TENAPANOR: 1,935 Adverse Event Reports & Safety Profile

XPHOZAH (tenapanor) tablets contain tenapanor hydrochloride as an active ingredient. Tenapanor hydrochloride is a sodium/hydrogen exchanger 3 (NHE3) inhibitor for oral use. The chemical name for tenapanor hydrochloride is 12,15-Dioxa-2,7,9-triazaheptadecanamide, 17-[[[3-[(4S)-6,8-dichloro-1,2,3,4-tetrahydro-2-methyl-4-isoquinolinyl]phenyl]sulphonyl]amino]-N-[2-[2-[2-[[[3-[(4S)-6,8-dichloro-1,2,3,4-tetrahydro-2-methyl-4-isoquinolinyl]phenyl]sulphonyl]amino]ethoxy]ethoxy]ethyl]-8-oxo-, hydrochloride (1:2). Tenapanor hydrochloride has the molecular formula of C 50 H 68 Cl 6 N 8 O 10 S 2 , the molecular weight of 1218 Daltons, and the chemical structure below: Tenapanor hydrochloride is a white to off-white to light brown hygroscopic amorphous solid. It is practically insoluble in water. XPHOZAH tablets contain the equivalent of 10, 20, or 30 mg of tenapanor (provided as 10.6, 21.3, and 31.9 mg of tenapanor hydrochloride, respectively). Inactive ingredients in the tablet are colloidal silicon dioxide, low-substituted hydroxypropyl cellulose, microcrystalline cellulose, propyl gallate, stearic acid, tartaric acid, and the coating agent OPADRY ® , which consists of hypromellose, titanium dioxide and triacetin, as well as iron oxide yellow as colorant [10 mg and 20 mg tablets], iron oxide red as colorant [20 mg and 30 mg tablets] and iron oxide black as colorant [30 mg tablet].

Chemical

Structure

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 ).

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 <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.2) ]</span> . 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 <span class="opacity-50 text-xs">[see Warnings and Precautions (5.1) ]</span> . Instruct patients who miss a dose to skip the missed dose and take the next dose at the regular time.

XPHOZAH is contraindicated in patients under 6 years of age because of the risk of diarrhea and serious dehydration [see Warnings and Precautions (5.1) , Use in Specific Populations (8.5) ]. XPHOZAH is contraindicated in patients with known or suspected mechanical gastrointestinal obstruction. Pediatric patients under 6 years of age ( 4 ). Patients with known or suspected mechanical gastrointestinal obstruction ( 4 ).

REACTIONS Most common adverse reactions (≥2%) are diarrhea, abdominal distension, flatulence and dizziness. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Ardelyx at 1-844-427-7352 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1 Clinical Trials 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 1203 adult patients with IBS-C in two randomized, double-blind, placebo-controlled clinical trials (Trial 1 and Trial 2). Patients were randomized to receive placebo or IBSRELA 50 mg twice daily for up to 52 weeks. Demographic characteristics were comparable between treatment groups in the two trials <span class="opacity-50 text-xs">[see Clinical Studies (14) ]</span> .

Most Common Adverse Reactions

The most common adverse reactions reported in at least 2% of patients in IBSRELA-treated patients and at an incidence greater than placebo during the 26-week double-blind placebo-controlled treatment period of Trial 1 are shown in Table 1.

Table

1: Most Common Adverse Reactions Reported in at least 2% of patients in IBSRELA-treated patients and at an incidence greater than placebo in Patients with IBS-C in Trial 1 (26 Weeks)

Adverse

Reactions IBSRELA N=293 % Placebo N=300 % Diarrhea 16 4 Abdominal Distension 3 <1 Flatulence 3 1 Dizziness 2 <1 The adverse reaction profile was similar during the 12-week double-blind placebo-controlled treatment period of Trial 2 (610 patients: 309 IBSRELA-treated and 301 placebo-treated) with diarrhea (15% with IBSRELA vs 2% with placebo) and abdominal distension (2% with IBSRELA vs 0% with placebo) as the most common adverse reactions.

Adverse

Reaction of Special Interest – Severe Diarrhea Severe diarrhea was reported in 2.5% of IBSRELA-treated patients compared to 0.2% of placebo-treated patients during the 26 weeks of Trial 1 and the 12 weeks of Trial 2 [see Warnings and Precautions (5.2) ] . Patients with Renal Impairment In Trials 1 and 2, there were 368 patients (31%) with baseline renal impairment (defined as eGFR less than 90 mL/min/1.73m 2 ). In patients with renal impairment, diarrhea, including severe diarrhea, was reported in 20% (39/194) of IBSRELA-treated patients and 0.6% (1/174) of placebo-treated patients. In patients with normal renal function at baseline, diarrhea, including severe diarrhea, was reported in 13% (53/407) of IBSRELA-treated patients and 3.5% (15/426) of placebo-treated patients. No other differences in the safety profile were reported in the renally impaired subgroup. The incidence of diarrhea and severe diarrhea in IBSRELA-treated patients did not correspond to the severity of renal impairment.

Adverse Reactions

Leading to Discontinuation Discontinuations due to adverse reactions occurred in 7.6% of IBSRELA-treated patients and 0.8% of placebo-treated patients during the 26 weeks of Trial 1 and the 12 weeks of Trial 2. The most common adverse reaction leading to discontinuation was diarrhea: 6.5% of IBSRELA-treated patients compared to 0.7% of placebo-treated patients.

Less Common Adverse Reactions

Adverse reactions reported in less than 2% of IBSRELA-treated patients and at an incidence greater than placebo during the 26 weeks of Trial 1 and the 12 weeks of Trial 2 were: rectal bleeding and abnormal gastrointestinal sounds. Hyperkalemia In a trial of another patient population with chronic kidney disease (defined by eGFR from 25 to 70 mL/min/1.73m 2 ) and Type 2 diabetes mellitus, three serious adverse reactions of hyperkalemia resulting in hospitalization were reported in 3 patients (2 IBSRELA-treated patients and 1 placebo-treated patient).

6.2 Postmarketing Experience The following adverse reactions have been identified during post approval use of IBSRELA. 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

AND PRECAUTIONS Diarrhea: Patients may experience severe diarrhea. If severe diarrhea occurs, suspend dosing and rehydrate patient. ( 5.2 )

5.1 Risk of Serious Dehydration in Pediatric Patients IBSRELA is contraindicated in patients below 6 years of age. The safety and effectiveness of IBSRELA in patients less than 18 years of age have not been established. In young juvenile rats (less than 1 week old; approximate human age equivalent of less than 2 years of age), decreased body weight and deaths occurred, presumed to be due to dehydration, following oral administration of tenapanor. There are no data available in older juvenile rats (human age equivalent 2 years to less than 12 years). Avoid the use of IBSRELA in patients 6 years to less than 12 years of age. Although there are no data in older juvenile rats, given the deaths in younger rats and the lack of clinical safety and efficacy data in pediatric patients, avoid the use of IBSRELA in patients 6 years to less than 12 years of age <span class="opacity-50 text-xs">[see Contraindications (4) , Warnings and Precautions (5.2) , Use in Specific Populations (8.4) ]</span> .

5.2 Diarrhea Diarrhea was the most common adverse reaction in two randomized, double-blind, placebo-controlled trials of IBS-C. Severe diarrhea was reported in 2.5% of IBSRELA-treated patients <span class="opacity-50 text-xs">[see Adverse Reactions (6.1) ]</span> . If severe diarrhea occurs, suspend dosing and rehydrate patient.

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 <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.3) ]</span> . 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 <span class="opacity-50 text-xs">[see Clinical Pharmacology (12.3) ]</span> . However, the decrease in enalaprilat&apos;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.