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RDX5791

Phase 4FDA approved

Constipation Predominant Irritable Bowel Syndrome | Small molecule | Gastrointestinal |Ardelyx, Inc.|Trials Updated: Sep 22, 2026

RDX5791 development status

FDA approval on record Approved
Highest phase Phase 4 (NCT05995899)
Phase scored for ARDXPhase 2
Registered trials 26 across 4 sponsors since Apr 2011

RDX5791 target and mechanism

ModalitySmall molecule

Also known as AZD1722, Tenapanor, AZD1722 (in-patient)

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLED
Total Trials17
Total Enrollment5,602

FDA Designations

No designations recorded

RDX5791 clinical trials

RDX5791 · 17 trials · 12 indications

Phase 3 8Phase 2 8Phase 1 1
NCT07382167A 26-Wk Study to Assess Safety & Efficacy of Tenapanor for T/t of Chronic Idiopathic Constipation in AdultsChronic Idiopathic Constipation (CIC)
RECRUITING692 Analytics
NCT05905926Safety Study of Tenapanor for the Treatment of Pediatric Patients (6 to Less Than 18 Years Old) With IBS-CIrritable Bowel Syndrome With Constipation (IBS-C)
ENROLLING BY_INVITATION150 Analytics
NCT05643534Study to Assess Safety and Efficacy of Tenapanor for Treatment of IBS-C in Pediatric Patients 12 to Less Than 18 YearsIrritable Bowel Syndrome With Constipation (IBS-C)
COMPLETED180 Analytics
NCT03427125A Phase 3 Study of Tenapanor to Treat Hyperphosphatemia in ESRD Patients on DialysisHyperphosphatemia
COMPLETED1,559 Analytics
NCT02727751A Long-Term Safety Study of Tenapanor for the Treatment of IBS-CConstipation Predominant Irritable Bowel Syndrome
COMPLETED312 Analytics
NCT02675998An 8-Week Study to Evaluate Tenapanor in the Treatment of Hyperphosphatemia in End-Stage Renal Disease Patients on Hemodialysis (ESRD-HD)Hyperphosphatemia
COMPLETED219 Analytics
NCT02686138A 26-Week Study to Evaluate the Efficacy and Safety of Tenapanor in IBS-CConstipation Predominant Irritable Bowel Syndrome
COMPLETED593 Analytics
NCT02621892A 12-Week Study With a 4-Week Randomized Withdrawal Period to Evaluate the Efficacy and Safety of Tenapanor for the Treatment of IBS-CConstipation Predominant Irritable Bowel Syndrome
COMPLETED606 Analytics
PHASE3RECRUITING
A 26-Wk Study to Assess Safety & Efficacy of Tenapanor for T/t of Chronic Idiopathic Constipation in Adults
Chronic Idiopathic Constipation (CIC)Unlock trial analytics
PHASE3ENROLLING BY_INVITATION
Safety Study of Tenapanor for the Treatment of Pediatric Patients (6 to Less Than 18 Years Old) With IBS-C
Irritable Bowel Syndrome With Constipation (IBS-C)Unlock trial analytics
PHASE3COMPLETED
Study to Assess Safety and Efficacy of Tenapanor for Treatment of IBS-C in Pediatric Patients 12 to Less Than 18 Years
Irritable Bowel Syndrome With Constipation (IBS-C)Unlock trial analytics
PHASE3COMPLETED
A Phase 3 Study of Tenapanor to Treat Hyperphosphatemia in ESRD Patients on Dialysis
HyperphosphatemiaUnlock trial analytics
PHASE3COMPLETED
A Long-Term Safety Study of Tenapanor for the Treatment of IBS-C
Constipation Predominant Irritable Bowel SyndromeUnlock trial analytics
PHASE3COMPLETED
An 8-Week Study to Evaluate Tenapanor in the Treatment of Hyperphosphatemia in End-Stage Renal Disease Patients on Hemodialysis (ESRD-HD)
HyperphosphatemiaUnlock trial analytics
PHASE3COMPLETED
A 26-Week Study to Evaluate the Efficacy and Safety of Tenapanor in IBS-C
Constipation Predominant Irritable Bowel SyndromeUnlock trial analytics
PHASE3COMPLETED
A 12-Week Study With a 4-Week Randomized Withdrawal Period to Evaluate the Efficacy and Safety of Tenapanor for the Treatment of IBS-C
Constipation Predominant Irritable Bowel SyndromeUnlock trial analytics

Study Endpoints

Primary Endpoints

Durable complete spontaneous bowel movements (CSBM) response
12 Weeks

Durable complete spontaneous bowel movements (CSBM) response is defined as achieving the weekly CSBM response for ≥9 out of the first 12 weeks of the randomized treatment period and and for ≥3 of the last 4 weeks of the first 12 weeks of randomized treatment period

Safety Measure Assessment (Adverse Event)
40 weeks

Incidence of AEs, SAEs and drug related adverse events

Safety Measure Assessment (ECG)
40 weeks

Descriptive summaries of ECG parameters (heart rate, PR-interval, QRS-duration, QT-interval, QTc-interval, and RR-interval)

6/12-week APS (abdominal pain and SBM) +2 response
12 weeks

6/12-week APS (abdominal pain and SBM (spontaneous bowel movement)) +2 response, defined as achieving the weekly APS +2 response criteria (i.e., achieving both weekly SBM +2 response and weekly abdominal pain response during the same week) for ≥6 out of the 12 weeks of the RTP. * The weekly SBM +2 response is defined as having an increase of ≥2 from baseline in the average weekly SBM frequency for a given week * The weekly abdominal pain response is defined as having ≥30% reduction from baseline in the average weekly abdominal pain score for a given week

Change in Serum Phosphorus Levels During Placebo Controlled Randomized Withdrawal Period in the Responder Population
12 weeks (randomized withdrawal period)

Patients with at least a 1.2 mg/dL decrease in serum phosphorus during the first 26 weeks of the study were defined as the responder population.

Adverse Events in >2% Patients
52-55 weeks

Safety assessments will be based on adverse events, clinical laboratory tests, vital signs, ECG, and physical exams

Placebo Adjusted Change in Serum Phosphate During Randomized Withdrawal Period From Pooled Tenapanor Arms
4 weeks

Serum phosphorus difference between placebo and tenapanor in the change from the end of the 8 week treatment period to the end of the randomized withdrawal period in Efficacy Analysis Set. The efficacy analysis was pre-defined to be a pooled analysis of all tenapanor treated patients with a minimum of a 1.2 mg/dL decrease in serum phosphorus during the 8-week treatment period

Percentage of Subjects With Overall Response for 6 Out of 12 Weeks
First 12 weeks

An overall responder is defined as a weekly responder for the first 6/12 weeks where both CSBM and abdominal pain response criteria were met for the week. The CSBM response criteria are defined as an increase of one or more change in average weekly CSBMs from baseline. The definition of a CSBM is as follows: A CSBM is a spontaneous bowel movement (SBM) for which the subject responds "yes" to the following question; "Did you feel like you completely emptied your bowels?" The abdominal pain response criterion is defined as a decrease of 30% or more of percent change in average weekly worst abdominal pain from baseline.

6 of 12 Week Overall Responder Rate
12 weeks

An overall responder is defined as a weekly responder for the first 6/12 weeks where both CSBM and abdominal pain response criteria were met for the week. The CSBM response criteria are defined as an increase of one or more change in average weekly CSBMs from baseline. The definition of a CSBM is as follows: A CSBM is a spontaneous bowel movement (SBM) for which the subject responds "yes" to the following question; "Did you feel like you completely emptied your bowels?" The abdominal pain response criterion is defined as a decrease of 30% or more of percent change in average weekly worst abdominal pain from baseline.

Complete spontaneous bowel movements (CSBM)
6 of 12 weeks

Our primary endpoint will be CSBM response, defined as an increase of at least one CSBM per week compared to baseline for at least 6 of the 12 treatment weeks. A CSBM is defined as a bowel movement that occurs naturally and is accompanied by a feeling of complete evacuation

Average weekly SBM (week 4)
4 weeks

Change from baseline in average weekly SBM frequency in Week 4

Change in Serum Phosphorus (s-P) Level From Baseline to Week 4.
4 Weeks (28 days randomization period; from baseline to week 4)

Difference in mean change from baseline in s-P level at Week 4 between the tenapanor and placebo groups.

Change in Serum Phosphate Levels
End of wash out (pre randomization value) to end of treatment (Day 29)

Change in serum phosphate levels from the end of wash out (pre randomization value) to end of treatment

Percent Complete Spontaneous Bowel Movement Responders vs Placebo
12 weeks

Weekly complete spontaneous bowel movement resaponders defined as an increase of one or more bowel movement per week from baseline for 6 of the 12 weeks

Changes in Urine Albumin to Creatinine Ratio (UACR)
Week 12

The difference between tenapanor and placebo in the change in UACR from baseline to the end of 12 weeks of treatment

Change in Mean Weekly Interdialytic Weight Gain (IDWG)
Run-in period (Weeks -2 and -1) versus Week 4 (end of treatment)

Patients are weighed pre dialysis prior to their first dialysis of the week. This measure looks at the change in pre-dialysis weight over time

Complete Spontaneous Bowel Movement (CSBM) Frequency Change From Baseline
Baseline and Week 4

Patients complete a phone diary daily. They are asked "how many bowel movements have you had today?" they are then asked for each spontaneous bowel movement (unaided with laxative use) wether there was its was a complete evacuation. if it was then it is a complete spontaneous bowel movement. All CSBMs are added and adjusted for a mean compete sponteneous bowel movement.

Concentration of tenapanor and its major metabolite in breast milk
26 Days

The primary objective of the study is to determine the maximum observed milk concentration (Cmax) of tenapanor and its primary metabolite AZ13792925 in the breast milk of lactating female subjects.

Secondary Endpoints

9/12 week complete spontaneous bowel movements (CSBM) response
12 Weeks
Change from baseline in complete spontaneous bowel movements (CSBM) frequency
12 Weeks
Change from baseline in spontaneous bowel movement (SBM) frequency
12 Weeks
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Tenapanor 5 mg BIDEXPERIMENTALPatients will be randomized to receive 5 mg tenapanor twice daily.
Tenapanor 25 mg BIDEXPERIMENTALPatients will be randomized to receive 25 mg tenapanor twice daily.
Tenapanor 50 mg BIDEXPERIMENTALPatients will be randomized to receive 50 mg tenapanor twice daily.
Placebo ComparatorPLACEBO_COMPARATORPatients will be randomized to receive matching placebo twice daily.
TenapanorEXPERIMENTALEligible patients from the parent study will continue tenapanor at the same dose assigned in the parent study which can be titrated to either 50 mg BID or 25 mg BID per Investigator guidance after a patient's first week on the assigned dose.
Tenpanor 50 mg BIDEXPERIMENTALPatients will be randomized to receive 50 mg tenapanor twice daily
Tenpanor 25 mg BIDEXPERIMENTALPatients will be randomized to receive 25 mg tenapanor twice daily
Tenapanor 10 mg, 20 mg, 30 mg BIDEXPERIMENTALDuring the 26-week open label part, all enrolled subjects will receive 30 mg BID doses of tenapanor. Investigators may decrease or increase the dose in 10 mg increments to a minimum of 10 g BIDor a maximum of 30 mg BID
PlaceboPLACEBO_COMPARATORPlacebo
Sevelamer CarbonateACTIVE_COMPARATORSubjects randomized into the active control group, for safety analysis, will receive sevelamer carbonate, open label, for the entire 52-week study period. Sevelamer carbonate will be dosed based on package insert instructions (standard of care)
50mg BIDEXPERIMENTALTenapanor, 50 mg BID (100 mg total)
3mg BIDEXPERIMENTALTenapanor, 3mg BID (6mg total)
10mg BIDEXPERIMENTALTenapanor, 10mg BID (20mg total)
Dose TitrationEXPERIMENTALTenapanor, patients start at 30mg BID and can down titrate weekly to 20, 15, 10, and 3mg BID, sequentially based on a GI tolerability question
Tenapanor Cohort 1EXPERIMENTALTenapanor 2 mg BID
Tenapanor Cohort 2EXPERIMENTALTenapanor 5 mg BID
Tenapanor Cohort 3EXPERIMENTALTenapanor 10 mg BID
Tenapanor Cohort 4EXPERIMENTALTenapanor 15 mg BID
Tenapanor Cohort 5EXPERIMENTALTenapanor 20 mg BID
Tenapanor Cohort 6EXPERIMENTALTenapanor 25 mg BID
Tenapanor 30 mg BIDEXPERIMENTALDuring the Double-Blind Treatment Period, subjects will receive tenapanor starting at a dose of 30 mg bid (three 10 mg tablets each time). Investigators may decrease or increase the dose of study medication based on s-P levels and/or gastrointestinal (GI) tolerability in 10 mg increments to a minimum of 10 mg bid or a maximum of 30 mg bid at any time during the Double-Blind Treatment Period.
1 mg bidEXPERIMENTAL1 mg AZD1722 bid
3 mg bidEXPERIMENTAL3 mg AZD1722 bid
10 mg bidEXPERIMENTAL10 mg AZD1722 bid
30 mg bidEXPERIMENTAL30 mg AZD1722 bid
3 mg odEXPERIMENTAL3 mg AZD1722 od
30 mg odEXPERIMENTAL30 mg AZD1722 od
5 mg BIDEXPERIMENTALAZD1722
20 mg BIDEXPERIMENTALAZD1722
50 mg BIDEXPERIMENTALAZD1722
AZD1722ACTIVE_COMPARATORAZD1722 in 5, 15, 30, or 60 mg capsules. Starting dose is 15 mg BID PO for 12 Weeks
AZD1722- in patientEXPERIMENTALTenapanor administered in a clinical pharmacology unit
Placebo- in patientPLACEBO_COMPARATORPlacebo (size and color matched to experimental drug) administered in a clinical pharmacology unit
AZD1722 out-patientEXPERIMENTALTenapanor
Placebo out-patientEXPERIMENTALPlacebo
Low DoseEXPERIMENTAL10 mg capsule of tenapanor
Mid DoseEXPERIMENTAL30 mg capsule of tenapanor
High DoseEXPERIMENTAL100 mg capsule of tenapanor
Treatment ArmEXPERIMENTALEligible subjects will be enrolled to receive the study drug

Interventions

NameTypeDescription
Tenapanor 5 mg BIDDRUGPatients will receive tenapanor 5 mg BID (total of 10 mg daily)
Tenapanor 25 mg BIDDRUGPatients will receive tenapanor 25 mg BID (total of 50 mg daily)
Tenapanor 50 mg BIDDRUGPatients will receive tenapanor 50 mg BID (total of 100 mg daily)
PlaceboDRUGPatients will receive matching placebo BID
TenapanorDRUGEligible patients from the parent study will continue tenapanor at the same dose assigned in the parent study. Doses can be titrated to either 50 mg BID or 25 mg BID
Tenapanor 50 MGDRUGParticipants will receive tenapanor 50 mg BID (total of 100 mg daily)
Sevelamer CarbonateDRUGActive control
Phosphate Binder AgentsDRUGstandard of care phosphate binder use at study entry was maintained throughout the entire study
AZD1722DRUGAZD1722, oral tablet
AZD1722 (in-patient)DRUGdoses between 5 and 60 mg BID may be administered based on tolerability in a CPU setting
Placebo (in-patient)DRUGPlacebo, size and color matched to experimental drug administered in a CPU
AZD1722 (out-patient)DRUGdoses between 5 and 45 mg BID
RDX5791DRUGCapsule, QD
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Eligibility Criteria

Age Range18 Years to 80 Years
SexALL
Healthy VolunteersNo
Study Sites109

Inclusion Criteria: 1. Patients ≥18 to ≤80 years old at the Screening visit (Visit 1). 2. Meet the Rome IV Diagnostic Criteria for functional constipation. 3. Females of non-childbearing potential, or agree to the use of an acceptable means of contraception for up to 30 days following the last dose...

Countries:United StatesPolandSlovakiaUnited Kingdom
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Recent Changes (Last 90 Days)

HIGHSep 22, 2026NCT05643534Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHSep 22, 2026NCT05643534Status: ACTIVE_NOT_RECRUITING → COMPLETED
MEDIUMSep 19, 2026NCT06553547TRIAL_REMOVED: changed
MEDIUMSep 19, 2026NCT06553547TRIAL_REMOVED: changed
MEDIUMSep 19, 2026NCT06553547TRIAL_REMOVED: changed
HIGHAug 20, 2026NCT06553547Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHAug 20, 2026NCT06553547Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHAug 20, 2026NCT06553547Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHAug 20, 2026NCT06553547Status: ACTIVE_NOT_RECRUITING → COMPLETED

Frequently asked questions about RDX5791

What is RDX5791?

RDX5791 is an investigational small molecule developed by Ardelyx, Inc. for the treatment of constipation predominant irritable bowel syndrome, commonly called IBS-C. It has been studied in a Phase 2 clinical trial. RDX5791 is not approved and remains in clinical development.

What is RDX5791 used for in Constipation Predominant Irritable Bowel Syndrome?

RDX5791 was studied as a treatment for constipation predominant irritable bowel syndrome, or IBS-C, a gastrointestinal condition. The Phase 2 trial enrolled adults 18 years and older with IBS-C in the United States. RDX5791 is investigational and has not been approved for this or any other use.

Who makes RDX5791?

RDX5791 is developed by Ardelyx, Inc., a biopharmaceutical company that trades under the ticker ARDX. Ardelyx sponsored the Phase 2 study of RDX5791 in constipation predominant irritable bowel syndrome. No other developer or partnership for RDX5791 has been announced.

What phase is RDX5791 in?

RDX5791 is in Phase 2 development. One Phase 2 trial has been completed, and no trials are currently active. The study evaluated RDX5791 for constipation predominant irritable bowel syndrome. RDX5791 is investigational and has not received FDA approval.

What clinical trials is RDX5791 in?

RDX5791 has been studied in one completed Phase 2 trial, NCT01340053, titled a study to evaluate the safety and efficacy of RDX5791 for the treatment of constipation predominant irritable bowel syndrome. The trial enrolled 186 participants in the United States and was randomized, double blind, and placebo controlled.

How was the RDX5791 Phase 2 trial designed?

The Phase 2 trial of RDX5791, NCT01340053, was a randomized, double blind, placebo controlled study in adults with constipation predominant irritable bowel syndrome. It enrolled 186 participants aged 18 years and older in the United States and has been completed. No biomarker selection was used in the study.