» Ferumoxsil Oral Suspension is an aqueous suspension of silicone-coated superparamagnetic iron oxide. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of iron (Fe). It contains a preservative and a thickening agent. It may contain suitable colors, flavors, and sweetening agents. Ferumoxsil is poly[N-(2-aminoethyl)-3-aminopropyl]siloxane-coated nonstoichiometric magnetite [FeO_X(C₅H₁₃N₂SiO₂)_Y].