frame: Baseline, Day 12 ] [ Designated as safety issue: No ]
  Vasodilator-associated stimulated phosphoprotein (VASP) phosphorylation levels, expressed as the platelet reactivity index (PRI), reflect the degree of thienopyridine-mediated P2Y12 receptor inhibition. A lower PRI reflects stronger inhibition of P2Y12, whereas a higher PRI reflects weaker inhibition of P2Y12.
• Change in VerifyNow P2Y12 Reaction Units (PRU) From Baseline to 12 Days of Therapy [ Time Frame: Baseline, Day 12 ] [ Designated as safety issue: No ]
  The Accumetrics VerifyNow® P2Y12 assay measures platelet aggregation in whole blood and is reported in P2Y12 reaction units (PRU). PRU report the extent of P2Y12 receptor-mediated platelet aggregation calculated as a function of the rate and extent of platelet aggregation in the presence of adenosine phosphate ADP. A lower PRU reflects stronger inhibition of P2Y12, whereas a higher PRU reflects weaker inhibition of P2Y12.
• Active Metabolite Blood Levels to Drug Exposure as Measured by Pharmacokinetics (PK) Through 4 Hours After Dosing [ Time Frame: Baseline up to 4 hours post-dose ] [ Designated as safety issue: No ]
  A descriptive pharmacokinetic-pharmacodynamic (PK-PD) analysis comparing prasugrel and clopidogrel active metabolite exposures to MPA in response to 20 µM ADP (by LTA) was conducted as originally intended; however, the graphic output from that analysis is not possible here. Therefore, the PK portion is presented here as AUC and the PD portion is presented in Secondary Outcome Measure #5. AUC was calculated through the last scheduled sampling time of 4 hours [AUC (0-4)] or through the sampling time of the last quantifiable concentration prior to 4 hours. AUC values were denoted AUC(0-tlast) in both instances.
• Change From Baseline in Maximum Platelet Aggregation (MPA) as Measured by Light Transmission Aggregometry (LTA) From Baseline at Day 12 of Therapy [ Time Frame: Baseline, Day 12 ] [ Designated as safety issue: No ]
  Maximum Platelet Aggregation (MPA) to 20 μM ADP was assessed by light transmission aggregometry (LTA), an assay that measures platelet aggregation by determining the amount of light transmitted through a cuvette containing the platelet-rich plasma stimulated with a platelet activator, such as ADP, relative to platelet-poor plasma (100% light transmittance). A lower MPA reflects stronger platelet inhibition, whereas a higher MPA reflects weaker inhibition.

• Change in vasodilator-associated stimulated phosphoprotein (VASP) from baseline to 12 days of therapy [ Time Frame: Baseline, 12 days ] [ Designated as safety issue: No ]
• Change in VerifyNow P2Y12 reaction units (PRU) from baseline to 12 days of therapy [ Time Frame: Baseline, 12 days ] [ Designated as safety issue: No ]
• Change in MPA associated with exposure to drug active metabolite blood levels as measured by pharmacokinetics from baseline to 12 days of therapy [ Time Frame: Baseline, 12 days ] [ Designated as safety issue: No ]
• Change in maximum platelet aggregation (MPA)as measured by light transmission aggregometry (LTA) from baseline to 12 days of therapy [ Time Frame: Baseline, 12 days ] [ Designated as safety issue: No ]

The 5-milligram (mg) maintenance dose (MD) of prasugrel in very elderly patients with coronary artery disease produces a pharmacodynamic response within the same therapeutic range as 10-mg MD in non-elderly patients.

• Drug: prasugrel
  administered orally, daily for 12 days
  Other Names:

  • Efient
  • Effient
  • LY640315
  • CS747
• Drug: clopidogrel
  Administered orally, daily for 12 days

• Experimental: 5 milligrams (mg) prasugrel
  Intervention: Drug: prasugrel
• Active Comparator: 10 mg prasugrel
  Intervention: Drug: prasugrel
• Active Comparator: 75 mg clopidogrel
  Intervention: Drug: clopidogrel

Inclusion Criteria:

• Participants (Either: at least 45 years of age, but less than 65 years of age OR 75 years of age or older) with a history of stable coronary artery disease who are not currently indicated for treatment with a thienopyridine (that is, prasugrel, clopidogrel, or ticlopidine)
• Provision of written informed consent
• Body weight greater than or equal to 60 kilograms (kg)
• For women of child-bearing potential only (that is, women who are not surgically or chemically sterilised and who are between menarche and 1 year post menopause), test negative for pregnancy (based on a urine or serum pregnancy test to be performed before randomisation) and agree to use a reliable method of birth control during the study

Exclusion Criteria:

• Unstable coronary artery disease
• Myocardial Infarction (MI) within the previous 30 days
• Percutaneous Coronary Intervention (PCI) or Coronary Artery Bypass Graft Surgery (CABG) within the previous 90 days
• History of refractory ventricular arrhythmias within the last 6 months; an implanted defibrillator device; congestive heart failure within 6 months prior to screening; major surgery, or severe trauma, fracture or organ biopsy within 3 months prior to enrollment
• Any planned surgical procedure or any coronary revascularisation (surgical or percutaneous) planned within 60 days following randomisation
• Any known contraindication to treatment with an antiplatelet agent
• Significant hypertension at the time of screening or randomisation
• Clinically significant out-of-range values for platelet count or haemoglobin at screening, in the investigator's opinion, or results of clinical laboratory tests at the time of screening that are judged to be clinically significant for the study population, as determined by the investigator
• Prior history or presence of significant bleeding disorders, abnormal bleeding tendency, or personal history of coagulation or bleeding disorders
• Prior history or clinical suspicion of cerebral vascular malformations, intracranial neoplasm, Transient Ischemic Attack (TIA) or stroke
• Prior history of thrombocytopenia or thrombocytosis
• Use of antiplatelet agents (besides aspirin) within 10 days prior to screening; the use (or planned use) of heparin, oral anticoagulants, or fibrinolytic agents within 30 days of screening; or participants receiving daily treatment with nonsteroidal anti-inflammatory drugs (NSAIDS) or cyclooxygenase-2 (COX-2) inhibitors that cannot be discontinued for the duration of the study