Pharmacologically active phenylalkanoyl substituted imidazo (4,5-C) pyridines

This invention relates to substituted imidazopyridine dervatives having the following formula and isomers thereof; or a pharmaceutically acceptable acid addition salt thereof: wherein R1 and R2 are each independently selected from hydrogen; straight or branched chain alkyl of 1 to 15 carbon atoms; cycloalkyl of 3 to 8 carbon atoms; substituted cycloalkyl which can be substituted one or more by alkyl of 1 to 6 carbon atoms; phenyl; substituted phenyl which can be substituted one or more by alkyl of 1 to 6 carbon atoms or halogen; straight or branched alkenyl having 3 to 15 carbon atoms. y is phenyl or phenyl substituted once or more than by alkyl of 1 to 6 carbon atoms; alkoxy wherein the alkyl is 1 to 6 carbon atoms; and halogen selected from the group consisting of bromo, fiuoro or chloro. m is an integer from 0 to 5. n is an integer from 1 to 5. R3 is a group substituted at one or more of the 4, 6 or 7 positions of the pyridine ring said groups being independently selected from hydrogen, alkyl of 1 to 6 carbon atoms; halogen wherein the halogen is selected from bromo, fluoro, or chloro; or alkoxy wherein the alkyl is 1 to 6 carbon atoms; R4 is hydrogen or alkyl of 1 to 4 carbon atoms. useful in the treatment of diseases or disorders mediated by platelet-activating factor. This invention also relates to pharmaceutical compositions of such substituted imidazopyridines.