1035

Introduction: There are limited pharmacokinetic data and no clinical data on how to transition patients from clopidogrel to prasugrel, a more potent thienopyridine, as patients receiving a clopidogrel within the previous 5 days were excluded from the major clinical trial supporting prasugrel for the treatment of acute coronary syndromes (ACS) treated with percutaneous intervention (PCI). Adequate platelet inhibition is important in treating ACS to prevent thrombotic complications. The purpose of this study is to describe the safety of a loading dose of prasugrel in patients switching from clopidogrel for the treatment of ACS. Hypothesis: The hypothesis was that loading a patient with prasugrel after receiving clopidogrel is safe when treating ACS. Methods: Patients treated with a loading dose of prasugrel for ACS between Jan 2010 and July 2012 were retrospectively identified. Patients were included if they received clopidogrel within the previous 48 hours. Primary outcome was the development of TIMI major bleeding at 30 days or during index hospitalization. Results: 28 patients met inclusion criteria; 19 patients (68%) received a clopidogrel loading dose (300-600mg) prior to prasugrel loading, 9 (32%) were on maintenance clopidogrel therapy (75mg). Baseline characteristics were: average age 53 years (range 32-73 yrs); 86% male; 75% Caucasian; 32% diabetes; 57% admission diagnosis of STEMI; 86% required ICU admission after PCI; average weight 88.6 kg (range 66-108 kg). Of the patients who received a clopidogrel load prior to prasugrel, 58% received 300mg and prasugrel was started 19 hrs later on average; patients not receiving a clopidogrel load had prasugrel started 10 hrs after the last dose of clopidogrel. All but 1 patient were treated with PCI; 67% received a drug eluting stent (DES). The patient not treated with PCI had recent DES placed, developed an allergic reaction to clopidogrel and subsequently developed stent thrombosis; the patient underwent thrombus aspiration without PCI and was switched to prasugrel. No patient developed TIMI major bleeding. Overt bleeding was not observed in any patient but 1 patient required transfusion of 2 units of packed red blood cells. No patient died during the hospital stay and the average length of stay was 3.6 days. Conclusions: Loading a patient with prasugrel even if the patient has already received clopidogrel appears to have an adequate safety profile. This could be a favorable strategy in high risk patients when more potent antiplatelet therapy may be preferred. Larger studies would be needed to verify these safety results given the potent nature of prasugrel.