Comparison of P2Y12 receptor inhibition by clopidogrel and prasugrel in patients undergoing percutaneous coronary intervention.

Dual antiplatelet treatment (DAPT) with aspirin and clopidogrel is vital after percutaneous coronary intervention (PCI). Clopidogrel and prasugrel act on P2Y12 platelet surface receptors. Both these P2Y12 inhibitors are pro-drugs and depend on cytochrome system of the liver for their conversion to active metabolite. There is growing concern regarding suboptimal response in platelet inhibition by clopidogrel. Verify Now system got approval by Federal Drug Administration, USA, for assessing platelet function as its result is almost comparable to gold standard Light Transmission Aggregometry (LTA). There are no data on the prevalence of clopidogrel resistance in Bangladeshi population. Prasugrel, as an antiplatelet drug, is a newer introduction in this country. This study will show light on the efficacy of these drugs on our population especially in patients who undergo PCI where DAPT is mandatory. A total 120 (60 diabetics) patients with Acute Coronary Syndrome (ACS), were alternatively given 600 mg clopidogrel loading dose (LD) followed by 75 mg maintenance dose (MD) daily or 60 mg LD of prasugrel followed by 10 mg MD daily. Five samples of blood were taken at different time intervals over a period of 2 weeks. Measurement of percent inhibition of P2Y12 was done by VerifyNow. Patients who showed less than 20% inhibition (clopidogrel resistant) at any stage were switched to prasugrel. The outcomes of clopidogrel, prasugrel and clopidogrel switched to prasugrel groups were then compared. Nearly half (46.7%) of the patients in the clopidogrel group was found resistant to the drug as opposed to none in the prasugrel group. No difference was found between diabetic and non-diabetic subjects with respect to drug resistance. Intracoronary blood samples showed high degree of platelet inhibition with prasugrel. There was a gradual decline of platelet inhibition over two weeks with prasugrel. Almost fifty percent of the population is clopidogrel resistant in our study. Prasugrel is a much more potent antiplatelet drug and should be preferred in patients undergoing PCI. Prasugrel may also show resistance over time.