CLINICAL TRIALS PROFILE FOR HYDROCHLOROTHIAZIDE; TRIAMTERENE

All Clinical Trials for hydrochlorothiazide; triamterene

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00000525 ↗	Diuretics, Hypertension, and Arrhythmias Clinical Trial	Completed	National Heart, Lung, and Blood Institute (NHLBI)	Phase 3	1986-07-01	To determine whether hypertensive patients with ECG abnormalities and receiving hydrochlorothiazide diuretics were at increased risk of sudden death.
NCT00000525 ↗	Diuretics, Hypertension, and Arrhythmias Clinical Trial	Completed	University of California, San Francisco	Phase 3	1986-07-01	To determine whether hypertensive patients with ECG abnormalities and receiving hydrochlorothiazide diuretics were at increased risk of sudden death.
NCT00007592 ↗	Hypertension Screening and Treatment Program	Completed	US Department of Veterans Affairs		1989-06-01	Hypertension is one of the most common medical problems in the United States and in the VA health care system. It has been well-documented that hypertension can be effectively treated. However, there remain important unresolved clinical questions in the area of antihypertensive treatment. For example, how much is mortality affected by visit compliance, blood pressure control and type of antihypertensive agent? Or, are some regimens associated with more morbidity than others? Or, are there inexpensive regimens that are as effective as more expensive regimens? The amount of data that is available from this demonstration project (currently 6,100 patients) will help address these questions. The answers to these questions should result in better care for veterans with hypertension.
NCT00007592 ↗	Hypertension Screening and Treatment Program	Completed	VA Office of Research and Development		1989-06-01	Hypertension is one of the most common medical problems in the United States and in the VA health care system. It has been well-documented that hypertension can be effectively treated. However, there remain important unresolved clinical questions in the area of antihypertensive treatment. For example, how much is mortality affected by visit compliance, blood pressure control and type of antihypertensive agent? Or, are some regimens associated with more morbidity than others? Or, are there inexpensive regimens that are as effective as more expensive regimens? The amount of data that is available from this demonstration project (currently 6,100 patients) will help address these questions. The answers to these questions should result in better care for veterans with hypertension.
NCT01661777 ↗	Refractory Eustachian Tube Dysfunction: Are the Symptoms Related to Endolymphatic Hydrops	Withdrawn	Vanderbilt University	N/A	2012-08-01	The purpose of this study is to evaluate the benefit of treatment of refractory Eustachian tube dysfunction with standard treatment for endolymphatic hydrops. Eustachian tube dysfunction is a common diagnosis made in otolaryngology related to abnormal pressure equalization of the middle ear space related to a swollen, inflamed, or occluded Eustachian tube. The symptoms of this include perceived hearing loss, a feeling of fullness in the affected ear/ears, ear pain, ear popping, and occasionally imbalance. These symptoms overlap with a more rare and difficult to diagnose condition known as endolymphatic hydrops, or an overproduction to fluid in the inner ear. The treatment for these two conditions are distinct and traditionally, patients are treated for Eustachian tube dysfunction first as it is much more common and there are several treatments, namely nasal steroids, antihistamines, and pressure equalization tubes. For patients who do not improve with these treatments, they are often treated with diuretics and a low salt diet to treat for supposed endolymphatic hydrops. There has never been a study to investigate the utility of these treatments in patients with refractory Eustachian tube dysfunction. There is also reason to believe that chronic ETD with effusion can lead to both inner and middle ear dysfunction. Thus, this study aims to determine the benefit of standard endolymphatic hydrops treatment on patient with refractory Eustachian tube dysfunction symptoms in a prospective fashion. Hypothesis: Patients with refractory Eustachian tube dysfunction (patients with no or minimal symptom improvement despite nasal steroid and antihistamine treatment followed by myringotomy tube placement) have an element of endolymphatic hydrops and these patient's symptoms will improve with a low sodium diet and diuretic.
NCT02217852 ↗	Treatment of Hypertension in Tibetan Adult Population	Unknown status	West China Hospital	Phase 4	2014-08-01	Several surveys had revealed that Tibetan adults had high prevalence of hypertension. However, there was no research studying the antihypertensive effect of the known drugs in Tibetan. The main arms of our study were to determine if the efficacy of lowing blood pressure and protecting target organ damage differs between nitrendipine and Hydrochlorothiazide in mild hypertension in Tibetan, and to determine if the efficacy of lowing blood pressure and protecting target organ damage differs between captopril plus Hydrochlorothiazide and Beijing hypotensive No.0 in moderate and severe Tibetan hypertension.

Clinical Trial Conditions for hydrochlorothiazide; triamterene

Condition Name

Condition Name for hydrochlorothiazide; triamterene
Intervention	Trials
Hypertension	3
Heart Arrest	1
Heart Diseases	1
Ménière	1

Condition MeSH

Condition MeSH for hydrochlorothiazide; triamterene
Intervention	Trials
Hypertension	3
Heart Arrest	1
Death, Sudden, Cardiac	1
Meniere Disease	1

Clinical Trial Locations for hydrochlorothiazide; triamterene

Trials by Country

Trials by Country for hydrochlorothiazide; triamterene
Location	Trials
United States	12
Puerto Rico	1
China	1

Trials by US State

Trials by US State for hydrochlorothiazide; triamterene
Location	Trials
Tennessee	2
California	2
Virginia	1
Pennsylvania	1
Ohio	1

Clinical Trial Progress for hydrochlorothiazide; triamterene

Clinical Trial Phase

Clinical Trial Phase for hydrochlorothiazide; triamterene
Clinical Trial Phase	Trials
Phase 4	2
Phase 3	1
N/A	1

Clinical Trial Status

Clinical Trial Status for hydrochlorothiazide; triamterene
Clinical Trial Phase	Trials
Completed	2
Unknown status	1
Withdrawn	1

Clinical Trial Sponsors for hydrochlorothiazide; triamterene

Sponsor Name

Sponsor Name for hydrochlorothiazide; triamterene
Sponsor	Trials
West China Hospital	1
University of California, Irvine	1
National Heart, Lung, and Blood Institute (NHLBI)	1

Sponsor Type

Sponsor Type for hydrochlorothiazide; triamterene
Sponsor	Trials
Other	4
U.S. Fed	2
NIH	1

Last updated: April 30, 2026

Clinical trials update, market analysis and projection for hydrochlorothiazide; triamterene

Hydrochlorothiazide; triamterene is a fixed-dose combination antihypertensive regimen used for hypertension and edema. The program is mature, with clinical activity largely limited to small comparator, bioavailability/bioequivalence, and regimen optimization work, while market performance is driven by guideline position, payer behavior, generic penetration, and formulary structure.

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What does the clinical evidence base look like today?

Clinical development pattern

For the hydorchlorothiazide/triamterene combination, the clinical evidence base is dominated by:

• Established efficacy in hypertension and fluid retention from earlier-era trials and routine clinical use.
• Post-launch studies that focus on pharmacokinetics, bioequivalence, and dosing/administration practices rather than new mechanism-of-action endpoints.
• Limited late-stage innovation because both components are off-patent in essentially all major jurisdictions and are widely available as generics.

Current trial footprint (what typically shows up in registries)

When combination products like this remain on study registries, the practical categories are:

• Bioequivalence studies for ANDA or generic launches.
• Small clinical studies comparing tablet formulations, fixed-dose schedules, or switch studies from separate dosing (hydrochlorothiazide plus triamterene given as two agents) to fixed-dose combination.
• Adherence and real-world regimen studies, which generate prescribing and persistence signals rather than label expansions.

No late-stage, mechanism-changing trials are characteristically present for this class because the combination does not represent a new therapeutic modality.

Safety and monitoring signals that dominate clinical practice

Hydrochlorothiazide and triamterene share class-relevant safety management that continues to drive enrollment and protocol design in any new studies:

• Electrolyte monitoring: potassium is a key decision variable because triamterene is potassium-sparing while hydrochlorothiazide is potassium-wasting.
• Renal function and creatinine monitoring.
• Monitoring for hypotension and volume status in older and comorbid populations.

These constraints affect protocol inclusion/exclusion criteria in even small studies and explain why most “new” clinical activity stays focused on tolerability and pharmacokinetics rather than outcomes trials.

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Where is the market anchored, and what drives demand?

Product role in therapy

Hydrochlorothiazide; triamterene functions as an affordable blood pressure and edema option, typically positioned when:

• Clinicians want diuretic therapy with reduced potassium loss risk versus hydrochlorothiazide monotherapy.
• Patients experience or are at risk for thiazide-associated hypokalemia.
• Cost-sensitive prescribing favors generics and fixed-dose convenience.

Core demand drivers

Key commercial demand drivers are structural rather than scientific:

1. Generic availability and price compression
   • The combination is widely generic, so volume growth is constrained by total addressable patients rather than differentiation.
2. Formulary and payer protocols
   • Diuretic combinations are often placed on low-tier formularies, with step therapy that maintains steady utilization.
3. Guideline-consistent use of thiazide-based diuretics
   • Thiazides and thiazide-like agents remain foundational in hypertension management, and fixed-dose diuretic combinations stay common in routine practice.
4. Safety-driven substitution patterns
   • When electrolyte concerns arise, clinicians choose potassium-sparing strategies within the diuretic class, supporting continued use.

Competitive landscape

Competition is primarily from:

• Thiazide monotherapies (cheaper, abundant).
• Alternative potassium-sparing diuretic combinations (for example, with amiloride or spironolactone/eplerenone depending on indication).
• Fixed-dose regimens with ACE inhibitors/ARBs or other antihypertensives, which increasingly capture clinician attention in brand-like and payer-favored packages, even if they are generic.

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What does market size and growth look like?

Market definition used for projection

Because hydorchlorothiazide/triamterene is a generic fixed-dose diuretic combination, most market reporting aggregates at broader levels:

• hypertension diuretics
• diuretic combinations
• cardiovascular (CV) generics with antihypertensive focus

A reliable market projection therefore must be grounded in macro assumptions:

• Total hypertension treated population growth (population aging and detection).
• Continued thiazide-based regimen share.
• Price erosion and generic mix effects.

Practical projection framework (volume-led, value-stable-to-declining)

For generics, the standard pattern is:

• Unit volumes grow slowly with treated prevalence and clinician practice.
• Value often declines in real terms due to ongoing price compression.

Accordingly, projections for this combination should emphasize:

• stable to modest unit growth
• flat to declining revenue over medium horizons in countries with aggressive generic pricing

Directional market outcome (base-case)

• Units: low single-digit CAGR potential driven by persistent diuretic use and older patient mix.
• Revenue: flat to negative real growth due to persistent generic price pressure.

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What is the outlook over the next 5 years?

Scenario set for business planning

Base case (most likely)

• Stable utilization as a low-cost diuretic combination.
• No material clinical label expansions.
• Ongoing generics competition keeps pricing tight.
• Revenue tracks largely with unit trends.

Downside case

• Share loss to:
  • thiazide-like diuretics and newer fixed-dose antihypertensive combinations
  • alternative potassium-sparing strategies
• More restrictive formularies or step therapy moving patients into other diuretic classes.

Upside case

• Expanded use in specific subpopulations where electrolyte balancing is a priority (older and comorbid patients).
• Sustained formulary inclusion and limited substitution by payers.

Key watch items that affect projection timing

• Changes in hypertension guideline emphasis that shift diuretic selection.
• Payer formulary updates affecting diuretic combination placement.
• Generic supply dynamics (if any major manufacturer exits or price floors rise, value can temporarily stabilize).

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Are there patent or exclusivity catalysts that could change the curve?

Patent reality for fixed-dose diuretic combinations

Hydrochlorothiazide and triamterene are long-established and are not expected to have enforceable new composition-of-matter exclusivity around the fixed-dose combination for typical markets. Commercial differentiation relies on:

• generic sourcing
• formulation stability and bioequivalence compliance
• manufacturing continuity

The implication for a 5-year outlook is straightforward: the market behavior is dominated by generic economics and formulary access rather than new patent-driven demand shocks.

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Commercial strategy implications: what should investors and R&D teams expect?

If you are underwriting the segment

• Treat this as a volume-driven generic in a mature CV category.
• Forecast revenue with conservative pricing assumptions and track unit volume by geography and payer tier.
• Focus on supply and formulary tenure, not on clinical innovation.

If you are evaluating new development

The realistic entry points are narrow:

• Reformulation or extended stability work that improves manufacturing economics.
• Bioequivalence lifecycle management for generic entrants.
• Combination strategy in specific patient subsets, but without likely label-changing trials at scale.

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Key Takeaways

• Hydorchlorothiazide; triamterene is a mature fixed-dose antihypertensive/diuretic combination with clinical activity dominated by bioequivalence and routine tolerability monitoring rather than new outcome-defining trials.
• Market performance is anchored in generic economics, formulary inclusion, and clinician use of thiazide-based diuretics.
• Base-case outlook is stable to modest unit growth with flat to declining real revenue over a 5-year horizon due to continued price compression.
• No patent-driven demand catalyst is expected to materially shift trajectory; the risk profile is primarily payer and competitive substitution dynamics.

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FAQs

1) What are the main clinical outcomes used to support this combination?

Hydrochlorothiazide/triamterene relies on established hypertension and edema efficacy evidence and, for newer entrants, on bioequivalence and safety/tolerability monitoring aligned with diuretic class requirements.

2) Why is the combination clinically used versus hydrochlorothiazide alone?

Triamterene is potassium-sparing and can reduce thiazide-associated potassium loss, improving electrolyte balance for patients where hypokalemia risk matters.

3) What drives prescribing in the current market?

Formulary placement, low cost, fixed-dose convenience, guideline-consistent diuretic therapy, and electrolyte management needs.

4) What is the biggest commercial risk for future revenue?

Ongoing generic price erosion and substitution to other diuretic strategies or fixed-dose antihypertensive regimens favored by payers.

5) Does the next 5 years depend on new patents?

No; the combination is mature and is projected to be driven primarily by generic availability, payer behavior, and market access.

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References

[1] National Institute for Health and Care Excellence (NICE). Hypertension in adults: diagnosis and management. London: NICE; (guideline recommendations relevant to diuretic use).
[2] World Health Organization (WHO). WHO Model List of Essential Medicines (diuretic inclusion and antihypertensive standard-of-care context).
[3] FDA. Bioequivalence studies and ANDA approval framework (regulatory basis for generic entry via bioequivalence).
[4] ClinicalTrials.gov. Hydrochlorothiazide; triamterene studies (registry record categories and recent activity patterns).