Tenapanor

7 DRUG INTERACTIONS OATP2B1 Substrates: Potential for reduced exposure of the concomitant drug (e.g., enalapril). Monitor for signs related to loss of efficacy and adjust the dosage of the concomitantly administered drug as needed ( 7.1 ). Sodium Polystyrene Sulfonate (SPS): Separate administration by at least three hours ( 7.2 ). 7.1 OATP2B1 Substrates Tenapanor is an inhibitor of intestinal uptake transporter, OATP2B1 [see Clinical Pharmacology (12.3) ] . Drugs which are substrates of OATP2B1 may have reduced exposures when concomitantly taken with XPHOZAH. Monitor for signs related to loss of efficacy and adjust the dose of concomitantly administered drug as needed. Enalapril is a substrate of OATP2B1. When enalapril was coadministered with XPHOZAH (30 mg twice daily for five days), the peak exposure (C max ) of enalapril and its active metabolite, enalaprilat, decreased by approximately 70% and total systemic exposures (AUC) decreased by 50 to 65% compared to when enalapril was administered alone [see Clinical Pharmacology (12.3) ] . However, the decrease in enalaprilat's exposure with XPHOZAH may be offset by the inherently higher exposures observed in patients with CKD on dialysis due to its reduced renal clearance. Therefore, a lower starting dose of enalapril, which is otherwise recommended in patients with CKD on dialysis is not required when enalapril is coadministered with XPHOZAH. 7.2 Sodium Polystyrene Sulfonate Separate administration of XPHOZAH and sodium polystyrene sulfonate (SPS) by at least 3 hours. SPS binds to many commonly prescribed oral medicines.

1 INDICATIONS AND USAGE XPHOZAH 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. XPHOZAH is a sodium hydrogen exchanger 3 (NHE3) inhibitor 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 ( 1 ).

2 DOSAGE AND ADMINISTRATION Recommended dosage: 30 mg orally twice daily before the morning and evening meals ( 2.1 ). Manage serum phosphorus levels and tolerability with dosage adjustments ( 2.1 ). Take just prior to the first and last meals of the day ( 2.2 ). Instruct patients not to take right before a hemodialysis session, and instead take right before the next meal following dialysis ( 2.2 ). 2.1 Recommended Dosage The recommended dosage is 30 mg orally twice daily before the morning and evening meals. Monitor serum phosphorus and adjust the dosage as needed to manage gastrointestinal tolerability. 2.2 Administration Instructions Instruct patients to take XPHOZAH just prior to the first and last meals of the day [see Clinical Pharmacology (12.2) ] . Instruct patients not to take XPHOZAH right before a hemodialysis session, and instead take right before the next meal following dialysis, as patients may experience diarrhea after taking XPHOZAH [see Warnings and Precautions (5.1) ] . Instruct patients who miss a dose to skip the missed dose and take the next dose at the regular time.

6 ADVERSE REACTIONS Most common adverse reaction in the combined clinical trials was diarrhea, reported by 43-53% of patients ( 6 ). To report SUSPECTED ADVERSE REACTIONS, contact Ardelyx at 1-844-974-6924 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety data described below reflect data from 754 adults with CKD on dialysis taking XPHOZAH in clinical trials as monotherapy and in combination with phosphate binders. Among the 754 patients, 258 patients were exposed to tenapanor for at least 26 weeks and 75 were exposed to tenapanor for at least one year. [see Clinical Studies (14) ] . Most Common Adverse Reaction 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 [see Warnings and Precautions (5.1) ] . 6.2 Postmarketing Experience The following adverse reactions have been identified during post approval use of XPHOZAH. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Hypersensitivity reactions: pruritis, rash, and urticaria