Dilute Russell's Viper Venom Clotting Time (DRVVT) is Useful for the Routine Monitoring of Newer Non‐Vitamin K Anticoagulants

Abstract

The newer non‐vitamin K anticoagulants such as rivaroxaban (Bayer Healthcare) (R), apixaban (BMS/Pfizer) (A) and dabigatran (Boehringer Ingleheim) (D) have been approved to manage thrombotic and cardiovascular disorders. This study was designed to determine which of the available clotting assays could be used to monitor these new oral anticoagulants in plasma.MaterialsCitrated blood was drawn from ten donors and platelet poor plasma (PPP) was obtained. The PPP was supplemented with A, R and D in a concentration range of 0‐1.0 ug/ml. In addition, plasma samples, containing varying concentrations of either A, R or D were also blindly analyzed. The plasma samples were analyzed using PT/INR (Innovin, Seimens, Deerfield,IL), APTT reagent (Platelin, TCoag, Ireland) dilute Russell's viper venom time (DRVVT) and DRVVT confirm (HemosIL, Instrumentation Laboratories (Bedford, MA).ResultsIn the PT and APTT assays a concentration dependent modest increase in clotting time was observed. In contrast, both the DRVVT and DRVVT confirm assays the concentration‐response curves were straight lines with a steep slope. Therefore, it was possible to extrapolate the concentrations of the unknown samples using both of these assays. In addition , there was a good correlation between the calculated concentration and the actual concentration in the range of 50 to 1000 ng/ml (r2=0.82) with both assays.ConclusionsThese results suggest the dRVVT and DRVVT confirm assays are sensitive to A, D and R at concentrations > 50 ng/ml. Therefore, A,D and R can be monitored by these assays. Both of these assays are commercially available and can be readily adapted to any automated instrument.