Iron oxide complexes, pharmacological compositions and unit dosage thereof, and methods for their administration, of the type employing an iron oxide complex with a polyol, are disclosed. The pharmacological compositions employ a polysaccharide iron oxide complex, wherein the polysaccharide is a modified polyol such as a carboxyalkylated reduced dextran. The complex is stable to terminal sterilization by autoclaving. The compositions are suitable for parenteral administration to a subject for the treatment of iron deficiencies or as MRI contrast agent. The complex is substantially immunosilent, provide minimal anaphylaxis and undergo minimal dissolution in vivo. The pharmacological compositions of the complex contain minimal free iron which can be quantified by a variety of methods.