Patent ID: 7220553

Claim:
A method of monitoring the effect of Factor Xa (FXa) inhibitors treatment comprising the steps of: a) collecting a plasma sample from a mammal that has received an FXa inhibitor; b) dividing said plasma sample into portions, saving one portion as the control plasma and adding serial dilutions of FXa inhibitor to other portions; c) adding a solution of Russell's viper venom (RVV-X) to plasma samples defined in b); d) comparing FXa activity measured for the control plasma with the residual FXa activity measured for the plasma samples with added FXa inhibitor; e) constructing a standard curve of dose-dependent inhibition of RVV-X induced by FXa inhibitor; and f) estimating the concentration of FXa inhibitor at various points in time during the FXa inhibitor treatment by using the standard curve.