Cyclooxygenase 1 (COX-1); Cyclooxygenase 2 (COX-2) (COX-1; COX-2)

Cyclooxygenase 1 (COX-1) and Cyclooxygenase 2 (COX-2) are isoenzymes that catalyze the first step in prostaglandin and thromboxane biosynthesis from arachidonic acid. COX-1 is constitutively expressed and maintains physiological functions such as gastric mucosa protection and platelet aggregation, whereas COX-2 is inducible and associated largely with inflammation, pain, and fever. Both enzymes have highly conserved structural domains but differ in substrate selectivity and inhibitor sensitivity. They are the principal targets of NSAIDs and coxibs, and selective inhibition of these isoforms is a major strategy in pain and inflammation management. COX-2 is frequently upregulated in many cancers. Safety concerns with their inhibition include gastrointestinal, cardiovascular, and renal risks.

Other names

Prostaglandin-endoperoxide synthase 1 (PTGS1)Prostaglandin-endoperoxide synthase 2 (PTGS2)Prostaglandin G/H synthase 1/2Prostaglandin synthaseProstaglandin synthetaseCOX-1COX-2

Inhibition of prostaglandin and thromboxane synthesis by blocking the cyclooxygenase activity Nonselective COX inhibitors block both isoforms, leading to reduced pain/inflammation and increased risk of GI injury and bleeding Selective COX-2 inhibitors preferentially inhibit COX-2, aiming to reduce pain/inflammation with lower GI risk but increased cardiovascular risk