Nanomedicines in clinical practice: Are colloidal iron sucrose ready-to-use intravenous solutions interchangeable?

The assessment of interchangeability of nanomedicines and nanosimilars is required for ensuring the safety, quality and efficacy of these complex drugs. Since 2011, regulatory agencies and researchers focused their attention on the characterization of iron sucrose, a colloidal solution parenterally used for the treatment of iron deficiency anemia, as well as on their follow-on versions, the so-called iron sucrose similars (ISSs). The purpose of this study was the evaluation of the size and size distribution of both IS and ISSs after dilution in polypropylene bags containing saline, mimicking the preparation of ready-to-use infusions to be administered in a hospital environment. The assays were carried out for 72 h, determining a general stability of the colloidal solutions investigated. Nevertheless, a dissimilar size and size distribution but also different visual appearance of IS and ISSs were recorded when the drugs diluted for therapeutic use. These results agree with previously published physicochemical and clinical data supporting the lack of exchangeability between IS and ISSs.