Determination of antithrombin-dependent factor Xa inhibitors by prothrombin-induced clotting time.

Prothrombinase-induced clotting time (PiCT) determines the anticoagulant effects of heparins, low molecular weight heparins (LMWHs), and direct thrombin inhibitors. At present, this is the only method that measures the effects of all of these inhibitors, in contrast to the prothrombin time, activated partial thromboplastin time (aPTT), Heptest, ecarin clotting time, and the chromogenic assays. The antithrombin-dependent direct factor (F) Xa inhibitors fondaparinux and idraparinux were compared with the LMWH dalteparin on PiCT, aPTT, Heptest, and chromogenic anti-FXa assays in pooled human normal plasma samples.