Utilization of titanium oxide-like compound as an inorganic phosphate adsorbent for the control of serum phosphate level in chronic renal failure

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Hyperphosphatemia adversely affects the prognosis of patients with chronic renal failure (CRF). We synthesized a titanium oxide-like compound (TAP) as a phosphate adsorbent for treatment of hyperphosphatemia in CFR patients. We evaluated the ability of TAP to adsorb inorganic phosphate in vitro and in vivo. TAP was shown to contain sulfate and hydroxyl groups by thermal analysis, which probably involved in phosphate adsorption through an ionic exchange mechanism. TAP constantly adsorbed phosphate (66.20-72.84 mg/g TAP) over a wide pH range (1.22-7.27) in vitro. To evaluate the phosphate binding potential of TAP in vivo, adenine-induced CRF rats were fed AIN-76 diet containing 3% TAP, 10% TAP, 3% sevelamer hydrochloride (clinical phosphate adsorbent), or 3% calcium carbonate, and serum levels of phosphate and calcium and urinary phosphate were compared with those in untreated CRF rats. Orally administered TAP showed the inhibitory effect on serum phosphate level in adenine-induced CRF rats, which was equivalent to that of sevelamer hydrochloride. These results indicate that TAP is a useful alternative phosphate-binder with fewer side effects than sevelamer hydrochloride and calcium carbonate. J. Med. Invest. 57: 275-283, August, 2010