Type 2 diabetics with CAD experience greater antiplatelet activity with prasugrel compared to clopidogrel

Results from a new study showed patients with type 2 diabetes who also had coronary artery disease (CAD) experienced greater antiplatelet activity with the investigational antiplatelet drug prasugrel compared to Plavix(R) (clopidogrel). Patients who received a 60 mg loading dose and 10 mg maintenance dose of prasugrel achieved significantly greater platelet inhibition compared with a 600 mg loading dose and 150 mg maintenance dose of Plavix. These data were presented at the American Heart Association 2009 Scientific Sessions in Orlando, Florida.

The OPTIMUS-3 (Third Optimising anti-Platelet Therapy In Diabetes MellitUS) study, which evaluated 35 patients with type 2 diabetes who also had CAD and were taking aspirin, showed that within four hours, the level of platelet inhibition as measured using the VerifyNow(R) P2Y12 Test with a 60 mg loading dose of prasugrel was higher than observed with a 600 mg loading dose of clopidogrel (89.3 per cent vs. 27.7 per cent inhibition of platelet activation (IPA), respectively; P(less than)0.0001). In addition, one hour after the loading dose, patients who received prasugrel had 50 per cent IPA compared with 13 per cent in patients who received clopidogrel (P(less than)0.0001). The level of platelet inhibition achieved for each drug at four hours was nearly unchanged over the following 24 hours. A 600 mg loading dose of clopidogrel is not currently approved for use by Health Canada.

"Not only are people with diabetes more prone to coronary artery disease, but they also have higher platelet reactivity than people without diabetes, and as a result, may not respond as well to antiplatelet therapy," said Dr. Shaun Goodman, Co-Chair of the Canadian Heart Research Centre. "The results of this study are encouraging, as there is a clear need for antiplatelet therapy that provides greater platelet inhibition for patients with diabetes than the current standard of care."

The OPTIMUS-3 study also looked at the maintenance doses of prasugrel and clopidogrel. After seven days, results showed that a 10 mg maintenance dose of prasugrel achieved greater platelet inhibition than a 150 mg maintenance dose of clopidogrel (62 per cent vs. 44 per cent IPA, respectively; P(less than)0.0001).

Dr. Goodman noted that, "these findings support our previously published finding that prasugrel was superior to clopidogrel in reducing the chances of having a second heart attack in more than 3,000 patients with diabetes participating in the Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition With Prasugrel-Thrombolysis in Myocardial 38 (TRITON-TIMI 38)."