Nonsteroidal anti-inflammatory drugs inhibit the isoenzymes COX-1 and COX-2 of the cyclooxygenase, most of the times with the affinity to one form more pronounced than the other. The inhibition can be permanent or reversible. Alongside thre aree so-called selective COX-2 inhibitors, which specifically inhibit the cyclooxygenase 2 which is upregulated during inflammatory reactions.
The enzyme acts in the synthesis pathway of prostaglandins and thromboxanes; through its inhibition these signal molecules necessary for inflammatory reactions are not synthesized anymore. Therefore, the prostaglandine-mediated pain and inflammatory signs will decrease.