title: Ferrous iron content of intravenous iron formulations.
abstract: The observed biological differences in safety and efficacy of intravenous (IV) iron formulations are attributable to physicochemical differences. In addition to differences in carbohydrate shell, polarographic signatures due to ferric iron [Fe(III)] and ferrous iron [Fe(II)] differ among IV iron formulations. Intravenous iron contains Fe(II) and releases labile iron in the circulation. Fe(II) generates toxic free radicals and reactive oxygen species and binds to bacterial siderophores and other in vivo sequestering agents. To evaluate whether differences in Fe(II) content may account for some observed biological differences between IV iron formulations, samples from multiple lots of various IV iron formulations were dissolved in 12 M concentrated HCl to dissociate and release all iron and then diluted with water to achieve 0.1 M HCl concentration. Fe(II) was then directly measured using ferrozine reagent and ultraviolet spectroscopy at 562 nm. Total iron content was measured by adding an excess of ascorbic acid to reduce Fe(III) to Fe(II), and Fe(II) was then measured by ferrozine assay. The Fe(II) concentration as a proportion of total iron content [Fe(III) + Fe(II)] in different lots of IV iron formulations was as follows: iron gluconate, 1.4 and 1.8 %; ferumoxytol, 0.26 %; ferric carboxymaltose, 1.4 %; iron dextran, 0.8 %; and iron sucrose, 10.2, 15.5, and 11.0 % (average, 12.2 %). The average Fe(II) content in iron sucrose was, therefore, ≥7.5-fold higher than in the other IV iron formulations. Further studies are needed to investigate the relationship between Fe(II) content and increased risk of oxidative stress and infections with iron sucrose.
authors.affiliation: Division of Nephrology, School of Medicine, University of California Irvine, 101 The City Drive South, City Tower, Suite 400, Orange, CA, 92868-3217, USA. ajayg1@uci.edu.|Rockwell Medical, Inc, Wixom, MI, USA. ajayg1@uci.edu.
authors.forename: Ajay
authors.initials: A
authors.lastname: Gupta
authors.affiliation: Rockwell Medical, Inc, Wixom, MI, USA.
authors.forename: Raymond D
authors.initials: RD
authors.lastname: Pratt
authors.affiliation: Department of Chemistry, Duke University, Durham, NC, USA.
authors.forename: Alvin L
authors.initials: AL
authors.lastname: Crumbliss
mesh_terms: D061605:Administration, Intravenous; D005290:Ferric Compounds / Q000008:administration & dosage / Q000737:chemistry*; D000077605:Ferric Oxide, Saccharated; D052203:Ferrosoferric Oxide / Q000008:administration & dosage / Q000737:chemistry*; D005296:Ferrous Compounds / Q000032:analysis*; D005937:Glucaric Acid / Q000008:administration & dosage / Q000737:chemistry*; D007505:Iron-Dextran Complex / Q000008:administration & dosage / Q000737:chemistry*; D008320:Maltose / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D005290:Ferric Compounds; D005296:Ferrous Compounds; C522335:ferric carboxymaltose; D008320:Maltose; D007505:Iron-Dextran Complex; D000077605:Ferric Oxide, Saccharated; D005937:Glucaric Acid; C035552:ferric gluconate; D052203:Ferrosoferric Oxide
keywords: Chronic hemodialysis; Ferric iron; Ferrous iron; Intravenous iron; Iron supplementation