The present invention is related to a method for phosphate-binding by using an enteric coated pharmaceutical composition comprising chitosan citrate. The chitosan citrate used in said pharmaceutical composition is of 50 to 75% deacetylation, which exhibits excellent phosphate-binding ability in alkaline environment.本發明關於一種磷結合方法,其使用一腸溶型醫藥組合物。該腸溶型醫藥組合物包含甲殼素檸檬酸鹽。使用於該腸溶型醫藥組合物中的甲殼素檸檬酸鹽具有50至75%的去乙醯化,並且在鹼性環境下展性優異的磷結合能力。