Trends in the development of antithrombotic agents

In venous thrombosis and pulmonary embolism, blood solidifies to form a clot, which is a homogenous structure containing fibrin, red cells, white cells and platelets. Heparin and oral anticoagulant agents are effective in prophylaxis and treatment. In the future, fibrinolytic therapy (urokinase) and Arvin may prove more useful.

An arterial thrombus consists of platelet masses separated by fibrin strands; any agent that either prevents platelets from sticking to each other or prevents the formation of fibrin might theoretically be effective in preventing thrombosis. However, anticoagulant drugs are at best only marginally useful; although there are other ways of preventing fibrin formation, it now seems reasonable to investigate clinically agents that affect platelet behavior. Some of the methods of studying platelet behavior are described and their limitations are emphasized. Some of the many compounds known to influence platelets are discussed, and those which seem most worthy of clinical trials are indicated.