Best practice for the size analysis of nanomedicines – An iron sucrose case study

Iron sucrose is used in the parenteral treatment of iron deficiency anaemia. A number of iron sucrose similars have been developed alongside the original product. These products consist of colloidal iron with particles in the nanometre range stabilised by sucrose molecules. Dynamic light scattering (DLS) is the method of choice for the qualification of iron sucrose products in terms of particle size. However, the broad range of instrumentation and accessories available today for the execution of these measurements requires that best laboratory practice is established to ensure measurement comparability and consistent product quality. In this work, we have examined the measurement of iron sucrose particle size by DLS using a range of instrument models and manufacturers and compared results. We performed transmission electron microscopy with cryogenic capability to support DLS data interpretation. We find that DLS results are consistent when equivalent settings are selected across instruments, we discuss the experimental parameters of importance for high-quality measurements and present preliminary data for emerging modalities. Although focussed on iron sucrose products, the outcome of this work is relevant to the analysis of other types of nanoparticle-based products.