COX-2 selective NSAIDs (non-aspirin nonsteroidal anti-inflammatory drugs) were developed to maintain analgesia efficacy while minimizing the side effects associated with COX-1 inhibition. The cyclooxygenase enzyme is shown anchored to the endoplasmic reticulum membrane. Above it, released prostaglandin hormones soar into the cell. Inside it, arachidonic acid is converted into prostaglandins by cyclooxygenase by adding two oxygen molecules. Celecoxib (Celebrex®) COX-2 selective NSAID is blocked from the channel of access for COX-1, but gains entry at COX-2 site, and thereby inhibits the active site for pain prostaglandin creation.