CP-66,248, a new anti-inflammatory agent, is a potent inhibitor of leukotriene B4 and prostanoid synthesis in human polymorphonuclear leucocytes in vitro.

The effects of (Z)-5-chloro-2,3-dihydro-3-(hydroxy-2-thienylmethylene)-2-oxo-1H- indole-1-carboxamide (CP-66,248), a new anti-inflammatory agent, were tested on the synthesis of the pro-inflammatory arachidonic acid metabolites, LTB4 and PGE2, in isolated human peripheral polymorphonuclear leucocytes. At clinically achievable (i.e. plasma) drug concentration, CP-66,248 reduced A 23187-stimulated LTB4 (IC50 18 +/- 1 microM) and PGE2 (IC50 32 +/- 8 nM) synthesis. The corresponding IC50 values for arachidonic acid-induced LTB4 and PGE2 production were 13 +/- 4 microM and 65 +/- 15 nM, respectively. The inhibitory action of CP-66,248 towards 5-lipoxygenase was comparable with that of timegadine and exceeded that of caffeic acid, and its action against the cyclo-oxygenase pathway was similar to that of other NSAIDs tested. The dual inhibition of cyclo-oxygenase and lipoxygenase pathways of arachidonic acid metabolism is likely to be involved in the anti-inflammatory, antipyretic and analgetic action of CP-66,248 detected in a variety of experimental models.