A triazinone derivative represented by formula (I) wherein: wherein: Z represents a bond, a carbonyl group, a methylene group optionally substituted by one or two groups chosen from a C 1-6 alkyl group, a hydroxyl group, a C 1-6 alkoxy group； R1 represents a 4-pyridine ring； R2 represents a hydrogen atom, a C 1-6 alkyl； R3 represents a hydrogen atom, a C 1-6 alkyl group； R2 and R3 may form together a 6 membered cycle with the nitrogens caring R2 and R3 optionally substituted； R4 represents: a phenyl ring, being optionally substituted； n represents 0 to 2； in form of a free base or of an addition salt with an acid. These compounds are useful as GSK3-² inhibitors.
