Evaluation of the Physicochemical Properties of the Iron Nanoparticle Drug Products: Brand and Generic Sodium Ferric Gluconate.

Complex iron nanoparticle-based drugs are one of the oldest and most frequently administered classes of nanomedicines. In the US, there are seven FDA-approved iron nanoparticle reference drug products, of which one also has an approved generic drug product (i.e., sodium ferric gluconate (SFG)). These products are indicated for the treatment of iron deficiency anemia and are administered intravenously. On the molecular level, iron nanomedicines are colloids composed of an iron oxide core with a carbohydrate coating. This formulation makes nanomedicines more complex than conventional small molecule drugs. As such, these products are often referred to as nonbiological complex drugs (e.g., by the nonbiological complex drugs (NBCD) working group) or complex drug products (e.g., by the FDA). Herein, we report a comprehensive study of the physiochemical properties of the iron nanoparticle product SFG. SFG is the single drug for which both an innovator (Ferrlecit) and generic product are available in the US, allowing for comparative studies to be performed. Measurements focused on the iron core of SFG included optical spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), X-ray powder diffraction (XRPD), 57Fe Mössbauer spectroscopy, and X-ray absorbance spectroscopy (XAS). The analysis revealed similar ferric-iron-oxide structures. Measurements focused on the carbohydrate shell comprised of the gluconate ligands included forced acid degradation, dynamic light scattering (DLS), analytical ultracentrifugation (AUC), and gel permeation chromatography (GPC). Such analysis revealed differences in composition for the innovator versus the generic SFG. These studies have the potential to contribute to future quality assessment of iron complex products and will inform on a pharmacokinetic study of two therapeutically equivalent iron gluconate products.

Bioequivalence decision for nanoparticular iron complex drugs for parenteral administration based on their disposition.

Although parenteral iron products have been established to medicinal use decades before, their structure and pharmacokinetic properties are not fully characterized yet. With its' second reflection paper on intravenous iron-based nano-colloidal products (EMA/CHMP/SWP/620008/2012) the European Medicine Agency provided an extensive catalogue of methods for quality, non-clinical and pharmacokinetic studies for the comparison of nano-sized iron products to an originator (EMA, 2015). For iron distribution studies, the reflection paper assumed the use of rodents. In our tests, we used a turkey fetus model to investigate time dependent tissue concentrations in pharmacological and toxicological relevant tissues liver, heart and kidney. We found turkey embryos to be a suitable alternative to rodents with high discriminatory sensitivity. Clear differences were found between equimolar doses of iron products with hydroxyethyl amylopectin, sucrose, dextrane and carboxymaltose shell. A linear dose dependency for the tissue accumulation was also demonstrated.