Synonyms: Pyrimido[5,4-d]pyrimidine-2,4,6,8(3H,7H)-tetrone,1,5-dihydro-, disodium salt (9CI); Pyrimido[5,4-d]pyrimidine-2,4,6,8-tetrol,disodium salt (8CI); Sodium,[(4,8-dihydroxypyrimido[5,4-d]pyrimidine-2,6-diyl)dioxy]di- (7CI); Homouricacid, disodium salt