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.

Comparison of two different ecarin clotting time methods.

Background: Ecarin Clotting Time (ECT) assay specifically determines the inhibition of meizothrombin by direct thrombin inhibitors (DTI). Blood coagulation factor levels lowered by vitamin K antagonists (VKA) may prolong ECT. Concomitant treatment of VKA with DTI may influence differently the two published ECT methods.

Treatment of patients with a history of heparin-induced thrombocytopenia and anti-lepirudin antibodies with argatroban.

Patients with heparin-induced thrombocytopenia (HIT) type II require anticoagulation with non-heparin immediate acting anticoagulants. Danaparoid may cross react with HIT-antibodies and lepirudin may generate anti-lepirudin antibodies influencing anticoagulation. We hypothesised, that the synthetic small molecular thrombin inhibitor argatroban does not induce immunoglobulins reacting towards lepirudin in patients with anti-lepirudin antibodies in the history and that titration of the anticoagulation may be easier with argatroban.

Effects of vitamin K antagonist phenprocoumon on activated partial thromboplastin time measurement of direct thrombin inhibitors.

The activated partial thromboplastin time (aPTT) is currently the most common test used to measure the anticoagulation intensity of heparins and direct thrombin inhibitors (DTIs). Vitamin K antagonists variably affect aPTT reagents. Interactions between heparin and DTIs occur during concurrent therapy.

Treatment of heparin-induced thrombocytopenia with fondaparinux.

Anticoagulation of patients with heparin-induced thrombocytopenia (HIT) may be limited by cross-reaction of HIT antibodies with danaparoid and generation of antibodies during therapy with lepirudin. We used fondaparinux to treat 6 patients with a history of HIT with thromboembolism and 2 patients with thrombocytopenia during low-molecular-weight heparin administration.

Effects of lepirudin, argatroban and melagatran and additional influence of phenprocoumon on ecarin clotting time.

Introduction: Direct thrombin inhibitors (DTI) prolong the ecarin clotting time (ECT). Oral anticoagulants (OA) decrease prothrombin levels and thus interact with actions of DTIs on the ECT method during concomitant therapy.

Materials And Methods: Actions of lepirudin, argatroban and melagatran on ECT were investigated in normal plasma (NP) and in plasma of patients (n=23 each) on stable therapy with phenprocoumon (OACP).

Treatment of venous thromboembolism with the oral thrombin inhibitor, ximelagatran.

Background: Venous thromboembolic diseases are treated initially with low molecular weight heparin followed by oral coumarins.

Objectives: To investigate an orally available direct thrombin inhibitor for the acute treatment of venous thromboembolism as well as for prophylaxis of recurrent events.

Methods: The direct thrombin inhibitor ximelagatran was compared with subcutaneous LMW heparins followed by oral warfarin in a double-blind randomized prospective multicenter trial in patients with acute VTE.

Monitoring of anticoagulant effects of direct thrombin inhibitors.

Monitoring of direct thrombin inhibitors with the activated partial thromboplastin time (aPTT) is limited by poor linearity and reproducibility. Recently, direct prothrombin activation methods have been developed for coagulation analysis: ecarin clotting time (ECT) and prothrombinase-induced clotting time (PiCT). Laboratory monitoring of the direct thrombin inhibitors lepirudin, argatroban, and melagatran was analyzed and compared with monitoring unfractionated heparin (UFH).