Tenapanor Reduces Elevated Serum Phosphate in CKD

Adverse events limited to softened stool, modest increase in bowel movement freqeuncy

FRIDAY, March 8, 2019 (HealthDay News) -- For hyperphosphatemic patients with chronic kidney disease receiving maintenance hemodialysis, tenapanor significantly reduces elevated serum phosphate, according to a study published online March 7 in the Journal of the American Society of Nephrology.

Geoffrey A. Block, M.D., from Denver Nephrology, and colleagues conducted a phase 3 randomized trial involving hyperphosphatemic patients undergoing maintenance hemodialysis who received twice-daily oral tenapanor (3, 10, or 30 mg) for eight weeks. Patients were then randomly assigned to receive their previously assigned dose or placebo for a withdrawal period of four weeks.

Two hundred nineteen patients were randomly assigned; 152 completed both phases. The researchers found that all three treatment groups experienced significant decreases in mean serum phosphate during the initial eight-week treatment period (reductions of 1.00, 1.02, and 1.19 mg/dL, respectively). During the withdrawal period, tenapanor also showed a significant benefit over placebo, with a mean increase in the serum phosphate level of 0.85 versus 0.02 mg/dL in the placebo group versus the pooled tenapanor group. Adverse events were mainly limited to softened stool and a modest increase in the frequency of bowel movements.

"I am extremely excited about the therapeutic potential of tenapanor in patients with advanced chronic kidney disease," a coauthor said in a statement. "Tenapanor is not a phosphate binder, but rather, a novel agent that inhibits the intestinal absorption of phosphorus."

All study authors disclosed financial ties to Ardelyx, which manufactures tenapanor and funded the study.

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