The Use of Magnetic Resonance Imaging for Non-Invasive Assessment of Venofer® Biodistribution in Rats.

PURPOSE: The aim of this study was to determine the potential of magnetic resonance imaging to evaluate the biodistribution of exogenous iron within 24 h after one single injection of Venofer® (iron sucrose). METHODS: Venofer® was evaluated in vitro for its ability to generate contrast in MR images. Subsequently, iron disposition was assessed in rats with MRI, in vivo up to 3 h and post mortem at 24 h after injection of Venofer®, at doses of 10- and 40 mg/kg body weight (n = 2 × 4), or saline (n = 4). RESULTS: Within 10-20 min after injection of Venofer®, transverse relaxation rates (R2) clearly increased, representative of a local increase in iron concentration, in liver, spleen and kidney, including the kidney medulla and cortex. In liver and spleen R2 values remained elevated up to 3 h post injection, while the initial R2 increase in the kidney was followed by gradual decrease towards baseline levels. Bone marrow and muscle tissue did not show significant increases in R2 values. Whole-body post mortem MRI showed most prominent iron accumulation in the liver and spleen at 24 h post injection, which corroborated the in vivo results. CONCLUSIONS: MR imaging is a powerful imaging modality for non-invasive assessment of iron distribution in organs. It is recommended to use this whole-body imaging approach complementary to other techniques that allow quantification of iron disposition at a (sub)cellular level.

Evaluation of the suitability of a Sprague Dawley rat model to assess intravenous iron preparations.

The aim of the study was to examine the reproducibility of a rat model to assess the preclinical similarity in safety profiles and tissue accumulation of iron products. Accordingly, the effect of several doses of intravenously administered Venofer® and of Ferrlecit® on blood parameters, and on kidney and particularly liver toxicity were examined in non-anemic Sprague Dawley rats. The different analysis showed neither a clear treatment nor a dose effect after multiple injections. The parameters measured in this rat strain showed some iron induced adverse effects, but these could not be correlated to treatment specific differences. The findings presented in this paper indicate the difficulty to define a useful preclinical model to evaluate iron-based nano-colloidal preparations.

A novel oral iron-complex formulation: Encapsulation of hemin in polymeric micelles and its in vitro absorption.

Anemia resulting from iron deficiency is one of the most prevalent diseases in the world. As iron has important roles in several biological processes such as oxygen transport, DNA synthesis and cell growth, there is a high need for iron therapies that result in high iron bioavailability with minimal toxic effects to treat patients suffering from anemia. This study aims to develop a novel oral iron-complex formulation based on hemin-loaded polymeric micelles composed of the biodegradable and thermosensitive polymer methoxy-poly(ethylene glycol)-b-poly[N-(2-hydroxypropyl)methacrylamide-dilactate], abbreviated as mPEG-b-p(HPMAm-Lac2). Hemin-loaded micelles were prepared by addition of hemin dissolved in DMSO:DMF (1:9, one volume) to an aqueous polymer solution (nine volumes) of mPEG-b-p(HPMAm-Lac2) followed by rapidly heating the mixture at 50°C to form hemin-loaded micelles that remain intact at room and physiological temperature. The highest loading capacity for hemin in mPEG-b-p(HPMAm-Lac2) micelles was 3.9%. The average particle diameter of the hemin-micelles ranged from 75 to 140nm, depending on the concentration of hemin solution that was used to prepare the micelles. The hemin-loaded micelles were stable at pH 2 for at least 3 h which covers the residence time of the formulation in the stomach after oral administration and up to 17 h at pH 7.4 which is sufficient time for uptake of the micelles by the enterocytes. Importantly, incubation of Caco-2 cells with hemin-micelles for 24 h at 37°C resulted in ferritin levels of 2500ng/mg protein which is about 10-fold higher than levels observed in cells incubated with iron sulfate under the same conditions. The hemin formulation also demonstrated superior cell viability compared to iron sulfate with and without ascorbic acid. The study presented here demonstrates the development of a promising novel iron complex for oral delivery.