Phosphate Binders Derived from Natural Ores Contain Many Kinds of Metallic Elements Besides Their Active Ingredient Metals

Most patients undergoing dialysis are required to take many phosphate binder pills to control hyperphosphatemia. Phosphate binders prescribed in Japan are classified into two types: metal-based binders (Ca carbonate, lanthanum carbonate, ferric citrate hydrate, and sucroferric oxyhydroxide) and chemically synthesized polymers (sevelamer hydrochloride and bixalomer). The raw materials of metal-based phosphate binders are natural ores; thus, such binders may contain several other metallic elements. We measured the elemental contents in six metal-based phosphate binders using an inductively coupled plasma mass - spectrometry (ICP-MS) method. As a result, despite being in small amounts, ore-derived phosphate binders contained various elements besides their active ingredient metals: Na, Mg, P, Mn, Fe, Sr, Y, Ba, La, Nd, and Pb in three Ca-based products; Mg, P, Se, Ce, and Gd in one La-based product; and Na, Mg, Al, P, Ca, Ti, Cr, Mn, Co, Ni, Ge, Ba, and La in two Fe-based products. These elements are considered to have originated from pharmaceutical bulk and from pharmaceutical additives. It is unlikely these elements are immediately harmful to patients. However, it should be emphasized that patients undergoing dialysis do not have a urinary excretion route and are administered many phosphate binder pills every day over a long period of time. In the future, pharmaceutical companies may have to disclose standard amounts and/or analytical values regarding the type and quantity of metallic elements in the final formulation or pharmaceutical bulk derived from natural ores.