August 1, 2012

Phosphate Binders May Have Undesired Effects in CKD Sufferers

Washington, D.C.—Phosphate binders used to treat chronic kidney disease (CKD) not only are less effective than once believed, but they can potentially harm blood vessels.

That's according to a new study published online by Journal of the American Society of Nephrology (JASN). The authors are calling for additional studies on the drugs.

Phosphate binders, which are used to lower blood phosphorus levels, are approved only for patients with kidney failure. They often are prescribed off-label for patients with CKD, who can suffer heart problems, kidney disease, and premature death with phosphorus levels that are higher but still fall into the normal range.

Researchers evaluated the effects of calcium acetate, lanthanum carbonate, and sevelamer carbonate in 148 patients with moderate to advanced CKD and normal or near normal blood phosphorus levels. The patients were randomized to receive either one of the three phosphate binders or a placebo.

In the study, the longest placebo-controlled trial of phosphate binders in patients with CKD, the patients were examined after 3, 6, and 9 months of treatment.

While treatment with phosphate binders significantly lowered patients' urinary phosphorus levels, moderately lowered their blood phosphorus levels, and slowed progression of a parathyroid disorder that is a common complication of CKD, it did not have any effect on the blood levels of a hormone that regulates phosphate excretion in the urine. Furthermore, with heart disease the leading cause of death in patients with CKD, the drugs caused calcium to buildup in blood vessels.

"While we continue to believe that serum, or blood, phosphorus is a key component of the increased cardiovascular risk associated with kidney disease, our results suggest the use of the currently approved phosphate binding drugs does not result in substantial reductions in serum phosphorus and may be associated with harm in this population," said lead author Geoffrey A. Block, MD, of Denver Nephrology. "Future clinical trials should be conducted in all populations with adequate placebo controls and should address alternative or complementary methods to reduce serum phosphorus."

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