Experimental prevention of venous thrombosis.

Modern antithrombotics are no more represented merely by anticoagulants. The experiments with a series of thrombosis models enabled us to redefine several new groups appearing as yet under the name "antiplatelet agents" or "antiaggregants". The group comprises particularly acetylsalicylic acid, dipyridamole, hydroxychloroquine, sulfinpyrazone, clofibrate and suloctidyl. It was demonstrated experimentally that these drugs act predominantly by increasing endothelial stability against various noxious agents. This stabilizing effect, independent on the anticoagulant activity, is present also after the administration of oral anticoagulants in doses by one order lower in comparison with the anticoagulant dosage. In fact, the latter dosage has an opposite effect on endothelium and increases the number of circulating endothelial cells. Nevertheless, this unfavourable effect may be inhibited by suitable endotheloprotective drugs (e. g. prenylamine) and in this way an important portion of bleeding complications after oral anticoagulants may be abolished.