Antithrombotic activity and its relationship to in vitro anticoagulant effects.
Antithrombotic activities of low molecular weight heparins (LMWHs) in a venous stasis thrombosis model, when compared to unfractionated heparin (UFH), correlated better with anti-IIa activities and inhibition of thrombin generation than with anti-Xa activities. The relative antithrombotic potencies of LMWHs were closer to inhibitory activity in thrombin generation with platelet-poor plasma than platelet-rich plasma. Comparing activities in intrinsic and extrinsic systems, higher concentrations of heparins were required in vitro to inhibit intrinsic thrombin generation than extrinsic thrombin production; however, higher doses were required to prevent in vivo thrombotic events initiated via the extrinsic pathway.
National Institute for Biological Standards and Control, Potters Bar, Herts, UK.
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E
Gray
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Padilla
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Barrowcliffe
D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D065427:Factor Xa Inhibitors; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D006493:Heparin / Q000494:pharmacology / Q000627:therapeutic use; D006495:Heparin, Low-Molecular-Weight / Q000494:pharmacology* / Q000627:therapeutic use; D011516:Prothrombin / Q000037:antagonists & inhibitors; D011817:Rabbits; D013917:Thrombin / Q000096:biosynthesis; D013924:Thrombophlebitis / Q000517:prevention & control
D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D005343:Fibrinolytic Agents; D006495:Heparin, Low-Molecular-Weight; D011516:Prothrombin; C025337:Factor IIa; D006493:Heparin; D013917:Thrombin