Ecarin chromogenic assay--a new method for quantitative determination of direct thrombin inhibitors like hirudin.
A new sensitive and precise method for quantitative determination of direct thrombin inhibitors is described, the ecarin chromogenic assay (ECA). Ecarin is used as the specific prothrombin-activating principle. The cleavage of a chromogenic substrate by meizothrombin is inhibited in a concentration-dependent fashion by direct thrombin inhibitors. For the ECA, the linear measuring range is about 0.1-3.0 microg hirudin/ml plasma. Coefficients of variations between 2.3 and 4% over the whole concentration range were achieved. The ECA has proved to be more sensitive than the compared tests (ecarin clotting time and a thrombin-based chromogenic assay); a detection limit of 0.011 microg hirudin/ml and a quantitation limit of 0.032 microg hirudin/ml were calculated. The ECA is independent of the variations of the coagulation variables fibrinogen and prothrombin. Neither heparin nor oral anticoagulants interfere with the ECA.
Lange
U
U
HaemoSys GmbH, Medical Faculty, Friedrich Schiller University, Jena, Germany. u.lange@haemosys.de
Nowak
G
G
Bucha
E
E
D001120:Arginine / Q000031:analogs & derivatives; D002863:Chromogenic Compounds; D016903:Drug Monitoring / Q000379:methods; D010450:Endopeptidases; D004792:Enzyme Precursors / Q000378:metabolism; D006629:Hirudins / Q000097:blood; D006801:Humans; D007202:Indicators and Reagents; D008722:Methods; D010875:Pipecolic Acids / Q000097:blood; D012016:Reference Values; D015203:Reproducibility of Results; D015842:Serine Proteinase Inhibitors / Q000032:analysis*; D013449:Sulfonamides; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000378:metabolism
D002863:Chromogenic Compounds; D004792:Enzyme Precursors; D006629:Hirudins; D007202:Indicators and Reagents; D010875:Pipecolic Acids; D015842:Serine Proteinase Inhibitors; D013449:Sulfonamides; D001120:Arginine; D010450:Endopeptidases; D013917:Thrombin; C026812:meizothrombin; C020097:ecarin; C031942:argatroban