Piroxicam, a potent inhibitor of prostaglandin production in cell culture. Structure-activity study.

The new non-steroidal antiinflammatory (NSAI)2 agent, piroxicam [4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide], is a highly active inhibitor of prostaglandin (PG) synthesis by methylcholanthrene transformed mouse fibroblasts (MC5-5) and rabbit synovial cells in culture. Comparison of the PG biosynthesis inhibitory activity of piroxicam with other NSAI drugs in these experiments ranks piroxicam as among the most potent agents of this type now known. Some specific modifications of piroxicam's structure result in significant loss in PG synthesis blocking activity.