Relative efficacy of selective COX-2 inhibitors compared with over-the-counter ibuprofen.

Non-steroidal anti-inflammatory drugs (NSAIDs) suppress the activity of both isoforms of cyclo-oxygenase (COX). Inhibition of COX-1, the constitutive isoform, is primarily responsible for the adverse gastrointestinal effects of the NSAIDs whereas inhibition of COX-2, the inducible isoform, accounts for their therapeutic effects. COX-2 inhibitors such as celecoxib and rofecoxib appear to be as effective as non-selective NSAIDs in the treatment of chronic inflammatory disease but their analgesic efficacy and their safety at the higher doses required for analgesia are less certain. There is consistent evidence that COX-1 plays a major role in the early pain response following injury and that analgesia is increased when both COX-1 and COX-2 are inhibited simultaneously. Early postoperative nociception may cause hyperalgesia at a later time by a process of central plasticity. In an experimental model of pain, ibuprofen promptly suppresses prostaglandin E2 concentrations whereas celecoxib has no discernible effect until 90-120 minutes postoperatively, when COX-2 activity is induced. Both drugs significantly reduce pain compared with placebo but celecoxib appears to have a slower onset of action. The analgesic effect of ibuprofen is well characterised for acute pain and short-term treatment is well tolerated.