Abstract: Compounds of formula I wherein: one of X or Y represents N and the other represents C; R1 represents hydrogen, methyl, halogen, cyano, nitro, —CHO, —COCH3 or —COOR4; PR2 represents optionally-substituted aryl or heteroaryl; R3 represents C1-8 alkyl, C1-8 haloalkyl or —NR4R6; R4 represents hydrogen, C1-8 alkyl or arylC0-8 alkyl; R6 represents hydrogen, C1-8 alkyl, arylC1-8 alkyl, —COR8 or —COOR8; R8 represents C1-8 alkyl or C1-8 haloalkyl; aryl in the above definitions represents phenyl or naphthyl; and heteroaryl in the above definitions represents pyridine, pyrazine, pyrimidine or pyridazine, which can be optionally fused to a benzene ring. These compounds are useful as cyclooxygenase-2 inhibitors.