Synonyms
Clopidogrel
Definition
Plavix®(clopidogrel) is used as a drug and belongs to the group of antiplatelet aggregation inhibitors. It thus prevents blood from clotting and thus prevents the formation of thrombi (blood clots), which potentially lead to embolism (complete dislocation of blood vessels), which can result in a pulmonary embolism or stroke, for example, and is therefore life-threatening if left untreated.
Mechanism of action of Plavix
Blood coagulation is roughly divided into two phases. Primary hemostasis (from Greek hema = blood and stasis = stopping) with the blood platelets (thrombocytes) as the main players, and secondary hemostasis, in which 13 clotting factors play the main role. Both run side by side and never in isolation.
Plavix®(clopidogrel) intervenes inhibiting the primary hemostasis. The platelets are present in an inactive form in the uninterrupted flowing blood (i.e. when no injury has occurred in the surrounding tissue and no drugs are acting). In order to change into the active form, they require various activating substances.
These include thromboxane and ADP (adenosine diphosphate). Only when such a substance has bound to the thrombocyte does it change its shape from relatively round and uniform to spiky with many runners, thus taking the first step towards blood clotting. Only in this prickly form are the thrombocytes able to cross-link with each other and – together with other substances such as fibrinogen – form an insoluble aggregate, which is immensely important for sealing wounds after tissue injuries.
However, such platelet aggregation can also occur undesirably or too violently, thus posing the risk of blood clots forming. Plavix® (clopidogrel) prevents ADP from binding to the platelet by blocking the ADP receptor (P2Y12 receptor). As a result, the blocked platelets cannot be activated and the clotting process does not begin.
Plavix® irreversibly blocks the receptor so that the platelets cannot be activated “for their entire life”. Since platelets have a lifespan of about 10 days, clotting cannot take place completely again until the blocked platelets have been sorted out and new ones have formed. ASS (acetylsalicylic acid), which is usually better known, also has the same principle of action, but via a different inhibition pathway.
All articles in this series:
