Studies in Man and Experimental Animals of a Low Molecular Weight Heparin Fraction

D P Thomas; R E Merton; W E Lewis; T W Barrowcliffe

doi:10.1055/s-0038-1650173

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 1981; 45(03): 214-218
DOI: 10.1055/s-0038-1650173

Original Article

Schattauer GmbH Stuttgart

Studies in Man and Experimental Animals of a Low Molecular Weight Heparin Fraction

Authors

D P Thomas

The National Institute for Biological Standards and Control, Holly Hill, London
R E Merton

^*The Glaxo Operations U. K. Limited, Westfield Road, Runcorn, Cheshire, U. K.
W E Lewis

The National Institute for Biological Standards and Control, Holly Hill, London
T W Barrowcliffe

The National Institute for Biological Standards and Control, Holly Hill, London

Abstract

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Summary

In vitro and in vivo studies were carried out on a commercially prepared low molecular weight heparin fraction. By APTT assay the fraction had a specific activity of half that of unfractionated mucosal heparin, yet retained full potency by anti-Xa assay (both clotting and chromogenic substrate). When administered intravenously to human volunteers, the anti-Xa/APTT ratio remained the same as it was in vitro. However, after subcutaneous injection, the ratio increased and anti-Xa activity could not be fully neutralized ex vivo by PF₄. The fraction was as effective as unfractionated heparin in preventing experimental serum-induced thrombosis, suggesting that a heparin fraction with high specific activity by anti-Factor Xa assay compared to APTT activity may be an effective drug for the prophylaxis of venous thrombosis.

Keywords

Heparin - Heparin fraction - Experimental venous thrombosis

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References

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