alt of thebenzylsuccinic acid derivative represented by the above formula (I) or its hydrate.Diluents can include, for example, cellulose or cellulose derivatives such as microcrystalline cellulose and the like; starch or starch derivatives such as corn starch, wheat starch, cyclodextrin and the like; sugar or sugar alcohol such aslactose, D-mannitol and the like; and inorganic diluents such as dr