Ardenwood Blvd Fremont, CA 94555 (510) 745-1700 Tele (510) 745-0493 Fax www.ardelyx.com Ardelyx Reports First Quarter 2016 Financial Results Conference Call and Webcast Today at 4:30 p.m.

Ardelyx Reports First Quarter 2016 Financial Results

Conference Call and Webcast Today at 4:30 p.m. ET

FREMONT, Calif., May 9, 2016 /PRNewswire/ Ardelyx, Inc. (NASDAQ: ARDX), a clinical-stage biopharmaceutical company focused on

gastrointestinal and cardio-renal diseases, today announced financial results for the first quarter ended March 31, 2016.

with the progress we have made thus far in 2016, said Mike Raab, President and Chief Executive Officer of Ardelyx. The remainder of the year looks to be an exciting period for Ardelyx, as we expect to execute on multiple upcoming

milestones. We expect results from the second Phase 2b clinical trial evaluating tenapanor for the treatment of hyperphosphatemia in ESRD patients in the second half of 2016. We look forward to building upon the positive results from our clinical

trial evaluating the pharmacodynamic activity of the lead product candidate from our RDX022 program in healthy volunteers, which we announced in January, and we plan to initiate a Phase 3 clinical trial in patients with hyperkalemia during the

fourth quarter 2016. In the fourth quarter, we also expect to submit an IND for RDX98940, the lead development candidate from our RDX009 program.

Highlights from the First Quarter 2016 and Upcoming Clinical Milestones

First Quarter Ended March 31, 2016 Financial Results

Net loss for the first quarter of 2016 was $23.5 million, or $0.70 per basic and diluted share, compared to a net loss of $3.5 million, or $0.19 per basic and

diluted share for the first quarter of 2015.

Total revenue is comprised of licensing revenue and collaborative development revenue. Licensing revenue for the

first quarter of 2016 decreased to zero from $3.9 million for the first quarter of 2015. Licensing revenue for the three months ended March 31, 2015 related to the recognition of revenue from upfront and milestone payments received from

AstraZeneca. As our collaboration agreement with AstraZeneca was terminated in June 2015, there was no further recognition of revenue related to the upfront and milestone payments after the six-month period ended June 30, 2015.

Collaborative development revenue is comprised of development expenses that were reimbursable to Ardelyx by AstraZeneca. Collaborative development revenue for

the first quarter of 2016 decreased to zero from $2.0 million for the first quarter of 2015. The decrease was attributable to the termination of the AstraZeneca agreement in June 2015 and related cessation of reimbursement of research and

development expenses.

Research and development expense for the first quarter of 2016 increased to $19.3 million from $6.2 million for the first quarter

of 2015. The increase was due to expenses incurred primarily for clinical development activities as well as clinical manufacturing and process development activities associated with tenapanor and RDX227675.

General and administrative expense was $4.3 million for the first quarter of 2016 as compared to $3.2 million for first quarter of 2015. The increase was

primarily due to an increase in professional services fees, personnel and public company costs.

Cash and cash equivalents were $171.7 million as of

March 31, 2016 compared with $107.0 million as of December 31, 2015 primarily because of an underwritten public offering completed in January 2016 that yielded approximately $80.8 million in net proceeds, offset by $16.1 million in cash

required for operating and other activities.

Conference Call & Webcast Information

Ardelyx management will host a live conference call and webcast today at 4:30 p.m. ET to discuss the financial results for the first quarter ended

March 31, 2016. The live webcast and a replay may be accessed by visiting the investor relations section of the Ardelyx website at ir.ardelyx.com.

Please connect to the Company s website at least 15 minutes prior to the live webcast to ensure adequate time for any software download that may be

needed to access the webcast. Alternatively, please call 1-855-296-9612 (US) or 920-663-6277 (International) to listen to the live conference call. The conference ID number for the live call is 1292888. Please dial in approximately 10 minutes prior

to the call. An archived webcast replay will be available on the Company s website until May 23, 2016.

Ardelyx is a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of innovative, minimally-systemic, small

molecule therapeutics that work exclusively in the gastrointestinal tract to treat gastrointestinal and cardio-renal diseases. Ardelyx has developed a proprietary drug discovery and design platform enabling it, in a rapid and cost-efficient manner,

to discover and design novel drug candidates. Utilizing this platform, Ardelyx has discovered and designed tenapanor, which it is evaluating for the treatment of constipation-

predominant irritable bowel syndrome, or IBS-C, and management of hyperphosphatemia in patients with end-stage renal disease. In addition to tenapanor, Ardelyx is developing RDX227675, a

non-absorbed polymer for the treatment of hyperkalemia, or high potassium, in kidney and heart disease patients. Ardelyx is also advancing several research programs focused in gastrointestinal and cardio-renal diseases. Ardelyx is located in

Fremont, California. For more information, please visit Ardelyx s website at www.ardelyx.com.

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 Reform Act of 1995, including the potential for tenapanor in treating IBS-C and hyperphosphatemia in end-stage renal disease

patients, Ardelyx s future development plans for tenapanor and the timing thereof, the expected timing for the receipt of results from T3MPO-1 and T3MPO-2, the two ongoing Phase 3 clinical trials evaluating tenapanor for the treatment of

IBS-C, the expected timing for the receipt of the results for the Phase 2b hyperphosphatemia clinical trial, the potential for RDX227675 in treating hyperkalemia in kidney and heart disease patients, Ardelyx s future development plans for

RDX227675 and the timing thereof, the expected timing for the initiation of the Phase 3 clinical trial for RDX227675, the expected timing for the filing of an IND for RDX98940, and the potential of Ardelyx s drug discovery and design platform.

Such forward-looking statements involve substantial risks and uncertainties that could cause the development of tenapanor, RDX227675, or Ardelyx s future results, performance or achievements to differ significantly from those expressed or

implied by the forward-looking statements. Such risks and uncertainties include, among others, the uncertainties inherent in research and the clinical development process and the uncertainties in the manufacture of clinical trial material, including

process development, scale up and tech transfer of manufacturing processes. 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 May 9, 2016, and its future current and periodic reports to be filed with the Securities and Exchange Commission.

Condensed Balance Sheets

Statements of Operations and Comprehensive Loss

(In thousands, except share and per share amounts)

Investor and Media Contact:

Chief Financial Officer

Burns McClellan on behalf of Ardelyx Inc.

SOURCE Ardelyx, Inc.