Ecarin Chromogenic Assay

Zusammenfassung

Der ECA (ecarin chromogenic assay) wurde zur quantitativen Bestimmung von direkten Thrombininhibitoren entwickelt. Er ist eine Weiterentwicklung der ECT (ecarin clotting time) und basiert wie diese auf der Prothrombinaktivierung durch Ecarin, einem Schlangengiftenzym aus Echis carinatus. Durch die entstehenden Aktivierungsprodukte Meizothrombin und Meizothrombin-Des-Fragment 1 wird im ECA ein chromogenes Substrat gespalten, während im Gerinnungsassay ECT plasmatisches Fibrinogen zu Fibrin umgesetzt wird.

Die Aktivität von Meizothrombin und Meizothrombin-Des-Fragment 1 wird konzentrationsabhängig durch direkte Thrombininhibitoren gehemmt. Der ECA kann als ECA-H zur quantitativen Hirudinbestimmung und als ECA-T zur Bestimmung von synthetischen Thrombinhemmstoffen eingesetzt werden. Am Beispiel von Hirudin, Argatroban und Melagatran erwies sich der ECA als äußerst präzise und sensitive Methode, die die Vorteile der ECT mit denen chromogener Tests verbindet. Im Vergleich zu aPTT und ECT weist der ECA sehr geringe interindividuelle Schwankungen auf. Er wird weder von der Prothrombin-noch von der Fibrinogenkonzentration im Plasma beeinflusst.

Summary

The ecarin chromogenic assay (ECA) was developed for quantitative determination of direct thrombin inhibitors. As a further development of the ecarin clotting time (ECT), the ECA is based on the same principle, the activation of prothrombin by ecarin a snake venom from Echis carinatus. In the ECA the prothrombin activation products meizothrombin and meizothrombin-desF1 cleave a chromogenic substrate, whereas in the clotting assay ECT plasma fibrinogen is converted to fibrin.

The activity of meizothrombin/meizothrombin-desF1 is inhibited in a concentration-dependent fashion by direct thrombin inhibitors. The ECA can be used as ECA-H for quantitative determination of hirudin and as ECA-T for determination of synthetic thrombin inhibitors. As shown for hirudin, argatroban and melagatran, the ECA turned out as a very precise and sensitive method, which combines the advantages of ECT with those of chromogenic assays. In ECA very low interindividual variations were found compared to aPTT and even ECT. The ECA is independent of the variations of the coagulation variables prothrombin and fibrinogen.

Schlüsselwörter

Ecarin Chromogenic Assay - direkte Thrombininhibitoren - Hirudin - Argatroban - Melagatran

Keywords

Ecarin chromogenic assay - direct thrombin inhibitors - hirudin - argatroban - melagatran

• Literatur

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