Patent ID: 7670676

Claim:
A pharmaceutical raw material consisting of: magnetic iron oxide fine particles having an average particle diameter of 5 to 30 nm, a saturation magnetization of 50 to 90 Am 2 /kg, a coercive force of 0 to 1.6 kA/m, a variation coefficient of particle size distribution of not more than 10% and composed of a composition with a spinet structure which is represented by the formula: MOFe 2 O 3 wherein M is a divalent metal represented by the formula: MOFe 2 O 3 , is Fe, Mg, or Fe and Mg with the proviso that a total amount of Fe and Mg is not more than 1 mol based on 1 mol of Fe 2 O 3 , and ultrapure water, said material having a pH of not less than 9.0 and being in the form of a monodisperse colloid sterile aqueous solution containing 5 to 50 mg/mL of the magnetic iron oxide fine particles.