Pyridine and pyrimidine derivatives

A compound of formula (I)

• wherein
• X is C—R5;
• R1 and R2 are independently hydrogen or lower alkyl;
• R3 is heterocyclyl;
• heterocyclyl mono-, di-, or tri-substituted, independently, by lower alkyl, lower alkoxy, perfluoro-lower alkyl, amino or halogen;
• aryl;
• or aryl mono-, di-, or tri-substituted, independently, by halogen, lower alkyl, lower alkoxy, amino or perfluoro-lower alkyl;
• R4 is lower alkyl;
• lower alkoxy;
• lower alkylthio;
• heterocyclyl;
• heterocyclyl mono-, di-, or tri-substituted, independently, by lower alkyl, lower alkoxy, perfluoro-lower alkyl, amino or halogen;
• aryl;
• aryl mono-, di-, or tri-substituted, independently, by lower alkyl, lower alkoxy, halogen, amino, or perfluoro-lower alkyl;
• aryloxy lower alkyl or cycloalkyl;
• R5 is hydrogen or lower alkyl;
• or a pharmaceutically acceptable salt thereof.