MULTICENTRIC EVALUATION OF HEPARINASE ON APTT, THROMBIN CLOTTING TIMEAND A NEW PT REAGENT BASED ON RECOMBINANT HUMAN TISSUE FACTOR

In a multicentric study the influence of heparinase (Hepzyme(TM)) was evaluated on activated partial thromboplastin time, thrombin clotting time and prothrombin time using the recombinant human tissue factor an d synthetic phospholipid (phosphatidylcholine and phosphatidylserine r eagent). Hepzyme itself does not have any influence on normal coagulat ion values of activated partial thromboplastin time (aPTT) and prothro mbin time (PT) assays whereas thrombin clotting time was prolonged by 10% (n=60). In patients treated with unfractionated heparin for recent deep vein thrombosis (n=47), plasma levels of aPTT, PT and thrombin c lotting time (TCT) returned to the normal range in 100%, 97% and 91% a fter treatment with heparinase, respectively. Plasma samples of patien ts on coumarin were spiked with 2IU heparin/ml (n=40) and were treated with heparinase. aPTT returned to baseline levels in 97.5%, PT in 99% and TCT in 69% of the samples. Plasma samples of patients receiving b oth heparin and coumarin were treated with heparinase (n=18).aPTT and TCT values were shortened substantially and displayed the prolongation due to the effect of oral anticoagulants. PT values in these patients were also shortened Freezing of plasma samples after treatment with h eparinase resulted in a prolongation of the coagulation times in 15% o f PT, 7% of aPTT and not of TCT values. The results show that treatmen t of plasma samples with heparinase abolishes the effect of unfraction ated and low molecular weight heparin in vitro and ex vivo in patients during simultaneous treatment with oral anticoagulants. The use of he parinase may be of significance in patients with concomitant treatment of heparin and oral anticoagulants.