CLINICAL TRIALS PROFILE FOR SULFAMETHOXAZOLE

505(b)(2) Clinical Trials for SULFAMETHOXAZOLE

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	NCT03431168 ↗	A Novel Regimen to Prevent Malaria and STI in Pregnant Women With HIV	Active, not recruiting	University of Alabama at Birmingham	Phase 2	2018-03-07	More than 3 billion people worldwide are at risk of acquiring malaria and pregnant women living with HIV in Africa are at particular risk. An effective prophylaxis regimen capable of preventing malaria and other common perinatal infections would have great potential to improve adverse birth outcomes. The purpose of this randomized controlled trial is to evaluate a new combination prophylaxis regimen in pregnant women with HIV in Cameroon to determine its efficacy and safety.
OTC	NCT05055544 ↗	Bearberry in the Treatment of Cystitis	Not yet recruiting	University of Pecs	N/A	2021-10-01	The goal of this study is to assess the efficacy of bearberry in uncomplicated cystitis. Uncomplicated cystitis is a disease related to the infection of the urinary bladder. Typical symptoms are dysuria, urinary urgency, and frequent voiding of small volumes. Urinary tract infections are frequent in women, usually treated with antibiotics, since the disease is usually caused by bacteria. Fosfomycin is a frequently used antibiotic for the treatment of uncomplicated cystitis. This medicine is typically prescribed by MDs. However, since uncomplicated cystitis is quite frequent, not all patients visit the doctor when experiencing the symptoms of this disease. The use of over-the-counter products (medicines and food supplements) to alleviate the symptoms is common. One of the most frequently used medicinal plants for this purpose is bearberry. Bearberry is a medicinal plant traditionally used for the treatment of cystitis. Its use is accepted by the European Medicine Agency as traditional herbal medicinal product for relief of symptoms of mild recurrent lower urinary tract infections such as burning sensation during urination and/or frequent urination in women. Although the experience gained during the traditional use and the laboratory experiments support the supposed beneficial effect of bearberry, its clinical efficacy has not been confirmed in well-designed clinical trials in comparison with standard antibiotic therapy. In this study, the efficacy of bearberry will be assessed in comparison with fosfomycin. Premenopausal women experiencing the symptoms of uncomplicated cystitis will be randomly divided into two groups. Since it will be a double-blind trial, neither the participants nor the experimenters will know who is receiving a particular treatment. In group A, patients will receive a single dose of fosfomycin powder dissolved in water and 2 placebo tablets three times a day for 7 days. In group B, patients will receive a single dose of placebo powder dissolved in water and 2 bearberry tablets three times a day for 7 days. At the beginning of the study (day 0) and on day 7, patients will be asked to fill in a questionnaire concerning their symptoms. At the same times, urine specimens will be collected to inspect the presence of bacteria in the urine. The primary goal of the trial is to assess the improvement of symptoms of uncomplicated cystitis after 7 days of treatment with the intention to analyze whether treatment with bearberry is at least as effective as fosfomycin therapy is. This will be achieved by using a validated questionnaire (Acute Cystitis Symptom Score). The presence of bacteria in urine and the frequency and severity of side effects will also be recorded and compared. During a 90-days follow-up of this study, the recurrence of urinary tract infections will be analyzed. This study will deliver important data on the efficacy and safety of bearberry in the treatment of uncomplicated cystitis.

All Clinical Trials for SULFAMETHOXAZOLE

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00000640 ↗	A Phase III Comparative Study of Dapsone / Trimethoprim and Clindamycin / Primaquine Versus Sulfamethoxazole / Trimethoprim in the Treatment of Mild-to-Moderate PCP in Patients With AIDS	Completed	Glaxo Wellcome	Phase 3	1969-12-31	To evaluate the effectiveness of two oral treatments for mild to moderate Pneumocystis carinii pneumonia (PCP): dapsone/trimethoprim or clindamycin/primaquine as compared to a standard treatment program of sulfamethoxazole/trimethoprim (SMX/TMP) to assess the tolerance of these two alternative treatments as compared to the standard treatment of SMX/TMP. Per 09/09/92 amendment, to assess the efficacy and tolerance of these two alternative treatments in patients who are intolerant to SMX/TMP. The type of treatment being studied has the advantages of wide applicability throughout the world (including developing countries) and low cost. An oral treatment is more accessible to patients than drugs given by injection or by inhalation.
NCT00000640 ↗	A Phase III Comparative Study of Dapsone / Trimethoprim and Clindamycin / Primaquine Versus Sulfamethoxazole / Trimethoprim in the Treatment of Mild-to-Moderate PCP in Patients With AIDS	Completed	Jacobus Pharmaceutical	Phase 3	1969-12-31	To evaluate the effectiveness of two oral treatments for mild to moderate Pneumocystis carinii pneumonia (PCP): dapsone/trimethoprim or clindamycin/primaquine as compared to a standard treatment program of sulfamethoxazole/trimethoprim (SMX/TMP) to assess the tolerance of these two alternative treatments as compared to the standard treatment of SMX/TMP. Per 09/09/92 amendment, to assess the efficacy and tolerance of these two alternative treatments in patients who are intolerant to SMX/TMP. The type of treatment being studied has the advantages of wide applicability throughout the world (including developing countries) and low cost. An oral treatment is more accessible to patients than drugs given by injection or by inhalation.
NCT00000640 ↗	A Phase III Comparative Study of Dapsone / Trimethoprim and Clindamycin / Primaquine Versus Sulfamethoxazole / Trimethoprim in the Treatment of Mild-to-Moderate PCP in Patients With AIDS	Completed	National Institute of Allergy and Infectious Diseases (NIAID)	Phase 3	1969-12-31	To evaluate the effectiveness of two oral treatments for mild to moderate Pneumocystis carinii pneumonia (PCP): dapsone/trimethoprim or clindamycin/primaquine as compared to a standard treatment program of sulfamethoxazole/trimethoprim (SMX/TMP) to assess the tolerance of these two alternative treatments as compared to the standard treatment of SMX/TMP. Per 09/09/92 amendment, to assess the efficacy and tolerance of these two alternative treatments in patients who are intolerant to SMX/TMP. The type of treatment being studied has the advantages of wide applicability throughout the world (including developing countries) and low cost. An oral treatment is more accessible to patients than drugs given by injection or by inhalation.

Clinical Trial Conditions for SULFAMETHOXAZOLE

Condition Name

Condition Name for SULFAMETHOXAZOLE
Intervention	Trials
HIV Infections	36
Pneumonia, Pneumocystis Carinii	27
Urinary Tract Infections	10

Condition MeSH

Condition MeSH for SULFAMETHOXAZOLE
Intervention	Trials
HIV Infections	39
Infections	39
Pneumonia	38

Clinical Trial Locations for SULFAMETHOXAZOLE

Trials by Country

Trials by Country for SULFAMETHOXAZOLE
Location	Trials
United States	413
China	18
Canada	17
France	16
Mexico	7

Trials by US State

Trials by US State for SULFAMETHOXAZOLE
Location	Trials
California	33
New York	25
Illinois	24
Texas	22
Pennsylvania	20

Clinical Trial Progress for SULFAMETHOXAZOLE

Clinical Trial Phase

Clinical Trial Phase for SULFAMETHOXAZOLE
Clinical Trial Phase	Trials
PHASE4	8
PHASE2	3
PHASE1	1

Clinical Trial Status

Clinical Trial Status for SULFAMETHOXAZOLE
Clinical Trial Phase	Trials
Completed	93
Recruiting	19
Terminated	16

Clinical Trial Sponsors for SULFAMETHOXAZOLE

Sponsor Name

Sponsor Name for SULFAMETHOXAZOLE
Sponsor	Trials
National Institute of Allergy and Infectious Diseases (NIAID)	32
M.D. Anderson Cancer Center	10
Glaxo Wellcome	8

Sponsor Type

Sponsor Type for SULFAMETHOXAZOLE
Sponsor	Trials
Other	210
NIH	53
Industry	43

Sulfamethoxazole Clinical Trials Update, Market Outlook, and Patent/Competition Risk Projection (2026)

Last updated: July 30, 2026

Sulfamethoxazole (SMX) is an off-patent, widely generics-supplied antibiotic with limited sponsor-led new-drug value creation. Clinical activity is concentrated in (1) combination regimens (most commonly with trimethoprim), (2) dose optimization and formulation/PK studies in specific populations, and (3) post-approval safety, resistance surveillance, and real-world effectiveness work. Market risk is dominated by low-cost generic supply, periodic shortages, and stewardship-driven demand compression rather than exclusivity cliffs.

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What clinical trials are ongoing or recently completed for sulfamethoxazole (SMX) in 2025–2026?

Which study types drive the current sulfamethoxazole pipeline

• Combination studies: SMX is rarely studied as monotherapy in modern development programs; most clinical endpoints relate to SMX-trimethoprim (TMP-SMX).
• PK/PD and special population trials: renal impairment, pediatrics, pregnancy exposures, and burn or critical care settings are common.
• Formulation and bioavailability: oral solid form equivalence, suspensions, and pediatric-friendly presentations.
• Resistance and outcomes: observational cohorts and pragmatic interventional designs evaluate pathogen coverage, duration of therapy, and adverse event profiles.

Where new clinical evidence is most likely to change practice

• Dosing strategies: trials that refine dosing in renal impairment or in obesity and extremes of age can support label changes or guideline updates.
• Duration optimization: shorter vs traditional courses for defined indications can influence payer policy and antibiotic utilization.
• Safety refinement: hypersensitivity, Stevens-Johnson syndrome risk mitigation, and renal toxicity monitoring protocols.

Actionability note: For SMX (off-patent), “pipeline value” is usually about line extensions (formulation, pediatric dosing, use in novel infections, or new guideline-aligned regimens) rather than new chemical entity approvals.

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What indications and endpoints matter most for sulfamethoxazole trial results?

Top indication clusters in current-generation evidence

• Urinary tract infections and prostatitis
• Skin and soft tissue infections
• Respiratory infections where TMP-SMX remains in use
• Opportunistic infection prophylaxis and treatment (HIV and transplant-related contexts)
• Pneumocystis jirovecii pneumonia (PCP): dosing regimen and safety monitoring studies

Endpoints that trend in trial publications

• Clinical cure or response rates at end of therapy
• Microbiologic eradication for target pathogens
• Time-to-symptom improvement
• Adverse event frequency, including rash, GI intolerance, and renal lab shifts
• Discontinuation due to intolerance

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How does sulfamethoxazole compare with alternatives in current trials and real-world use?

Clinical competitiveness vs other oral antibiotics

• For UTIs and uncomplicated infections: fluoroquinolones and nitrofurantoin often compete for empiric or guideline-driven use.
• For MRSA/skin infections: doxycycline, clindamycin, and linezolid frequently compete, with TMP-SMX as a common oral option.
• For PCP prophylaxis/treatment: SMX-containing regimens remain a central comparator to alternative prophylaxis strategies when intolerance occurs.

Where SMX retains a practical advantage

• Broad clinician familiarity and predictable bactericidal activity in TMP-SMX–responsive pathogens
• Availability in multiple generic forms
• Long-standing dosing familiarity enabling easier protocol deployment

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What is the sulfamethoxazole market size and growth profile through 2027?

Market profile: why growth is limited

• SMX is generic and fungible in many indications.
• Demand is shaped by stewardship, antimicrobial resistance, payer restrictions, and guideline shifts.
• Supply chain volatility can drive short-cycle price movements without structural growth.

What typically drives unit demand

• Infectious disease incidence cycles
• PCP prophylaxis need in HIV and immunocompromised populations
• Regional prescribing patterns and formulary access

What typically drives revenue volatility

• Generic price compression in normal conditions
• Temporary shortages and distribution constraints
• Label or safety messaging changes that affect prescribing

Projection logic for SMX (generic, mature antibiotic): low single-digit growth is typical for global volumes; value growth tends to track inflation and episodic supply disruptions more than new utilization.

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What generic and supply dynamics define sulfamethoxazole competition?

Generic manufacturing structure

• Multiple manufacturers supply oral tablets/capsules and suspension formulations in most markets.
• Competition often focuses on acquisition cost, distribution reliability, and regulatory quality metrics rather than differentiation.

Market share mechanics

• Formulary placement: drives stable baseline volume.
• Contract pharmacy distribution: can lock in purchasing.
• National tender cycles: in some countries, determine who wins supply.

Key risk: shortages

• Antibiotic shortage events can create temporary pricing power for a subset of suppliers, then revert after capacity normalizes.

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When does sulfamethoxazole lose exclusivity, and are there any exclusivity-driven earnings cliffs?

Exclusivity status

• SMX itself is off-patent in major jurisdictions due to age of active ingredient commercialization.
• Remaining market protection typically comes from formulation-specific patents, method-of-use patents (rare for off-patent APIs), pediatric exclusivity tied to specific sponsors, or regulatory exclusivities for combination or novel dosage forms.

Practical implication

• There is no single “exclusivity cliff” event for SMX comparable to novel biologics or branded small molecules.
• Competitive entry risk is persistent and largely determined by manufacturing access and regulatory approvals rather than patent expiration.

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What patents protect sulfamethoxazole today: active ingredient, formulations, or uses?

Patent protection profile for SMX

• Active ingredient: historically expired.
• Formulation/device/combination patents: may exist for specific dosage forms, manufacturing methods, or pediatric-friendly presentations, but generally do not prevent generic competition broadly.

How to evaluate patent strength in practice

• Look for patents tied to:
  • Specific dose strengths and release profiles (immediate vs modified-release, if any)
  • Pediatric suspension manufacturing and stability
  • Specific combination fixed-dose products (TMP-SMX tablets or suspension formats)
  • Narrow method-of-use claims in defined indications

Business reality for generic SMX: even when formulation patents exist, generic entrants can often avoid them by choosing non-infringing manufacturing routes or equivalent dosage forms.

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What is the Orange Book status of sulfamethoxazole (SMX) and related combinations?

Typical Orange Book pattern for SMX

• Multiple ANDA approvals for SMX and TMP-SMX oral products.
• Orange Book listings generally include expired patents and a long tail of formulation-specific patents (where they exist).
• FDF holders and ANDA filers often carry a complex web of patent listings, but the active ingredient itself usually has no enforceable life left.

Why this matters

• In the SMX market, competitive timing is usually governed by:
  • Patent-by-patent enforceability
  • ANDA design-around and manufacturing equivalence
  • exclusivity tied to specific NDA/ANDA applications (when present)

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Has there been Paragraph IV litigation or ANDA challenges for sulfamethoxazole?

Expected litigation posture

• Patent challenges for off-patent antibiotics are common in fixed-dose combinations when formulation or method-of-use patents remain.
• Settlements, if any, tend to be narrow and product-specific, not industry-wide.

What would be economically meaningful

• A successful challenge that affects a large label-protected product line (e.g., a specific TMP-SMX suspension strength used in pediatrics).
• A settlement that accelerates generic market entry in high-volume strengths.

Actionability note: For SMX, litigation typically affects pricing at the margin by changing supplier count in specific SKUs.

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What FDA regulatory pathway issues affect sulfamethoxazole generic entry?

ANDA chemistry and bioequivalence

• For oral solids: equivalence testing for rate and extent of absorption
• For suspensions: stability, particle size, and re-dispersibility performance

Quality and compliance factors

• Sterility is not applicable for oral SMX, but manufacturing controls are central.
• Bioequivalence for suspensions is a common friction point.

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How does sulfamethoxazole perform commercially versus other antibiotics used for similar infections?

Commercial comparisons

• Versus newer oral agents, SMX/TMP-SMX often sells at lower prices per treatment course due to generic parity.
• Versus older off-patent alternatives (nitrofurantoin, amoxicillin-clavulanate), competitive outcomes hinge on:
  • formulary preference
  • resistance patterns
  • tolerability profiles

Payer and stewardship impact

• Payers increasingly drive narrower empiric indications, which can reduce the total addressable prescribing universe even if SMX retains clinical utility.

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Market projection: what is the 2026–2027 revenue outlook for sulfamethoxazole?

Projection assumptions

• Stable baseline demand in chronic/prophylaxis indications
• Moderate volume growth in line with infection incidence
• Price decline continuing in most geographies due to generic competition
• Short-cycle spikes from shortages possible

Revenue outlook directionally

• Global value: likely flat to low growth through 2027, with episodic volatility.
• Unit volumes: likely low single-digit growth, driven by patient population needs and healthcare utilization, partially offset by stewardship restrictions.

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Which companies are most exposed to sulfamethoxazole demand and pricing shifts?

Exposure map

• Manufacturers with high share in TMP-SMX oral lines: most sensitive to price compression and tender outcomes.
• Suppliers concentrated in pediatric suspension strengths: sensitive to formulation-specific scrutiny and periodic supply interruptions.
• Brand-adjacent distributors (if any): exposed mainly through margin compression and contract renewals.

Actionability note: In mature antibiotic markets, the key differentiators are supply reliability and SKU-level compliance, not IP strategy.

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Key Takeaways

1. Sulfamethoxazole is off-patent; competitive advantage is structural (manufacturing scale, regulatory execution, and supply reliability), not exclusivity.
2. Current clinical evidence is dominated by combination regimens (TMP-SMX) and optimization studies focused on dosing, PK, special populations, and safety monitoring.
3. Market growth is constrained by generic fungibility and stewardship pressure; revenue is more sensitive to price cycles and shortage events than to new demand creation.
4. Patent-driven earnings cliffs are unlikely at the active ingredient level; any remaining protection is typically product- and formulation-specific with limited industry-wide impact.

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FAQs

1) Is sulfamethoxazole used for PCP prophylaxis, and are there new dosing studies?
Recent clinical work focuses on optimizing dosing and monitoring in immunocompromised populations, usually within TMP-SMX regimens.

2) What are the most common reasons TMP-SMX (sulfamethoxazole) prescriptions are discontinued?
Hypersensitivity reactions, GI intolerance, and renal function changes are typical discontinuation drivers.

3) How does generic substitution affect sulfamethoxazole pricing in major markets?
Generic substitution usually drives persistent price compression, with brief pricing spikes during supply constraints.

4) Are there formulation-specific patents that can slow generic entry for TMP-SMX suspensions?
Where they exist, they tend to be narrow to specific strengths, manufacturing methods, or stability-related claims.

5) What resistance trends most affect sulfamethoxazole utility?
Rising resistance in relevant bacterial species reduces empirical coverage and can shift guideline preference toward alternatives.

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References

1. U.S. Food and Drug Administration. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. (Accessed 2026).
2. FDA. Guidance for Industry: Bioequivalence Studies Submitted in Support of Approval of Generic Drugs. (Accessed 2026).
3. World Health Organization. Antimicrobial resistance surveillance and stewardship resources. (Accessed 2026).