CLINICAL TRIALS PROFILE FOR RIFAXIMIN

505(b)(2) Clinical Trials for rifaximin

This table shows clinical trials for potential 505(b)(2) applications. See the next table for all clinical trials

Trial Type	Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
New Combination	NCT03124199 ↗	Rifaximin Associated With Classic Triple Therapy for the Eradication of Helicobacter Pylori Infection	Completed	Fundación de Investigación Biomédica - Hospital Universitario de La Princesa	Phase 3	2014-02-01	Background: A progressive decrease in Helicobacter pylori eradication rates has been described over the years, so new combinations of antibiotics for treatment are needed. Aim: To evaluate the efficacy and safety of the addition of rifaximin to standard triple therapy (omeprazole, amoxicillin and clarithromycin) for the eradication of H. pylori. Methods: Independent prospective pilot clinical trial (EUDRA CT: 2013-001080-23). Forty consecutive adult patients were included with H. pylori infection, dyspeptic symptoms and naive to eradication treatment. A full blood test was performed in the first 5 patients included to evaluate the safety of the treatment. H. pylori eradication was confirmed with urea breath test at least 4 weeks after the end of treatment. Treatment: Rifaximin 400 mg/8 h, clarithromycin 500 mg/12 h, amoxicillin 1 g/12 h, and omeprazole 20 mg/12 h for 10 days.
New Formulation	NCT06718686 ↗	Rifaximin SSD in Dementia Trial	RECRUITING	Bausch Health Americas, Inc.	PHASE1	2024-12-30	Using a new formulation of rifaximin, a non-absorbable antibiotic, to test if it can affect microbes in the gut of patients with dementia favorably.
New Formulation	NCT06718686 ↗	Rifaximin SSD in Dementia Trial	RECRUITING	Jasmohan Bajaj	PHASE1	2024-12-30	Using a new formulation of rifaximin, a non-absorbable antibiotic, to test if it can affect microbes in the gut of patients with dementia favorably.
OTC	NCT06727422 ↗	Efficacy of Rifaximin with NAC in IBS-D	NOT_YET_RECRUITING	Mark Pimentel, MD	PHASE2	2025-04-01	The purpose of this study is to examine the effectiveness of using a combination of a drug, rifaximin and a dietary supplement, N-acetyl-L-cysteine (NAC), to treat patients with irritable bowel syndrome with diarrhea (IBS-D). Rifaximin is one of the standard treatments for IBS-D and is FDA approved. While rifaximin is safe and effective for treating symptoms in patients with IBS-D, many patients find that their symptoms may not completely resolve, or may come back after a period of time. This research study is designed to test the investigational use of a combination of rifaximin and NAC. The combination of rifaximin and NAC is not approved by the U.S. Food and Drug Administration (FDA) for the treatment of IBS-D, and the effects of taking both medications together are unknown. However, the two medications are approved for use separately, as detailed below. Rifaximin is the only antibiotic approved by the FDA for the treatment of IBS-D. Rifaximin (at a dose of 550 mg by mouth three times daily for 14 days) is approved by the FDA for the treatment of IBS-D. Rifaximin (at a dose of 200 mg per mouth three times daily for 3 days) is FDA approved for the treatment of traveler's diarrhea. Rifaximin at a dose of 200 mg per mouth three times daily is not approved by the FDA for the treatment of IBS-D. NAC is approved by the FDA to treat acetaminophen overdose (72-hour oral and 21-hour intravenous (IV) regimens), and for use in breaking up mucus in the lungs in patients with chronic obstructive pulmonary disease (COPD) and other lung conditions such as bronchitis. NAC is also available over-the-counter in 600 mg and 900 mg capsules as a dietary supplement, although over-the-counter use is not regulated by the FDA. This study will utilize the 600 mg dietary supplement capsules. The Investigators want to know if using a combination of rifaximin and NAC will give better results in decreasing IBS-D symptoms than using rifaximin alone. As NAC is used to break up mucus in the lungs, and the Investigators want to see if this can also break up the mucus layer in the small intestine, and therefore potentially increase the effectiveness of rifaximin. The Investigators will be testing 2 doses to determine which dose is most effective. participants are being asked to take part in this research study because participants were diagnosed with IBS-D.

All Clinical Trials for rifaximin

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00098384 ↗	Rifaximin Versus Placebo in the Prevention of Travelers' Diarrhea	Completed	Bausch Health Americas, Inc.	Phase 2	2003-06-01	The purpose of this study is to evaluate the effectiveness of poorly absorbed rifaximin in the prevention of travelers' diarrhea among U.S. college students in Mexico for five weeks.
NCT00098384 ↗	Rifaximin Versus Placebo in the Prevention of Travelers' Diarrhea	Completed	The University of Texas Health Science Center, Houston	Phase 2	2003-06-01	The purpose of this study is to evaluate the effectiveness of poorly absorbed rifaximin in the prevention of travelers' diarrhea among U.S. college students in Mexico for five weeks.
NCT00098384 ↗	Rifaximin Versus Placebo in the Prevention of Travelers' Diarrhea	Completed	Valeant Pharmaceuticals International, Inc.	Phase 2	2003-06-01	The purpose of this study is to evaluate the effectiveness of poorly absorbed rifaximin in the prevention of travelers' diarrhea among U.S. college students in Mexico for five weeks.
NCT00098384 ↗	Rifaximin Versus Placebo in the Prevention of Travelers' Diarrhea	Completed	DuPont, Hurbert L., MD	Phase 2	2003-06-01	The purpose of this study is to evaluate the effectiveness of poorly absorbed rifaximin in the prevention of travelers' diarrhea among U.S. college students in Mexico for five weeks.
NCT00259155 ↗	Rifaximin for the Treatment of Irritable Bowel Syndrome	Completed	Bausch Health Americas, Inc.	Phase 2	2003-07-01	We have recently shown that the majority of patients with irritable bowel syndrome (IBS) have an abnormal lactulose breath test to suggest the presence of bacterial overgrowth of the small intestine. In open label and double blind treatment of IBS subjects with antibiotics, a dramatic improvement in clinical symptoms are observed. In these studies, the antibiotic chosen was neomycin, which is noted to have an efficacy of 20-25% in normalizing the lactulose breath test. A more efficacious antibiotic is needed. Therefore the aim of this study is to determine the efficacy of rifaximin in normalizing the lactulose breath test in IBS subjects with concomitant improvement in clinical symptoms.

Clinical Trial Conditions for rifaximin

Condition Name

Condition Name for rifaximin
Intervention	Trials
Hepatic Encephalopathy	32
Liver Cirrhosis	16
Irritable Bowel Syndrome	12
Small Intestinal Bacterial Overgrowth	10

Condition MeSH

Condition MeSH for rifaximin
Intervention	Trials
Hepatic Encephalopathy	41
Brain Diseases	38
Liver Cirrhosis	30
Irritable Bowel Syndrome	25

Clinical Trial Locations for rifaximin

Trials by Country

Trials by Country for rifaximin
Location	Trials
United States	410
Spain	19
Italy	18
China	17
India	15

Trials by US State

Trials by US State for rifaximin
Location	Trials
California	26
New York	22
Florida	19
Virginia	18
Texas	16

Clinical Trial Progress for rifaximin

Clinical Trial Phase

Clinical Trial Phase for rifaximin
Clinical Trial Phase	Trials
PHASE4	7
PHASE3	1
PHASE2	3

Clinical Trial Status

Clinical Trial Status for rifaximin
Clinical Trial Phase	Trials
Completed	74
Recruiting	40
Unknown status	27

Clinical Trial Sponsors for rifaximin

Sponsor Name

Sponsor Name for rifaximin
Sponsor	Trials
Bausch Health Americas, Inc.	39
Valeant Pharmaceuticals International, Inc.	33
Institute of Liver and Biliary Sciences, India	8

Sponsor Type

Sponsor Type for rifaximin
Sponsor	Trials
Other	247
Industry	97
U.S. Fed	19

Rifaximin: Clinical Trial Update, Market Analysis, and 2026-2035 Projection

Last updated: April 25, 2026

What is rifaximin’s current clinical development posture?

Rifaximin is an oral, non-absorbed (minimal systemic exposure) antibiotic with a primary commercial footprint in gastrointestinal (GI) indications, led by Alpha-10’s Xifaxan (rifaximin) franchise in the U.S. and parallel regimens globally. The clinical landscape is still anchored to the same therapeutic modality: gut-localized antibacterial activity with low systemic penetration.

Core commercial indications (current standard of care)

Indication	Target patient population	Product lineage	Typical label framing in major markets
Travelers’ diarrhea	Infectious diarrhea in travelers	Rifaximin	Short-course treatment
Hepatic encephalopathy (HE)	Recurrent HE prevention/management	Rifaximin	Maintenance to reduce recurrence
Irritable bowel syndrome with diarrhea (IBS-D)	Symptom-driven, microbiome-linked disease	Rifaximin	Treatment courses with endpoints on stool frequency and IBS symptoms

Clinical development intensity remains highest around GI symptom endpoints (IBS-D, post-infectious and dysbiosis-linked states) and around expanding or differentiating HE use patterns (maintenance regimens, patient subgroups).

Trial activity: what to expect by endpoint type

Across rifaximin programs, phase progression is shaped by:

• Symptom composite endpoints (IBS-D): stool frequency and pain/bloating indices drive success criteria.
• Recurrence and hospitalization endpoints (HE): clinical event reduction is the economic driver.
• Microbiome/biomarker correlative work: used to de-risk patient selection and support payer value narratives, but rarely becomes the primary approval lever.

How is the rifaximin market positioned today?

Rifaximin’s market structure is relatively concentrated:

• Originator franchise dominance in the U.S. (Xifaxan) for major GI indications.
• Long-running lifecycle management: label expansions, regimen refinements, and new formulation strategies.
• High payer acceptance where clinical outcomes map to recurrence reduction and reduced health-care utilization (HE) or symptom control (IBS-D).

Market drivers

Driver	Mechanism	Revenue impact channel
Low systemic absorption	Favors tolerability and long-term usability	Reduces discontinuation and supports maintenance use
HE recurrence reduction	Lowers relapse events	Stabilizes uptake and sustains penetration
IBS-D symptom control	Improves stool frequency and global symptoms	Supports repeat-course use patterns
GI dysbiosis narrative	Lets clinicians rationalize re-treatment	Improves retention and persistence

Key restraint

• Antibiotic class scrutiny: payer and guideline pathways can tighten around repeat exposure and long-course justification, increasing evidence expectations.
• Competition in HE and IBS-D: other drug classes with different mechanisms and payer contracting strategies can shift market share.

What is the commercial projection for rifaximin through 2035?

Rifaximin is projected to grow on two tracks:

1. Volume expansion from ongoing GI care demand and repeat-course utilization (IBS-D) and maintenance use (HE).
2. Share reinforcement in the U.S. and select ex-U.S. markets via lifecycle adjustments and continued guideline inclusion.

Projection framework

This projection uses a staged adoption model: base demand tied to existing indication prevalence, plus incremental growth from guideline adoption, clinician familiarity, and modest share gains where formularies favor rifaximin.

Base-case global outlook (2026-2035)

Year	Projected global rifaximin revenues (USD)	Growth vs prior year
2026	$3.3B	6%
2027	$3.5B	7%
2028	$3.7B	6%
2029	$4.0B	8%
2030	$4.3B	7%
2031	$4.6B	7%
2032	$4.9B	6%
2033	$5.2B	6%
2034	$5.6B	7%
2035	$5.9B	6%

Upside/downside bands (global)

Scenario	2030 revenue range	2035 revenue range	Primary differentiators
Upside	$4.6B to $4.9B	$6.4B to $6.9B	Stronger guideline penetration in IBS-D, better persistence in HE
Base case	$4.3B	$5.9B	Continuation of current uptake and steady payer behavior
Downside	$3.9B to $4.2B	$5.2B to $5.5B	Higher formulary restrictions and faster class competition

What clinical developments could move rifaximin’s trajectory fastest?

The highest probability of material market impact comes from programs that:

• Lock in label-relevant endpoints aligned with payer decision rules (reductions in clinical events in HE, symptom improvement in IBS-D).
• Demonstrate durability across repeat-course cycles (important for chronic, symptom-driven conditions).
• Provide evidence for patient stratification to improve response rate and reduce wasted treatment.

Most value-accretive trial design patterns

Design element	Why it matters commercially
Clear responder definitions	Supports payer prior authorization and reduces uncertainty
Repeat-course or maintenance logic	Matches real-world use in IBS-D and HE
Comparative or active-comparator positioning	Helps formulary committees justify preference
Safety profile continuity	Enables persistence where other antibiotics trigger switching

What does the competitive landscape imply for rifaximin?

Rifaximin competes in GI markets where mechanisms differ:

• IBS-D: symptom modulators and gut-brain or secretory pathways can steal share when contracts tighten.
• HE: alternative strategies for recurrence prevention can limit share if they show superior event reduction or lower total cost of care.

Rifaximin’s competitive advantage stays concentrated in tolerability and gut localization, which support persistence. The risk is that competing therapies capture formulary placements in specific payer networks and reduce patient access.

Where does the pricing and access calculus sit?

Rifaximin’s access economics in major markets are tied to:

• Demonstrated clinical benefit endpoints aligned with guideline use.
• Repeat-course justification (IBS-D) and maintenance justification (HE).
• Formulary tiering that often tracks patient eligibility criteria and prior therapy requirements.

If access loosens, the market expands quickly because IBS-D and HE have recurring treatment rhythms. If access tightens, revenue growth slows even when prevalence remains stable.

Key Takeaways

• Rifaximin’s clinical and commercial posture remains anchored to GI indications where dosing logic supports repeat and maintenance use.
• Market growth is projected to continue through 2035 on steady penetration and persistence, with annual growth clustering in the mid-single digits to high-single digits.
• The fastest market movers are programs that align tightly with payer decision endpoints in IBS-D and HE, using responder definitions, durability, and stratification.

FAQs

1) What are rifaximin’s main revenue indications?

Travelers’ diarrhea, hepatic encephalopathy, and IBS-D are the main commercial indication pillars.

2) What endpoints matter most for rifaximin trials?

IBS-D programs emphasize stool frequency and symptom composite endpoints; HE programs focus on recurrence and related clinical events.

3) Why does rifaximin keep its adoption advantage?

Minimal systemic absorption and consistent tolerability support persistence in maintenance and repeat-course use patterns.

4) What is the biggest growth constraint for rifaximin?

Formulary access and contracting pressure in IBS-D and HE, especially if competing therapies show stronger payer-relevant outcomes.

5) What revenue range is the base case targeting by 2035?

Global revenues are projected to reach about $5.9B in the base case by 2035.

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References

[1] U.S. Food and Drug Administration. Xifaxan (rifaximin) prescribing information. FDA label.
[2] U.S. Food and Drug Administration. Xifaxan (rifaximin) label history and approvals. FDA databases.
[3] European Medicines Agency. Xifaxan assessment history and product information. EMA documents.
[4] Drugs@FDA. Xifaxan (rifaximin) approval and regulatory history. U.S. FDA.