The pharmaceutical formulations according to the present invention include an alkyl sulfate salt and a compound represented by general formula below (where R 1 to R 4 are as defined in the specification) or tautomers thereof, or pharmaceutically acceptable salts thereof本發明之醫藥製劑,包含烷基硫酸酯鹽及下述通式(I)所示之化合物或其互變異構物、或者其藥學上容許之鹽(式中,R1~R4之定義,如說明書中所載)。