Synonyms: 3-[2-[4-(2,4-Difluorobenzoyl)piperidin-1-yl]ethyl]-2-methyl-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidin-4-one,4H-Pyrido[1,2-a]pyrimidin-4-one, 3-[2-[4-(2,4-difluorobenzoyl)-1-piperidinyl]ethyl]-6,7,8,9-tetrahydro-2-methyl-, 3-[2-[4-(2,4-Difluorobenzoyl)-1-piperidinyl]ethyl]-6,7,8,9-tetrahydro-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 3-[2-[4-(2,4-Difluorobenzoyl)piperidino]ethyl]-6,7,8,9-tetrahydro-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, Risperidone Imp. H (EP), Risperidone Difluoroketone