A novel recombinant tissue factor assay for measuring the anti-Xa effect of Low-Molecular-Weight Heparin (LMWH): implications for interventional coronary procedures
Abstract number: P1895
Laduca* F., Lee T., El Rouby S., Zucker M., Cohen M.
*International Technidyne Corporation, USA; ITC, USA; Newark-Beth Israel, USA
Intensive LMWH therapy for unstable angina, which may lead to interventional coronary procedures, creates anti-coagulation management problems, particularly in patients with renal compensation. Consequently, an increasing need for monitoring of LMWH has been cited in the literature to optimize therapy. We have developed a fast, convenient, economical, point of care (POC) assay for measuring the anti-Xa effect of LMWH, using a proprietary mixture of recombinant rabbit brain tissue factor (RBTF, Pel-Freez Corp.), synthetic phospholipids to lipidate the RBTF and a formulation buffer. This whole blood, single-step assay performed using the Hemochron Jr. Signature+ system (International Technidyne Corp) provides appropriate sensitivity within the therapeutic LMWH concentration range of 0.61.0 anti-Xa U mL-1. Using fresh blood samples from normal donors (n = 10) known amounts of enoxaparin (Lovenox, Aventis Corp.) were added and the clotting times shown in the table were determined.
A significant variation was observed amongst the donors indicating that such a monitoring assay would be useful to establish safe anti-coagulation during coronary interventions. Preliminary clinical feasibility demonstrated a proportional increase of the LMWH assay clotting time to the anti-Xa level, suggesting that appropriate safe target times could be identified. Studies of other LMWH preparations (dalteparin, Fragmin, Pharmacia Upjohn Corp. and tinzaparin, Innohep Bristol Meyers Squibb DuPont Corp.) demonstrated that the LMWH doseresponse clotting time was specific for each agent and reflective of the anti-coagulant effect of each agent.
A novel precise and sensitive POC assay which measures the anti-Xa effect of LMWH has been developed which provides the opportunity to deliver individualized patient LMWH therapy during interventional coronary procedures, such that the risks associated with ineffective anti-thrombotic prophylaxis, particularly undesirable clotting and bleeding, are avoided.
To cite this abstract use the following format:
Journal of Thrombosis and Haemostasis 2003; 1 Supplement 1 July: abstract number
|Subject:||Clinical trials: heparins/LMWH|
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