Pyrimidone derivatives of formula (I) wherein: R1 represents a 4-pyridine ring； R2 represents a hydrogen atom； R3 represents a hydrogen atom； R4 represents : a hydrogen atom； a phenyl ring, this ring being optionally substituted by 1 to 4 substituents selected from a C 1-6 alkyl group, a halogen atom, a C 1-2 halogenated alkyl group, a hydroxyl group, a C 1-6 alkoxy group, a C 1-2 halogenated alkoxy group, R5 represents a hydrogen atom, a C 1-6 alkyl group, a 4-pyridine group, a phenyl group, these groups being optionally substituted, R6 represents a hydrogen atom, a C 1-6 alkyl group, a benzyloxy group, a phenyl C 1-6 alkyl group, these groups being optionally substituted, in form of a free base or of an addition salt with an acid. Use in therapeutic.
