Antiplatelet agents inhibit platelet aggregation and red blood cells, reduce their ability to stick together and adhesion (adhesion) to the endothelium of blood vessels. By reducing the surface tension of erythrocyte membranes, they facilitate their deformation when passing through capillaries and improve the fluidity of blood. Antiplatelet agents can not only prevent aggregation, but also cause disaggregation has aggregated platelets.
Apply it to prevent the formation of postoperative thrombi, thrombophlebitis, thrombosis of retinal vessels, cerebrovascular disorders etc., and also to prevent thromboembolic complications of ischemic heart disease and myocardial infarction.
Inhibitory effect on bonding (aggregation) of platelets (and erythrocytes) have to one degree or another medicines of different pharmacological groups (organic nitrates, calcium channel blockers, purine derivatives, antihistamines, etc.). Pronounced antiplatelet effect of NSAIDs, of which a wide application in order to prevent blood clots is aspirin.
Acetylsalicylic acid is currently the main representative of antiplatelet agents. She has an inhibitory effect on spontaneous and induced aggregation and adhesion of platelets, release and activation of platelet factors 3 and 4. It is shown that its anti-aggregating activity is closely connected with the influence on the biosynthesis, liberatiou and metabolism PG. She promotes the release of endothelium of vessels of GHGs, including ПГІ2 (prostacyclin). The latter activates adenylate cyclase, decreases in platelets the content of ionized calcium, which is one of three major mediators of aggregation, and also has disaggregative activity. In addition, acetylsalicylic acid, inhibiting the activity of cyclooxygenase, reduces the formation in platelets of thromboxane A2 — prostaglandin with the opposite type of activity (proaggregatory factor). In high doses, acetylsalicylic acid inhibits the biosynthesis of antithrombotic prostacyclin and other prostaglandins (D2 , E1, etc.). In this regard, as the operation of acetylsalicylic acid administered in relatively small doses (75-325 mg per day).