Effect of low molecular weight heparin on clot rate in vitro

Abstract

Objective To study the in vitro effects of different doses and different kinds of LMWH on CR, and to determine whether the CR test could be used to monitor LMWH. Methods The CR value was measured with different reagents ( glass beads, celite and kaolin ) in blood samples from twenty volunteer donors, which were spiked with increasing concentration of LMWH ( dalteparin, 0-1.8 IU/ml ). Then the CR test was performed again on the same blood samples spiked with the same concentration ( 0. 8 IU/ml ) but different LMWH ( dalteparin, enoxaparin and nadroparin ). Regression analysis was performed to establish a regression equation from corresponding LMWH levels. Results With the increasing of dalteparin dose, CR values were reduced gradually for all three reagents. When the concentration of dalteparin was 0-1.8 IU/ml,the value of CR was 20. 0-4. 5 IU/min for glass beads, 26. 1-6.6 IU/min for celite and 27. 2-7. 5 IU/min for kaolin. An exponential relationship was observed between the CR value and dalteparin concentration for three reagents( R2 = -0.796, -0.884, -0.921 ,P ＜0.01 ). All three kinds of LMWH with the same concentration (0.8 IU/ml ) induced a different change in CR. The value of CR was 7.4 IU/min with dalteparin,8. 5 IU/min with enoxaparin and 8.5 IU/min with nadroparin. Compared with the control group ( CR was 17.6 IU/min ), three kinds of LMWH had statistical significance ( t = 18.45, 12. 33, 14. 93, P ＜ 0.01 ).Compared with the enoxaparin and nadroparin, dalteparin induced a higher CR value ( t = 2. 552,2. 924,P＜0. 05 ). Conclusions There is an exponential relationship between CR value and dalteparin concentration for three reagents. Three kinds of LMWH can significantly reduce the value of CR. CR test can be used to monitor the anticoagulant effect of LMWH. Key words: Heparin,low-molecular-weight; Fibrin; Indicators and reagents; In vitro