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Differential thrombin generation inhibition by branded and generic low molecular weight heparins (LMWHs) as studied using a fluorescence substrate based kinetic method
Author(s) -
Adiguzal Cafer,
Litinas Evangelos,
Cunanan Josephine,
Hoppensteadt Debra,
Fareed Jawed
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.569.3
Subject(s) - thrombin , chemistry , substrate (aquarium) , coagulation , fluorescence , fondaparinux , cleavage (geology) , thrombin generation , multiplex , biophysics , chromatography , reagent , biochemistry , platelet , materials science , organic chemistry , immunology , biology , bioinformatics , venous thromboembolism , psychiatry , thrombosis , ecology , fracture (geology) , composite material , psychology , quantum mechanics , medicine , physics , surgery
Thrombin generation reflects the overall activity of the coagulation cascade. Conventional clot‐based methods are not useful for monitoring LMWHs or fondaparinux. In order to compare the relative inhibitory effects of branded enoxaparin (Lovenox) and several generic LMWHs (Lupenox, Loparin, Dripanina, Dilutol, Cutenox and Clenox), we used a thrombin generation assay (Technothrombin® TGA) based on cleavage of a fluorescent substrate. Each LMWH was supplemented to plasma at concentrations of 2.5 to 10µg/ml. Plasma samples were activated by reagents containing various concentrations of tissue factor (TF) and negatively charged phospholipids and the change in fluorescence was measured. The change in fluorescence is proportional to the amount of thrombin generated. Each LMWH concentration dependently inhibited thrombin generation. With the lower concentration of TF (TGA RC‐high), almost complete inhibition of thrombin generation was noted with 10µg/ml LMWH. The IC50s for the LMWHs ranged from 2.5 to 5µg/ml. Only partial inhibition of the thrombin generation was noted at a LMWH concentration of 10 µg/ml when a higher concentration of TF (TGA RD) was used. Each LMWH showed a distinct inhibitory profile. These studies showed that LMWHs can be differentiated based on their ability to inhibit thrombin generation. Furthermore, the TGA RC‐high is more suitable for the monitoring of LMWHs in contrast to the TGA RD.