CHARACTERIZATION AND EXTRACORPOREAL APPLICATION OF A NEW PHOSPHATE-BINDING AGENT

A new phosphate-binding agent which does not cause any severe side eff ects in vivo was developed by modifying a crosslinked dextran with pol ynuclear iron(III)oxide-hydroxide. Its particle size ranges from 150 t o 300 mu m, and the iron content was about 18% by dry weight. The oxid ation state of iron was characterized by ESCA and Mossbauer spectrosco py. The maximum phosphate binding capacity of the iron(III)oxide-hydro xide-modified dextran was determined with respect to aqueous phosphate solutions, human serum and whole blood. The effects on whole blood co unt, haemolysis, protein concentration and enzyme activities were exam ined. In addition, the influence of phosphate concentration, pH and te mperature on the phosphate uptake of the material was determined. The results show that this new adsorbent might provide an alternative to c onventional phosphate-binding agents. This paper also describes the fi rst experiments on the therapeutic application of the material in an e xtracorporeal blood perfusion system for the treatment of hyperphospha taemia during haemodialysis.