33484-47-8 4H-Pyrido(1,2-a)pyrimidinium, 6,7,8,9-tetrahydro-3-carboxy-1,6-dimethyl-4-oxo-, methyl sulfate 6,7,8,9-Tetrahydro-3-carboxy-1,6-dimethyl-4-oxo-4H-pyrido(1,2-a)pyrimidinium methyl sulfate MZ-211 Probon acid