Cyclooxygenase (COX) is a tissue enzyme that is responsible for tissue formation of important biological mediators called prostaglandins. Prostaglandins are involved in pain, inflammation and fever as well as cytoprotection in the stomach, hemostasis and blood flow in the kidneys. NSAIDS (non steroidal anti-inflammatory drugs) are used medicinally to block the cyclooxygenase and thus they act as pain killers, antipyretic drugs and for fighting some aspects of inflammatory reaction.

There are two isoenzymes, cyclooxygenase-1 and cyclooxygenase-2. Novel group of NSAIDs targets specifically cyclooxygenase-2 in this way avoiding a lot of side-effects that non-specific NSAIDS typically have.