PYRAZINE COMPOUNDS

摘要

A compound of formula (I) wherein R1 is selected from the group consisting of phenyl substituted by one or more halogen atoms, naphthyl and naphthyl substituted by one or more halogen atoms; R2 is selected from the group consisting of -NH2 and -NHC(=O)R a; R3 is selected from the group consisting of -NR b R c, -NHC(=O)R a and hydrogen, R4 is selected from the group consistin g of hydrogen, -C1-4alkyl, -C1-4 alkyl substituted by one or more halogen atoms, - CN, -CH2OH, -CH2OR d and -CH2S(O) x R d; wherein R a represents C1-4 alkyl or C3-7cycloalkyl, and R b and R c, which may be the same or different, are selected from hydrogen and C1-4 alkyl, or together with the nitrogen atom to which th ey are attached, form a 6-membered nitrogen containing heterocycle, which heterocyc le can be further substituted with one or more C1-4 alkyl; R d is selected from C1-4 alkyl or C1-4 alkyl substituted by one or more halogen atoms; x is an interg er zero, one or two; and pharmaceutically acceptable derivatives thereof; with the proviso that R1 does not represent (a); when R2 is -NH2, and both R3 and R4 are hydrogen; the compounds (I) are sodium channel blockers and may be used for treatment of diseases such as epilepsy.