Effect of Tenapanor on Phosphate Binder Pill Burden in Hemodialysis Patients

INTRODUCTION: The current management of hyperphosphatemia with phosphate binders is associated with insufficient phosphorus control and a significant pill burden. Tenapanor, a first-in-class, phosphate absorption inhibitor, is expected to control phosphorus and decrease pill burden because of its small pill size and twice daily dosing regimen. This study evaluated tenapanor effectiveness on reducing the phosphate binder pill burden during a 26-week treatment period in Japanese hemodialysis patients. METHODS: In this multicenter, open-label, single-arm study, hemodialysis patients whose serum phosphorus level was 3.5 to 7.0 mg/dl received tenapanor 30 mg twice daily orally added to their phosphate binder regimen. The phosphate binder dosage was adjusted to achieve a serum phosphorus level within the baseline range of ±0.5 mg/dl. The primary end point was the percentage of patients who achieved a ≥30% decrease in the number of phosphate binders and tenapanor tablets prescribed daily compared with the number of phosphate binder tablets at baseline. RESULTS: Of the 67 patients enrolled, 43 completed the study. At baseline, the mean total number of phosphate binder tablets per day was 14.7, which decreased to 3.0 tablets per day at week 26. The primary end point was achieved in 71.6% of patients (P < 0.001). The phosphate binder was completely switched to tenapanor in 28.4% of patients (P < 0.001). The mean phosphorus levels were relatively well controlled (5.19 and 4.71 mg/dl at baseline and week 26, respectively). The most frequent drug-related adverse event (AE) was diarrhea (74.6%). CONCLUSION: Tenapanor provided effective phosphorus control and decreased the number of phosphate binder tablets. The management of drug-related diarrhea will facilitate more widespread use of tenapanor.