Non-steroidal anti-inflammatory drug

Non-steroidal anti-inflammatory drugs, usually abbreviated to NSAIDs, are drugs with analgesic, antipyretic and antiinflammatory effects: they reduce pain, fever and inflammation. They act by inhibiting cyclooxygenase enzymes, which form prostaglandins from arachidonic acid. Paracetamol (acetaminophen) however does not have any significant anti-inflammatory properties and so is not an NSAID.

Well-known NSAIDs that act as inhibitors of cyclooxygenase-1 (COX-1) are salicylates, (aspirin), diclofenac, indomethacin, ibuprofen, naproxen and piroxicam. COX-1 is also found in the stomach lining. But the prostaglandins here serve a protective role, preventing the stomach mucosa from being eroded by its own acid. When COX-1 inhibitors lower stomach prostaglandin levels, their protective effects are lost, and stomach ulcers and internal bleeding can result.

Newer NSAIDs, such as celecoxib and rofecoxib, are more selective inhibitors of cyclooxygenase-2 (COX-2). This spares some of the harmful effects of older NSAIDs on the stomach lining.