WALTHAM, Mass. — May 7, 2026 — Leads & Copy — Ardelyx, Inc. (Nasdaq: ARDX) presented data analysis on the long-term impact of XPHOZAH® (tenapanor) on serum electrolytes and nutrition biomarkers at the National Kidney Foundation’s (NKF) Spring Clinical Meetings in New Orleans.
XPHOZAH, a phosphate absorption inhibitor (PAI), is approved by the U.S. Food and Drug Administration for reducing serum phosphorus in adults with chronic kidney disease on dialysis. It is used as add-on therapy for patients who don’t respond adequately to phosphate binders or are intolerant to any dose of phosphate binder therapy.
According to Rajani Dinavahi, MD, Chief Medical Officer of Ardelyx, the post hoc analysis of the NORMALIZE and OPTIMIZE open-label clinical trials provides insight into the long-term safety of an XPHOZAH-based regimen for hyperphosphatemia patients on maintenance dialysis who were not controlled on binder therapy.
The analysis supports previous findings that tenapanor inhibition of the sodium hydrogen exchanger (NEH3) primarily affects serum phosphate concentrations. The poster, “Tenapanor Decreases Serum Phosphate Without Altering Other Serum Electrolytes in Patients with Chronic Kidney Disease with Hyperphosphatemia on Dialysis,” supports this analysis over an extended period.
Data from an 18-month extension study (NORMALIZE) and a 26-week study (OPTIMIZE) showed that tenapanor treatment resulted in no clinically meaningful changes in measured serum electrolyte concentrations, other than phosphate reduction. It also showed no significant changes in nutrition, body mass, or blood pressure.
These findings reinforce the safety data and effectiveness of tenapanor for managing serum phosphate in patients with chronic kidney disease and hyperphosphatemia on dialysis.
Poster presentations from the NKF Spring Clinical Meetings are available publicly on demand.
In addition to the poster presentation, Ardelyx is sponsoring a Peer Exchange on May 8 at 12:15 PM CT, titled “Treating Hyperphosphatemia and Side Effect Management.” Lisa Gutekunst, MSEd, RD, CSR, CDN, will lead a session discussing XPHOZAH, including its mechanism of action, efficacy and safety data, and practical considerations as add-on therapy for dialysis patients with serum phosphorus levels above guideline-established targets.
XPHOZAH (tenapanor) acts locally in the gut to inhibit the sodium hydrogen exchanger 3 (NHE3), reducing phosphate absorption through the paracellular pathway. It is administered as a single tablet taken twice daily. Diarrhea was the most common side effect reported in clinical trials.
The NORMALIZE study included patients completing the Phase 3 PHREEDOM trial. The study evaluated the ability of XPHOZAH alone or in combination with sevelamer to achieve serum phosphate levels within the normal range (2.5 to 4.5 mg/dL) in patients with CKD on maintenance dialysis whose serum phosphate levels were greater than 6.0 mg/dL at baseline.
The OPTIMIZE study was a randomized, open label study, which included 330 patients with chronic kidney disease (CKD) on dialysis with hyperphosphatemia. The study was designed to evaluate different methods of initiating XPHOZAH to optimize phosphorus management in both binder-naïve and binder-treated patients. The objective was to evaluate the ability of XPHOZAH, with its novel blocking mechanism, administered as core therapy for the treatment of hyperphosphatemia in adult patients with chronic kidney disease (CKD) on dialysis, alone or in combination with phosphate binders, to achieve target serum phosphorus (s-P) levels ≤5.5 mg/dL.
Hyperphosphatemia, or elevated phosphate levels in the blood, affects the majority of the 550,000 chronic kidney disease (CKD) patients on maintenance dialysis in the United States. The KDIGO treatment guidelines recommend lowering elevated phosphate levels toward the normal range (2.5-4.5mg/dL).
XPHOZAH is contraindicated in pediatric patients under 6 years of age and patients with known or suspected mechanical gastrointestinal obstruction.
Patients may experience severe diarrhea. Treatment with XPHOZAH should be discontinued in patients who develop severe diarrhea.
Diarrhea, which occurred in 43-53% of patients, was the only adverse reaction reported in at least 5% of XPHOZAH-treated patients with CKD on dialysis across trials. The majority of diarrhea events in the XPHOZAH-treated patients were reported to be mild-to-moderate in severity and resolved over time, or with dose reduction. Diarrhea was typically reported soon after initiation but could occur at any time during treatment with XPHOZAH. Severe diarrhea was reported in 5% of XPHOZAH-treated patients in these trials.
XPHOZAH (tenapanor), 30 mg BID, is indicated to reduce serum phosphorus in adults with chronic kidney disease (CKD) on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy.
Ardelyx is a commercial-stage biopharmaceutical company focused on developing and commercializing innovative medicines for unmet medical needs. Ardelyx has two commercial products approved in the United States, IBSRELA® (tenapanor) and XPHOZAH® (tenapanor). The company’s pipeline includes the Phase 3 development of IBSRELA for chronic idiopathic constipation (CIC) and RDX10531, a next-generation NHE3 inhibitor.
Source: Ardelyx
