2- or 3-cyanoiminoquinoxaline derivatives useful as glutamate receptor antagonists

A cyanoiminoquinoxaline derivative of the formula (II) is disclosed, wherein: X and Y are each independently O or NCN, provided that at least one of X and Y is NCN; R1, R2, R3, and R4 are each independently hydrogen, halogen, nitro, optionally substituted heterocyclic group etc.; R5 is hydrogen hydroxy, optionally substituted lower alkyl; R1 and R2, R2 and R3, R3 and R4, and R4 and R5, each taken together with the adjacent atoms may form a carbocycle which may be substituted or may contain a heteroatom(s). Such compounds are useful as preventive or therapeutic agents for diseases due to hyperexcitation of glutamate receptors, including stroke, cerebral infarction.