Comparison of early gastrointestinal tract and liver toxicity of the originator iron polymaltose complex (IPC) and an IPC similar preparation in non-anemic rats

Abstract

Objectives: The originator iron polymaltose complex (Maltofer®, IPC, Vifor International, St. Gallen, Switzerland) has been used for over 30 years to treat iron deficiency anemia. Its physico-chemical properties allow for a controlled release of iron, a property which translates into low toxicity and good gastrointestinal (GI) tolerability of the drug compared to the commonly used ferrous salts. A variety of different iron polymaltose complex similars are commercially available with varying structures and, thus, different efficacy and toxicity compared to IPC. In this study, the median lethal dose, the GI tract and liver toxicity of an IPC similar (Vitalix®, IPCSVITA, Laboratorios Roemmers, Buenos Aires, Argentina) were compared with those of IPC in healthy rats. Methods: The median lethal dose of IPCSVITA was determined as the dose required to kill 6 out of 12 rats after 24 h from dosing. To compare the GI and liver toxicities, rats received IPCSVITA or IPC (both 280 mg iron/kg body weight) for 28 days. GI toxicity was assessed macroscopically by scoring lesion severities and microscopically by analyzing the villi/crypt ratio, number of eosinophils/villi and number of Goblet cells/villi. Ferritin was assessed in the small intestine villi and in the liver by immunostaining. Iron deposits in the liver were assessed by Prussian blue staining. Results: Serum iron concentration and transferrin saturation (TSAT) were significantly higher in the IPCSVITA group vs. the IPC and the control groups. Food consumption, body weight, and bowel movement at Day 29 were significantly lower within the IPCSVITA group vs. the IPC or the control groups. The lesion scores in the stomach and in the lower GI tract of the IPCSVITA group were significantly higher than those of the IPC and control groups. The villi/crypt ratio and the number of Goblet cells/villi in the small intestine were significantly lower in IPCSVITA-treated animals than in IPC-treated or control animals. The number of eosinophils per villi was significantly increased in the IPCSVITA group vs. IPC and control group. In the lower GI tract, microscopic lesions were observed only in the IPCSVITA group. The amount of ferritin in the small intestine and in the liver was higher in IPC-treated animals vs. IPCSVITA- treated or control animals. Conclusions: Higher serum iron and TSAT levels, lesions in the stomach and lower GI tract suggest the presence of weakly bound iron on the surface of the IPCSVITA complex, which has different physico-chemical properties than IPC. The lower levels of iron deposits in the liver suggest that the iron from IPCSVITA is taken up in a less controlled way than from IPC, thus, potentially accumulating in the wrong cellular compartment.