The recharacterization of a polysaccharide iron complex (Niferex)

An oral hematinic marketed as "Niferex," the active component of which is a polysaccharide-iron complex (PIC), has recently been recharacterized. PIC is synthesized by the neutralization of an FeCl3 carbohydrate solution. Original characterization of this complex by Mössbauer spectroscopy and X-ray powder diffraction suggested that the iron-rich core was similar in structure to the mineral ferrihydrite. Higher precision X-ray powder diffraction now indicates that the core has a long-range order more similar to the mineral akaganéite, beta-FeOOH, than to ferrihydrite. This structure has been found for other similar ferric iron-carbohydrate polymers, especially those synthesized by the hydrolysis of FeCl3. Also discussed are the variable temperature (24-295 K) Mössbauer spectroscopic data for PIC. The first example of EXAFS data for polysaccharide iron complexes confirms that the iron is in an octahedral environment, coordinated to oxygen, with a short-range order similar to that for ferritin. The second iron shells in the PIC samples are less ordered than the second shell in ferritin. The size of the PIC core was found to be approximately 5 nm by X-ray powder diffraction, and is of the same order of magnitude as the ferritin core.