Abstract
Since the first description of aluminum-related encephalopathy in patients on regular dialysis treatment, the toxicity of aluminum has been well recognized. Other aluminum-related diseases such as vitamin D-resistant osteomalacia and microcytic anemia have also been reported. In the present study, hydrous cerium oxide, a rare earth compound, was investigated as a new non-aluminum phosphate binder, Cerium oxide and hydroxyaluminum were mixed at the ratio of in a solution of phosphate compounds in which the phosphate ion concentration was 2.0mM, and the solution was stirred for one hour. Cerium and aluminum were also compared around the neutral range. The adsorptive effect of cerium oxide was one-fourth as great as that of hydroxyaluminum.
We tested the adsorptive effects of cerium oxide by using bovine blood 500ml, phosphate concentration 7.05mg/dl. Bovine blood was allowed to flow directly through a cerium oxide column. The adsorptive effect continued up to 90 minutes and the serum concentration reached zero at 120 minutes.
We also fed cerium oxide to partially (5/6) nephrectomied rats, chronic renal failure models, comparing it with hydroxyaluminum. In the cerium group, serum phoshate declined significantly from 7.02±0.92 (mg/dl) to 4.98±0.64 (mg/dl) (p<0.01) after two weeks' feeding, and in the aluminum group it also declined from 6.92±0.82 (mg/dl) to 5.24±0.70 (mg/dl). In conclusion, cerium oxide proved to have stronger adsorptive efficacy against phosphate ion than hydroxyaluminum.
A phosphate binder to take the place of aluminum gel is urgently needed, and cerium oxide is worth being studied and tested further.
