Anticoagulant and antithrombotic effects of heparin and low molecular weight heparin fragments in rabbits.
Heparin and heparin fragments of different molecular weight and with different anti-factor Xa/APTT activity ratios were studied with respect to their ability to inhibit thrombus formation in an animal model. It is concluded that: a) Neither anti-factor Xa nor the APTT activity alone is a good reflector of the antithrombotic activity. b) Anti-factor Xa active fragments must have a minimum molecular weight in order to elicit good antithrombotic activity. c) High affinity for antithrombin III is important for good antithrombotic activity. d) A heparin fragment of molecular weight 4 000 has the same antithrombotic activity as heparin but less effect on the clotting time.
D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects*; D005170:Factor X; D015951:Factor Xa; D005260:Female; D006493:Heparin / Q000032:analysis / Q000494:pharmacology*; D008297:Male; D008970:Molecular Weight; D010314:Partial Thromboplastin Time; D011817:Rabbits; D013927:Thrombosis / Q000517:prevention & control*
D005170:Factor X; D006493:Heparin; D015951:Factor Xa