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Cyclooxygenase-2 (COX-2), also known as prostaglandin-endoperoxide synthase 2 (HUGO PTGS2), is an enzyme that in humans is encoded by the PTGS2 gene. [5] In humans it is one of three cyclooxygenases. It is involved in the conversion of arachidonic acid to prostaglandin H 2, an important precursor of prostacyclin, which is expressed in inflammation.
The inhibition of COX-2 is paramount for the anti-inflammatory and analgesic function of the selective COX-2 inhibitor celecoxib. However, with regard to this drug's promise for the therapy of advanced cancers, it is unclear whether the inhibition of COX-2 plays a dominant role, and this has become a controversial and intensely researched issue.
COX is a common target for anti-inflammatory drugs. The most significant difference between the isoenzymes, which allows for selective inhibition, is the substitution of isoleucine at position 523 in COX-1 with valine in COX-2. The smaller Val 523 residue in COX-2 allows access to a hydrophobic side-pocket in the enzyme (which Ile 523 ...
In 1991 the existence of the COX-2 enzyme was confirmed by being cloned by Dr. Dan Simmons at Brigham Young University. Before the confirmation of COX-2 existence, the Dupont company had developed a compound, DuP-697, that was potent in many anti-inflammatory assays but did not have the ulcerogenic effects of NSAIDs. Once the COX-2 enzyme was ...
COX-2 is an enzyme facultatively expressed in inflammation, and it is inhibition of COX-2 that produces the desirable effects of NSAIDs. [125] When nonselective COX-1/COX-2 inhibitors (such as aspirin, ibuprofen, and naproxen) lower stomach prostaglandin levels, ulcers of the stomach or duodenum and internal bleeding can result. [126]
Newer NSAID drugs called COX-2 selective inhibitors have been developed that inhibit only COX-2, with the hope for reduction of gastrointestinal side-effects. [8] However, several COX-2 selective inhibitors have subsequently been withdrawn after evidence emerged that COX-2 inhibitors increase the risk of heart attack. [9]
Etoricoxib, sold under the brand name Arcoxia, is a selective COX-2 inhibitor developed and commercialized by Merck.It is approved in 63 countries worldwide as of 2007, except the United States where the Food and Drug Administration sent a Non Approvable Letter to Merck and required them to provide additional data.
Rofecoxib is a selective COX-2 inhibitor, or "coxib". Though the class of coxibs includes several agents, degrees of COX-2 selectivity vary among them, with celecoxib (Celebrex) being the least COX-2 selective, and rofecoxib (Vioxx), valdecoxib (Bextra), and etoricoxib (Arcoxia), being highly COX-2 selective. [10]