Phosphate-binding capacities of calcium and aluminum formulations.

Calcium and aluminum phosphate binders are used to treat hyperphosphatemia which is responsible for the development of osteodystrophy commonly seen in patients with end-stage renal disease. The purpose of this study was to determine the phosphate binding capacities of several frequently used calcium and aluminum formulations. The effect of formulation types on phosphate binding was evaluated. Calcium and aluminum phosphate binders were administered to six healthy volunteers after phosphate load on separate study days. Total urine outflow was collected afterwards to determine the amount of phosphate recovered, which indicates the ability of the phosphate binder to reduce gastrointestinal phosphate absorption. The amounts of urinary phosphate recovered were different after administration of the phosphate binders. Calcium acetate resulted in the least amount of phosphate excreted. Calcium carbonate suspension, when compared with the tablet formulation, caused a smaller amount of phosphate excreted in the urine. Different phosphate binders formulations were found to have different phosphate binding capacities. Patients should therefore be closely monitored for efficacy after switching from one phosphate binder to another.