The invention provides novel substituted phenylamino isonicotinamide compounds (I), pharmaceutically acceptable salts, solvates or prodrugs thereof, wherein X, R1, R2, R3, R4, R5 and R6 are as defined in the specification. Said compounds are MEK inhibitors useful in the treatment of hyperproliferative diseases related to the hyperactivity of MEK, such as restenosis, as well as diseases modulated by the MEK cascade, such as cancer and inflammation. Also disclosed is the use of such compounds in the treatment of hyperproliferative diseases in mammals, especially humans, and pharmaceutical compositions containing such compounds.