Ardelyx Presents Real-World Data at ACG 2026 Showing Reduced Healthcare Resource Utilization Following IBSRELA® Initiation in Adults with IBS-C

WALTHAM, Mass., Oct. 12, 2026 (ZM NEWSWIRE) — Ardelyx, Inc. (Nasdaq: ARDX), a commercial-stage biopharmaceutical company focused on the development and commercialization of innovative medicines that meet significant unmet medical needs, today announced results from a real-world analysis being presented at the American College of Gastroenterology (ACG) 2026 Annual Scientific Meeting showing that gastrointestinal-related healthcare resource utilization (GI-HCRU) dropped significantly after adults with irritable bowel syndrome with constipation (IBS-C) started IBSRELA® (tenapanor). Ardelyx will also present data on how IBS-C symptom burden affects quality of life, along with the design and rationale of an ongoing Phase 3 study evaluating tenapanor in adults with chronic idiopathic constipation (CIC).

“IBS-C can affect patients in ways that extend well beyond their symptoms, placing a significant burden on daily life and quality of life, including through ongoing interactions with the healthcare system. We are encouraged by these real-world findings, which show a significant reduction in GI-related healthcare utilization following IBSRELA initiation,” said Rajani Dinavahi, MD, Chief Medical Officer of Ardelyx. “Together with our additional data presented at ACG, these findings reflect our commitment to generating evidence that deepens our understanding of constipation-related disorders, helps inform patient care, and supports continued research into the potential role of tenapanor beyond IBS-C.”

The data comes from a retrospective, observational real-world analysis of 470 patients with IBS-C who started tenapanor at a national gastroenterology practice. A significant reduction in median GI-related HCRU was observed, from 4.5 visits in the year before tenapanor initiation to 3.0 visits in the year following initiation (3.0 [IQR: 1, 6] vs. 4.5 [IQR: 2, 9]; P<0.001). Significant reductions were also seen in subgroup analyses among patients who had previously tried at least one IBS-C medication, regardless of BMI or comorbidity burden.

Presentations at ACG 2026 include:

Presentation Title	Authors	Poster Number	Presentation Details
Health Care Resource Utilization Decreases Among Patients with Constipation Predominant Irritable Bowel Syndrome Following Initiation of Tenapanor: A Real-World Analysis	Kyle Staller, Alan Fossa, Megan O’Byrne, Luisa L. Scott	#P3082	Poster, Oct 12, 1:00 – 2:15 PM CT
A Phase 3, 26-Week Randomized Controlled Study to Assess Safety and Efficacy of Tenapanor for Treatment of Chronic Idiopathic Constipation in Adults: Design and Rationale	Susan Edelstein, Yang Yang, Jocelyn M. Tabora, Kenji Kozuka, Karishma Raju, Anthony J. Lembo.	#P5352	Poster, Oct 13, 1:00 – 2:15 PM CT
High Symptom Severity Burden is Associated with Reduced Quality of Life in US Adults with Irritable Bowel Syndrome with Constipation	Megan Riehl, Taya Westfield, Alan Fossa, Zachary Babcock, Johannah Ruddy, Luisa L. Scott	#P5327	Poster, Oct 13, 1:00 – 2:15 PM CT

In addition to the poster presentations during ACG, Ardelyx is sponsoring a Product Theater titled “Expanding IBS-C Care with a First-in-Class Treatment,” on October 12th at 2:30 PM CT, where Dr. Aja McCutchen will lead an engaging clinical discussion on managing adult patients with IBS-C. The session will explore the pathophysiology of IBS-C, examine patient case studies, and discuss practical strategies for identifying when and how to optimize care for patients who may not be achieving adequate symptom relief.

About IBSRELA® (tenapanor)

IBSRELA® (tenapanor) is a locally acting inhibitor of the sodium/hydrogen exchanger 3 (NHE3), an antiporter expressed on the apical surface of the small intestine and colon that is primarily responsible for the absorption of dietary sodium. By inhibiting NHE3, tenapanor reduces the absorption of sodium from the small intestine and colon, retaining luminal water content, accelerating intestinal transit time and resulting in a softer stool consistency. IBSRELA has also been shown to reduce abdominal pain by decreasing visceral hypersensitivity and intestinal permeability in animal models. Please see additional full Prescribing Information.

About Irritable Bowel Syndrome with Constipation (IBS-C)

Irritable bowel syndrome with constipation (IBS-C) is a gastrointestinal disorder characterized by abdominal pain and altered bowel movements, estimated to affect 12 million people in the U.S. People living with IBS-C may experience a range of symptoms, including abdominal pain, bloating and infrequent, hard or difficult-to-pass stools. IBS-C can have a significant impact on daily life and is associated with impaired quality of life, reduced productivity, and substantial economic burden.

IMPORTANT SAFETY INFORMATION (IBSRELA)

WARNING: RISK OF SERIOUS DEHYDRATION IN PEDIATRIC PATIENTS IBSRELA is contraindicated in patients less than 6 years of age; in nonclinical studies in young juvenile rats administration of tenapanor caused deaths presumed to be due to dehydration. Avoid use of IBSRELA in patients 6 years to less than 12 years of age. The safety and effectiveness of IBSRELA have not been established in patients less than 18 years of age.

CONTRAINDICATIONS

• IBSRELA is contraindicated in patients less than 6 years of age due to the risk of serious dehydration.
• IBSRELA is contraindicated in patients with known or suspected mechanical gastrointestinal obstruction.

WARNINGS AND PRECAUTIONS
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.

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. If severe diarrhea occurs, suspend dosing and rehydrate patient.

MOST COMMON ADVERSE REACTIONS
The most common adverse reactions in IBSRELA-treated patients (incidence ≥2% and greater than placebo) were: diarrhea (16% vs 4% placebo), abdominal distension (3% vs <1%), flatulence (3% vs 1%) and dizziness (2% vs <1%).

INDICATION
IBSRELA (tenapanor) is indicated for the treatment of Irritable Bowel Syndrome with Constipation (IBS-C) in adults.

Please see full Prescribing Information, including Boxed Warning, for additional risk information.

About Ardelyx

Ardelyx is a commercial-stage biopharmaceutical company focused on the development and commercialization of innovative medicines that meet significant unmet medical needs. Ardelyx has two commercial products approved in the United States, IBSRELA® (tenapanor) and XPHOZAH® (tenapanor). The company’s pipeline includes the Phase 3 development of IBSRELA for chronic idiopathic constipation (CIC) and RDX10531, a next-generation NHE3 inhibitor with potential application across multiple therapeutic areas. Ardelyx works with its partners to develop and commercialize its products outside of the United States. For more information, please visit https://ardelyx.com/ and connect with us on X (formerly known as Twitter), LinkedIn and Facebook.

Forward-Looking Statements

To the extent that statements contained in this press release are not descriptions of historical facts regarding Ardelyx, they are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor of the Private Securities Litigation Reform Act of 1995, including Ardelyx’s current expectations regarding the anticipated presentations at the American College of Gastroenterology (ACG) 2026 Annual Scientific Meeting, including the timing and content of the poster presentations and the Product Theater session, and continued research into the potential role of tenapanor in CIC. Such forward-looking statements involve known and unknown risks, uncertainties and other factors that are, in some cases, beyond our control and that could cause actual outcomes or results to differ materially from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, uncertainties associated with the development of, regulatory process for, and commercialization of drugs in the U.S. and internationally, and the risk that real-world, observational, survey or other analyses may not be indicative of future results or may be interpreted differently by others. Ardelyx undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to Ardelyx’s business in general, please refer to Ardelyx’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on August 6, 2026, and its future current and periodic reports to be filed with the Securities and Exchange Commission.

Investor Contact:
Lisa Caperelli
SVP, Investor Relations & Corporate Communications
lcaperelli@ardelyx.com

Media Contact:
Lindsey Manuel
Associate Director, Corporate Communications
lmanuel@ardelyx.com

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