P latelets play a key role in patients with an acute coronary syndrome, particularly in the early phases of the disease.1,2 Activated platelets release thromboxane A 2 (TXA 2 ), adenosine diphosphate (ADP), adenosine triphosphate, and thrombin, stimulating platelet activation and aggregation processes.3 Antiplatelet therapy is the cornerstone of treatment for patients with coronary artery disease. 4 Currently, the combination of aspirin, an irreversible inhibitor of cyclooxygenase and a P2Y 12 -ADP receptor inhibitor, is the antiplatelet treatment of choice in patients with acute coronary syndrome, where a fast and strong platelet inhibition is needed. 5,6 Clopidogrel, the most worldwide used P2Y 12 -ADP receptor antagonist, presents some limitations, such as high interand intraindividual variability or slow onset of action, despite loading dose (LD), which has been related with an increase of cardiovascular events. [7][8][9] This finding has been overcome with new ADP-antagonists, like prasugrel or ticagrelor.
10,11However, evidence is lacked about achieving faster and stronger cyclooxygenase inhibition. In fact, current guidelines of management of acute coronary syndrome only recommend LD of oral enteric-coated aspirin (162-325 mg) and intravenous use only when oral ingestion is not possible. 5,6 Lysine acetylsalicylate (LA) is a soluble salt that, shortly after being administered, is converted into acetylsalicylic acid, which is metabolized in the liver to salicylic acid (active form).12,13 LA presents potent antiplatelet compound with fewer gastrointestinal adverse effects than aspirin and has the unique property of being able to be administered both orally and intravenous.14 Some studies have compared aspirin with LA in both healthy volunteers and patients with stable Background-Prasugrel and ticagrelor, new P2Y 12 -adenosine diphosphate receptor antagonists, are associated with greater pharmacodynamic inhibition and reduction of cardiovascular events compared with clopidogrel in patients with an acute coronary syndrome. However, evidence is lacking about the effects of achieving faster and stronger cyclooxygenase inhibition with intravenous lysine acetylsalicylate (LA) compared with oral aspirin on prasugrel-inhibited platelets. Methods and Results-This was a prospective, randomized, single-center, open, 2-period crossover platelet function study conducted in 30 healthy volunteers. Subjects were randomly assigned to receive a loading dose of intravenous LA 450 mg plus oral prasugrel 60 mg or loading dose of aspirin 300 mg plus prasugrel 60 mg orally in a crossover fashion after a 2-week washout period between treatments. Platelet function was evaluated at baseline, 30 minutes, 1 h, 4 h, and 24 h using light transmission aggregometry and vasodilator-stimulated phosphoprotein phosphorylation. The primary end point of the study, inhibition of platelet aggregation after arachidonic acid 1.5 mmol/L at 30 minutes, was significantly higher in subjects treated with LA compared with aspirin: 85.3% versus 44.3%, res...