On the mechanism of the anti-inflammatory action of the newly-synthesized benzoylpyrazolone derivatives.

One of the basic mechanisms of action of the nonsteroid anti-inflammatory agents is associated with prostaglandin synthesis. The effects of 1-phenyl-3-methyl-4 (4)-chlorbenzoylpyrazolone-5 (No. 151) and 1-phenyl-2-benzoyl-3-methylpyrazolone-5 (No. 76) on the quantity of prostaglandins and on the invasion of polymorphonuclear leucocytes in inflammatory exudate have been studied. Experimental inflammation is induced after Higgs et al. (1976). The level of prostaglandins in the exudate is determined through cascade superfusion of isolated smooth-muscle organs. The level of prostaglandins is found to decrease in animals treated with No. 151 and indomethacine, and to increase under the effect of No. 76. The invasion of the focus with polymorphonuclear leucocytes is inhibited by No. 151 and indomethacine. On the basis of the results obtained, No. 151 is assumed to belong to the group of prostaglandin-synthetase inhibitors, according to its mechanism of action.