Comment on Neiser et al. Assessment of Dextran Antigenicity of Intravenous Iron Preparations with Enzyme-Linked Immunosorbent Assay (ELISA). Int. J. Mol. Sci. 2016, 17, 1185.

All IV iron complexes carry a risk of potentially fatal allergic type hypersensitivity reactions. The mechanism(s) behind these reactions is unknown but the limited data available suggests that classic IgE mediated allergy is exceedingly rare, if ever occurring. Iron-carbohydrate molecules are complex nano-particles and trying to reduce the risk of serious hypersensitivity to antibody binding of an artificial antibody seems meaningless. A recently published analysis of safety data from randomized clinical trials confirms the method reported by Neiser to be useless to predict reaction risk. In conclusion, the study by Neiser et al. is biased, contains no new information, and has no clinical relevance. We are concerned that the association of the authors with a commercial entity has caused a conflict of interest that biases not only the results, but the entire experimental setup against competitors. (Comment on Neiser et al. Int. J. Mol. Sci. 2016, 17, 1185, doi:10.3390/ijms17071185).

Stable and high-yielding intrinsic (59) Fe-radiolabeling of the intravenous iron preparations Monofer and Cosmofer.

Commercial iron supplements Monofer(®) and Cosmofer(®) were intrinsically radiolabeled with (59) Fe for the purpose of tracing iron absorption in vivo. Optimized procedures aimed at introducing (59) Fe into the macromolecular construct in a form that was as chemically equivalent to the matrix iron as possible. This was determined by challenging the labeled constructs with diethylenetriaminepentaacetic acid (DTPA) followed by separation by size-exclusion and measurements of radioactivity and iron in the eluted fractions. The final procedures were simple and involved heating aqueous dispersions of the supplements in the presence of [(59) Fe]FeCl3 for 24 h at 95 °C for Monofer, and 85 °C for Cosmofer, resulting in radiochemical yields greater than 94%. High performance size exclusion chromatography, UV-VIS spectroscopy, and dynamic light scattering were used to show that the supplements remained unchanged after radiolabeling, underscoring the applicability of the methodology for radiolabeling commercial iron preparations.

Pharmacokinetics of iron isomaltoside 1000 in patients with inflammatory bowel disease.

BACKGROUND: Iron isomaltoside 1000 is a novel injectable iron compound which offers potential advantages in the treatment of subjects with iron-deficiency anemia. We studied the pharmacokinetics (PK) of this novel compound in subjects with mild-to-moderate inflammatory bowel disease (IBD). METHODS: This open-label, crossover, single-center trial was conducted in 12 subjects with IBD who were allocated to one of the two single intravenous (IV) bolus sequences of iron isomaltoside 1000: 100 mg followed by 200 mg, or vice-versa. PK variables were analyzed according to a single-compartment model. RESULTS: The concentration-versus-time relationship for isomaltoside-bound iron (IBI) and total iron (TI) showed first-order kinetics with small deviations from dose-linearity. The area under the concentration-time curve (AUC) values in h * µg/mL for IBI following 100 mg and 200 mg doses were 888 and 2141 respectively, and for TI following 100 mg and 200 mg doses, the AUC values were 1010 and 2319 respectively. The corresponding maximum serum concentration (C(max)) values in µg/mL were 35.6 and 68.6 for IBI, and 37.3 and 71.1 for TI. The half-life (T(½)) values for IBI and TI were between 20.8-23.5 hours. The apparent volume of distribution (V(D)) ranged from 3.0-3.5 L. Only approximately 1% of the doses administered were excreted in the urine. No serious adverse event (SAE) was reported. One subject was withdrawn after the 100 mg dose due to abdominal pain and flushing. CONCLUSION: At the administered doses, iron isomaltoside 1000 showed first-order PK, and did not raise safety concerns in patients with IBD. The PK parameters for IBI were close to those of TI.

A comparative study of the physicochemical properties of iron isomaltoside 1000 (Monofer), a new intravenous iron preparation and its clinical implications.

The treatment of iron deficiency anemia with polynuclear iron formulations is an established therapy in patients with chronic kidney disease but also in other disease areas like gastroenterology, cardiology, oncology, pre/post operatively and obstetrics' and gynecology. Parenteral iron formulations represent colloidal systems in the lower nanometer size range which have traditionally been shown to consist of an iron core surrounded by a carbohydrate shell. In this publication, we for the first time describe the novel matrix structure of iron isomaltoside 1000 which differs from the traditional picture of an iron core surrounded by a carbohydrate. Despite some structural similarities between the different iron formulations, the products differ significantly in their physicochemical properties such as particle size, zeta potential, free and labile iron content, and release of iron in serum. This study compares the physiochemical properties of iron isomaltoside 1000 (Monofer) with the currently available intravenous iron preparations and relates them to their biopharmaceutical properties and their approved clinical applications. The investigated products encompass low molecular weight iron dextran (CosmoFer), sodium ferric gluconate (Ferrlecit), iron sucrose (Venofer), iron carboxymaltose (Ferinject/Injectafer), and ferumoxytol (Feraheme) which are compared to iron isomaltoside 1000 (Monofer). It is shown that significant and clinically relevant differences exist between sodium ferric gluconate and iron sucrose as labile iron formulations and iron dextran, iron carboxymaltose, ferumoxytol, and iron isomaltoside 1000 as stable polynuclear formulations. The differences exist in terms of their immunogenic potential, safety, and convenience of use, the latter being expressed by the opportunity for high single-dose administration and short infusion times. Monofer is a new parenteral iron product with a very low immunogenic potential and a very low content of labile and free iron. This enables Monofer, as the only IV iron formulation, to be administered as a rapid high dose infusion in doses exceeding 1000 mg without the application of a test dose. This offers considerable dose flexibility, including the possibility of providing full iron repletion in a single infusion (one-dose iron repletion).