title: Synergistic effect of a factor Xa inhibitor, TAK-442, and antiplatelet agents on whole blood coagulation and arterial thrombosis in rats.
abstract: BACKGROUND
  Activated platelets facilitate blood coagulation by providing factor V and a procoagulant surface for prothrombinase. Here, we investigated the potential synergy of a potent factor Xa/prothrombinase inhibitor, TAK-442, plus aspirin or clopidogrel in preventing arterial thrombosis and whole blood coagulation.
  
  
  METHODS
  Thrombus formation was initiated by FeCl(3)-induced rat carotid injury. Bleeding time was evaluated with the rat tail transection model. Whole blood coagulation was assessed by thromboelastographic examination (TEG) for which blood obtained from control, aspirin-, or clopidogrel-treated rats was transferred to a TEG analyzer containing, collagen or adenosine diphosphate (ADP), and TAK-442 or vehicle.
  
  
  RESULTS
  TAK-442 (3mg/kg, po), aspirin (100mg/kg, po) or clopidogrel (3mg/kg, po) alone had no significant effect on thrombus formation, whereas the combination of TAK-442 with aspirin and clopidogrel remarkably prolonged the time to thrombus formation without additional significant prolongation of bleeding time. TEG demonstrated that the onset of collagen-induced blood coagulation were slightly longer in aspirin-treated rats than control; however, when the blood from aspirin-treated rats was subsequently treated in vitro with 100 nM TAK-442, the onset of clotting was significantly prolonged. In contrast, only marginal prolongation was observed with TAK-442 treatment of blood from control animals. The onset time of ADP-induced blood coagulation was slightly longer in clopidogrel-treated rats compared with control, and it was further extended by TAK-442 treatment.
  
  
  CONCLUSIONS
  These results demonstrate that blood coagulation can be markedly delayed by the addition of TAK-442 to antiplatelets treatment which could contribute to synergistic antithrombotic efficacy in these settings.
authors.affiliation: Pharmacology Research Laboratories, Takeda Pharmaceutical Company Ltd., Osaka, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Konishi
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Hiroe
authors.forename: Masaki
authors.initials: M
authors.lastname: Kawamura
mesh_terms: D000818:Animals; D001241:Aspirin / Q000494:pharmacology / Q000627:therapeutic use*; D001777:Blood Coagulation / Q000187:drug effects*; D001780:Blood Coagulation Tests; D000077144:Clopidogrel; D004357:Drug Synergism; D065427:Factor Xa Inhibitors; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D011744:Pyrimidinones / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013450:Sulfones / Q000494:pharmacology / Q000627:therapeutic use*; D013927:Thrombosis / Q000188:drug therapy*; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: C553657:1-(1-(3-((6-chloronaphthalen-2-yl)sulfonyl)-2-hydroxypropanoyl)piperidin-4-yl)tetrahydropyrimidin-2(1H)-one; D065427:Factor Xa Inhibitors; D010975:Platelet Aggregation Inhibitors; D011744:Pyrimidinones; D013450:Sulfones; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin