Acta Chirurgica Scandinavica 543: 65–72, 1988īarrowcliffe TW, Merton RE, Havercroft SJ, Thunberg L, Lindahl U, et al. Pharmacokinetics of low molecular weight heparins. Seminars in Thrombosis and Hemostasis 11: 316–317, 1985īara L, Samama M. Increased anti-Xa bioavailability for a low molecular weight heparin (PK 10169) compared with unfractionated heparin. Proceedings of the National Academy of Sciences of the United States of America 81: 1030–1034, 1984īara L, Billaud E, Kher A, Samama M. Evaluation of critical groups required for the binding of heparin to antithrombin. Thrombosis Research 52: 517–527, 1988Ītha DH, Stephens AW, Rosenberg RD. Heparin clearance and ex vivo recovery in newborn piglets and adult pigs. Thrombosis Research 56: 529–539, 1989Īndrew M, Ofosu F, Schmidt B, Brooker L, Hirsh J, et al. The comparison of the pharmacokinetics of a low molecular weight heparin in the newborn and adult pig. British Journal of Haematology 59: 103–108, 1985Īndrew M, Ofosu F, Brooker L, Buchanan MR. Placental transport of low molecular weight heparin in the pregnant sheep. Thrombosis Research 9: 575–583, 1976Īndrew M, Boneu B, Cade J, Cerskus AL, Hirsh J, et al. Anticoagulant properties of heparin fractionated by affinity chromatography on matrix-bound antithrombin III and by gel filtration. Both forms of heparin are useful antithrombotic agents however, the correlation between the antithrombotic effect and an in vitro laboratory test for either type still needs further clarification.Īndersson LO, Barrowcliffe TW, Holmer E, Johnson EA, Sims GEC. For this reason, the concave-convex pattern is not seen with low molecular weight preparations. The nonsaturable elimination mechanism is renal and is the primary route of elimination for low molecular weight heparins. The disposition curve for unfractionated heparin has a unique concave-convex shape which is the result of combined saturable and nonsaturable elimination mechanisms. A short distribution phase is seen which is thought to correspond to endothelial cell binding and internalisation. After either subcutaneous or intravenous injection heparin is distributed primarily within the intravascular space. In order to accomplish this a total of 18 to 22 monosaccharide units is necessary including a specific pentasaccharide binding site for antithrombin III. Heparin produces its antithrombotic effect by binding to antithrombin III and this complex then binds to thrombin. Unfractionated heparin is a heterogenous mixture of polysaccharide chains of varying length resulting in a range of molecular weights from 3000 to 30 000D while low molecular weight heparin ranges from 3000 to 6000D. It is available for exogenous administration both as unfractionated and low molecular weight heparin. An endogenous glycosaminoglycan, heparin is found largely in the liver, lung and intestine. Heparin was discovered approximately 75 years ago and has been used extensively for the last 50 years to treat thromboembolic disorders.
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