Study to Evaluate the Efficacy of Tenapanor as Adjunctive Therapy to Phosphate Binder Therapy

Inclusion Criteria

• •Signed and dated informed consent prior to any study specific procedures.
• •Males or females aged 18 to 80 years, inclusive, at Screening
• •Females must be non-pregnant, non-lactating and either be post-menopausal for at least -2 months, have documentation of irreversible surgical sterilization, use of acceptable -contraceptive method, or sexual abstinence, or a sterile sexual partner from Screening -until 30 days after the last subject visit.
• •Males must agree to avoid fathering a child (or donating sperm), and therefore be either sterile (documented) or agree to use approved methods of contraception, from the time of enrollment until 30 days after end of study.
• •Chronic maintenance hemodialysis (HD) 3x/week for at least 3 months or chronic maintenance peritoneal dialysis (PD) for a minimum of 6 months.
• •If receiving active vitamin D or calcimimetics, the dose should have been unchanged for the last 4 weeks prior to Screening.
• •Kt/V ≥1.2 at most recent measurement prior to Screening.
• •Prescribed and taking phosphate binder medication at least 3 times per day, and the prescribed dose should have been unchanged during the last 4 weeks prior to Screening.
• •Serum phosphorus levels must be ≥5.5 and ≤10.0 mg/dL at Screening and the end of the run-in period, analyzed at the central laboratory used in the study.