Cyclooxygenase, COX

Cyclooxygenase (COX), also called prostaglandin synthetase, is an enzyme important in the synthesis of prostaglandins and thromboxane from arachidonic acid.

There are two types of cyclooxygenase: COX-1 catalyzes the production of prostaglandins which serve so-called "house-keeping" functions. COX-2 is associated with production of inflammatory prostaglandins and is associated with pathological processes. ^2,3 These two distinct enzymes are encoded by two distinct genes.

Prostaglandins and thromboxane are involved in many pathologic physiological processes ranging from vascular inflammatory response to tissue damage or infection, fever, pain perception, blood clot formation (hemostasis), protection of gastrointestinal tract from the erosive effects of gastric acid, the induction of labor, and the regulation of kidney function. Thus, the inhibition of COX can result in alleviation of symptoms of many diseases, particularly inflammatory joint disease. However, this often occurs with the generation of severe side effects due to the inhibition of physiological functions such as perforations, ulcers, or bleeding from the stomach. ³

Drugs

aspirin has been remarkably successful in the treatment of the pain and swelling of inflammatory disease. This success has resulted in the synthesis of many other "aspirin-like drugs", now referred to as NSAIDs. Aspirin, however, continues to have a unique use in the prevention of thrombosis (formation of clots). Since it produces irreversible inhibition of COX-1, a daily low dose of aspirin will cause a cumulative inhibition of COX-1 in platelets, in the portal circulation. A gradual inhibition of platelets occurs, reducing the possibility of blocking of heart and brain vessels by platelet thrombi. ³

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REF FILE 324-DAC