CROSS-LINKED IRON DEXTRAN IS AN EFFICIENT ORAL PHOSPHATE BINDER IN THE RAT

Background. There is a need for alternative oral phosphate binders. In -vitro studies showed that iron(III) oxide-hydroxide-modified cross-li nked dextran is a promising, insoluble phosphate-binding agent. The pr esent study was designed to assess its in-vivo efficacy and safety in the rat. Study, design and methods. Iron(III) oxide-hydroxide modified dextran beads were mixed with normal rat feed in a proportion of 8% b y weight. With this formula rats were fed for 4 weeks. A control group received the same diet without added phosphate binder. Samples of blo od, urine, and faeces were taken from each animal before the phosphate binder was administered, 2 weeks later, and at the end of the examina tion period (day 29). Phosphate, calcium, iron were analysed in the bl ood samples. Calcium and phosphate concentrations were determined in t he urine, phosphate, calcium, and iron concentrations in the excrement s. Stability of the material in the duodenum was also simulated. Resul ts and conclusions. The results demonstrate an excellent phosphate-bin ding capacity of the material and a good tolerance during the intestin al passage. No significant chemical or enzymatic degradation, histolog ical alterations, or other treatment-related macroscopic findings were recorded. The present efficacy and toxicity study has shown effective phosphate binding with no toxicity and no iron release after ingestio n of this novel phosphate binding agent. We propose clinical evaluatio n studies to assess whether similar efficacy and safety can be shown i n humans.