Effects of three of the four NSAIDs on PGE2 production in OA cartilage. Percentage changes in PGE2 levels in culture supernatants of osteoarthritic cartilage treated with different NSAIDs are shown. Mean values (n = 5 ± standard error) are presented for indomethacin (open bar), naproxen (light grey bar) and celecoxib (black bar). Effects of aceclofenac were not measured. Statistical differences of the effects of the different NSAIDs compared with untreated controls were calculated using nonparametric paired analysis (*P < 0.05). NSAID, nonsteroidal anti-inflammatory drug; OA, osteoarthritis; PG, prostaglandin.