A series of six pyrazoline ring derivatives as a pharmacophore were incorporated to the naproxen; to increase its size were synthesized and preliminarly evaluated as antiinflammatory agents with expected selectivity toward COX-2 enzyme. In vivo acute antiinflammatory effects of the final compounds (5a-f) were evaluated in rats using egg-white induced edema model of inflammation. The tested compounds and the reference drug (naproxen) produced significant reduction of paw edema with respect to the effect of …