LE PHENOMENE INFLAMMATOIRE

COX1 et COX2
Il existe deux formes (stéréo-isomères??) de la PGH-synthétase :
---- L'isoforme 1 ou COX1 responsable des effets toxiques sur le rein et l'estomac.
---- L'isoforme 2 ou COX2 responsable des effets anti-inflammatoires et antalgiques.
Les AINS sont en majorité non sélectifs.
Le diclofénac (VOLTARENE ®, XENID ®D) et de nouvelles molécules comme le méloxiam (MOBIC ®) inhibent plus sélectivement la COX2. Son intérêt est en cours d'évaluation (étude Melissa et Select)

Des produits hautement délectif sont en étude et seront une importante avancée thérapeutique en rhumatologie.
Voir Celebrex ®
Voir Vioxx ® rofecoxib

MISE A JOUR Juin 1999

Aspirin and other traditional nonsteroidal antiinflammatory drugs (NSAIDs) inhibit the enzyme cyclooxygenase (COX), which is involved in the production of prostaglandins. Prostaglandins are intercellular messengers that are found in high concentrations at sites of chronic inflammation. They are capable of causing vasodilatation, increasing vascular permeability and sensitizing pain receptors.
Although many NSAIDs were developed that block the action of COX, all produced gastritis in many patients -- especially the elderly, those patients with a prior history of peptic ulcer disease and patients on corticosteroids.

It is now known that there are two COX enzymes -- cyclooxygenase 1 (COX-1) and cyclooxygenase 2 (COX-2). The traditional NSAIDs bind to the active sites of both COX-1 and COX-2. Gastritis is caused by the inhibition of COX-1, which is a gastric COX that regulates mucosal cell production of mucous. (The mucous acts as a barrier to the acid and pepsin present in gastric secretions.)