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Abstract: PO0544

Impact of Tenapanor in Peritoneal Dialysis

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Rosenbaum, David P., Ardelyx Inc, Fremont, California, United States
  • Finkelstein, Fredric O., Yale-New Haven Hospital, New Haven, Connecticut, United States
  • Yang, Yang, Ardelyx Inc, Fremont, California, United States
  • Galvin, Rebecca, Ardelyx Inc, Fremont, California, United States
  • Spiegel, David M., Ardelyx Inc, Fremont, California, United States
Background

Peritoneal dialysis (PD) utilization is being promoted worldwide as more emphasis is placed on the advantages and reduced cost of home dialysis. Serum phosphorus (sP) control for PD patients remains a challenge, particularly as residual kidney function is lost. Many PD patients receive stool softeners or laxatives to prevent constipation which may impede the treatment. Tenapanor (TEN) is a first-in-class phosphate absorption inhibitor (PAI) that targets the paracellular pathway of phosphate absorption by inhibiting the sodium-hydrogen exchanger 3 (NHE3) antiporter on the luminal surface of gastrointestinal epithelium. As a side effect of inhibiting NHE3, the sodium and water content of the stool is augmented, increasing stool frequency and volume. Here we compare the control of sP and the adverse event (AE) profile of TEN in the PD and hemodialysis (HD) subgroups in the phase 3 PHREEDOM trial.

Methods

PHREEDOM evaluated the safety and efficacy of TEN in patients on HD or PD with hyperphosphatemia. Following washout from phosphate binders, patients whose sP increased by 1.5 to ≥6.0 mg/dL were enrolled. Those randomized to the TEN arm received TEN 30 mg orally twice daily for 26 weeks. Counseling to discontinue stool softeners or laxatives was not provided to patients entering the trial. sP and AEs were recorded per protocol.

Results

Over the 26-week treatment period, the change in sP was similar for patients treated by PD (n=42) and HD (n=365) (figure). Diarrhea was the most common AE (56.1%) in the PD subgroup (with a similar incidence in the HD subgroup [51.6%]); no PD patients reported diarrhea as a serious AE.

Conclusion

These findings demonstrate that TEN may be a useful agent in reducing sP levels for patients treated with PD and have an added benefit of assisting with the management of constipation, which can be problematic for the PD patient. Prior counseling to discontinue stool softeners and laxatives when initiating TEN may decrease the AE of diarrhea and further reduce the number of medications when patients are switched from phosphate binders to TEN.

Funding

  • Commercial Support