rivaroxaban and cangrelor

Acute coronary syndrome (ACS) encompasses acute myocardial infarction (MI) and unstable angina. Activation of platelets and coagulation cascade plays a central role in the development of ACS. Over the past decade, there have been substantial improvements in the strategies for secondary prevention of ACS, including the development of more potent oral antiplatelet agents such as prasugrel and ticagrelor. However, therapies with even better efficacy and safety profiles and more rapid onset and offset of action would be desirable.. This review discusses the advantages and disadvantages of the currently available antithrombotic agents and describes the findings from recent clinical trials of three novel agents; cangrelor (an intravenous P2Y12 receptor antagonist), vorapaxar (protease-activated receptor-1 inhibitor) and rivaroxaban (an oral factor Xa inhibitor).. Cangrelor appears more promising than clopidogrel when a very rapid onset and reversal of antiplatelet effect is needed. Vorapaxar in addition to standard oral antiplatelet therapy was effective in patients with prior MI, but was not safe in patients with a prior stroke. Low dose rivaroxaban decreased cardiovascular events and mortality in patients post-ACS compared to placebo, although bleeding was increased.

Topics: Acute Coronary Syndrome; Adenosine Monophosphate; Fibrinolytic Agents; Humans; Lactones; Morpholines; Platelet Aggregation Inhibitors; Pyridines; Rivaroxaban; Thiophenes

Because novel direct acting anticoagulants are being tested in the secondary prevention of cardiovascular events, we assessed potential effects of a direct acting antagonist of Factor Xa on platelet function. Blood from patients with known coronary artery disease who were treated with aspirin but no other antithrombotic agent was spiked in vitro with rivaroxaban alone or in combination with a direct acting P2Y12 antagonist (cangrelor). To limit cofounding effects of anticoagulants and to enable interaction between coagulation factors, blood was anticoagulated only with a specific inhibitor of Factor XIIa, corn trypsin inhibitor. Polymerization of fibrin was prevented with the peptide GPRP. Activation of platelets was determined with the use of flow cytometry in response to lipidated tissue factor, thrombin, the collagen mimetic convulxin, and adenosine diphosphate (ADP). Rivaroxaban inhibited the activation of platelets induced by tissue factor and to a lesser extent activation induced by thrombin, effects that were accentuated when combined with cangrelor. Rivaroxaban did not attenuate convulxin-induced activation of platelets; however, a limited but consistent attenuation of ADP-induced platelet activation was seen with blood anticoagulated with rivaroxaban. Effects of rivaroxaban on ADP-induced platelet activation were not mediated by thrombin, tissue factor, or platelet-leukocyte aggregation. In conclusion, rivaroxaban attenuated in vitro the activation of platelets mediated by thrombin. In light of the pivotal role of thrombin in platelet activation after rupture of an atherosclerotic plaque, rivaroxaban should attenuate platelet activation in vivo, an effect that is accentuated by combination with a P2Y12 antagonist.

Topics: Adenosine Monophosphate; Aged; Anticoagulants; Aspirin; Blood Platelets; Coronary Artery Disease; Crotalid Venoms; Factor Xa; Factor Xa Inhibitors; Female; Humans; Lectins, C-Type; Male; Middle Aged; Morpholines; Plant Proteins; Platelet Activation; Platelet Aggregation Inhibitors; Platelet Function Tests; Purinergic P2Y Receptor Antagonists; Receptors, Purinergic P2Y12; Rivaroxaban; Thiophenes