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Abstract: TH-PO147

Patient Education Improves Tenapanor Tolerability in OPTIMIZE Study

Session Information

Category: Bone and Mineral Metabolism

  • 502 Bone and Mineral Metabolism: Clinical


  • Fadem, Stephen Z., Kidney Associates, Houston, Texas, United States
  • Tietjen, David P., Nephrology Consultants, Huntsville, Alabama, United States
  • Spiegel, David M., Ardelyx, Inc., Waltham, Massachusetts, United States
  • Edelstein, Susan A., Ardelyx, Inc., Waltham, Massachusetts, United States
  • Yang, Yang, Ardelyx, Inc., Waltham, Massachusetts, United States
  • Rosenbaum, David P., Ardelyx, Inc., Waltham, Massachusetts, United States

Tenapanor (TEN) is a novel phosphate absorption inhibitor that blocks paracellular phosphate absorption by local inhibition of the intestinal sodium hydrogen exchanger isoform 3 (NHE3). TEN is being evaluated for the control of serum phosphate (sP) in adult patients (pts) with chronic kidney disease (CKD) on maintenance dialysis. TEN has demonstrated efficacy and acceptable safety in two pivotal monotherapy hyperphosphatemia clinical studies, BLOCK (NCT02675998) and PHREEDOM (NCT03427125). Diarrhea was the most common adverse event, observed in >5% of pts. Here, we evaluate the benefit of pt education on gastrointestinal tolerability during the OPTIMIZE (NCT04549597) study.


Methods for the trials have been previously described. The majority of patients were started on TEN at 30 mg bid. We assessed data from the analysis period in BLOCK (8-week treatment period [TP]), PHREEDOM (first 8 weeks of TP), and OPTIMIZE (10-week TP). In OPTIMIZE, pts were educated at study start about TEN, how to take TEN, what they may experience on TEN, medications to be discontinued before starting TEN, and how best to mitigate the potential onset of loose stools or diarrhea.


As expected, given the mechanism of action and data from past trials, most diarrhea events (75.7%–79.6%) occurred within the first 2 weeks of treatment in all three studies and the majority of cases were mild to moderate. Overall, the diarrhea incidence was lower during the analysis period in OPTIMIZE (39.3%) than in BLOCK and PHREEDOM (47.9% and 47.7%, respectively), and was also lower during the first two weeks of study treatment in OPTIMIZE (33.6%) vs BLOCK and PHREEDOM (38.0% and 39.4%). Discontinuation rates due to diarrhea were lower during the 10-week analysis period of OPTIMIZE (6.0%) than the 8-week analysis periods of BLOCK or PHREEDOM (7.0% and 13.4%).


Pt education may help ameliorate TEN-related diarrhea in dialysis pts. Specifically, since many pts on dialysis take medications to alleviate constipation, advising pts to discontinue these medications prior to starting TEN may also help reduce the occurrence of diarrhea.


  • Commercial Support – Ardelyx, Inc.