Treatment
Following the screening period, patients were administered tenapanor orally at a starting dose of 5 mg twice daily, immediately before meals (breakfast and dinner) for 52 weeks in addition to phosphate binders at the dose administered at screening. The tenapanor dose could be adjusted in a stepwise manner from 5 mg to 10, 20, and 30 mg twice daily. The dose of tenapanor and phosphate binders was adjusted based on the most recent serum phosphorus level (Supplementary Fig. Aluminium preparations, niceritrol, nicotinamide, colestimide, cholestyramine, other supplements for phosphorus adsorption, anti-receptor activator of nuclear factor kappa-Β ligand antibody preparations, anti-sclerostin antibody preparations, and peritoneal dialysis were prohibited. Furthermore, the additional use or dose modification of drugs related to mineral metabolism was restricted, and changes in hemodialysis conditions were permitted when deemed necessary for the safety of patients.