[Haemostaseology].

The design and development of new antithrombotics, i.e. anticoagulants and antiplatelet drugs, is a rapidly expanding area of pharmacological research. New anticoagulants, i.e. inhibitors of thrombin formation and action have been developed and some of them are already in clinical use. This includes hirudin and its analogs, such as bivalirudin. In contrast to heparins, these compounds as well as low-molecular weight inhibitors of thrombin and factor Xa directly inhibit thrombus-associated generation and action of thrombin, eventually associated with a reduced bleeding tendency. Orally active compounds are available and currently subject of clinical trials. It appears possible that these new agents may replace cumarins as oral anticoagulants, specifically in long-term use, in the near future. The introduction of clopidogrel marks another important development in the field of antiplatelet drugs. Synergistic actions of this compound with acetylsalicylic acid and GP-IIb/IIIa-antagonists because of their different mode of action enhance the antithrombotic potential considerably and have been clinically confirmed. Despite of this optimistic outlook, the individual risk/benefit ratio of these new drugs, in particular in the area of anticoagulants, still needs to be defined.