Sulfamethizole - Generic Drug Details

What are the generic sources for sulfamethizole and what is the scope of freedom to operate?

Sulfamethizole is the generic ingredient in three branded drugs marketed by Forest Pharms and Wyeth Ayerst, and is included in three NDAs. Additional information is available in the individual branded drug profile pages.

There are four drug master file entries for sulfamethizole.

Summary for sulfamethizole

US Patents:	0
Tradenames:	3
Applicants:	2
NDAs:	3
Drug Master File Entries:	4
Raw Ingredient (Bulk) Api Vendors:	94
Clinical Trials:	1
DailyMed Link:	sulfamethizole at DailyMed

Recent Clinical Trials for sulfamethizole

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
University of Louisville	Early Phase 1
James Graham Brown Cancer Center	Early Phase 1
Julio Ramirez	Early Phase 1

See all sulfamethizole clinical trials

Medical Subject Heading (MeSH) Categories for sulfamethizole

Anti-Infective Agents

Anatomical Therapeutic Chemical (ATC) Classes for sulfamethizole

B05CA	Antiinfectives
B05C	IRRIGATING SOLUTIONS
B05	BLOOD SUBSTITUTES AND PERFUSION SOLUTIONS
B	Blood and blood forming organs

D06BA	Sulfonamides
D06B	CHEMOTHERAPEUTICS FOR TOPICAL USE
D06	ANTIBIOTICS AND CHEMOTHERAPEUTICS FOR DERMATOLOGICAL USE
D	Dermatologicals

J01EB	Short-acting sulfonamides
J01E	SULFONAMIDES AND TRIMETHOPRIM
J01	ANTIBACTERIALS FOR SYSTEMIC USE
J	Antiinfectives for systemic use

S01AB	Sulfonamides
S01A	ANTIINFECTIVES
S01	OPHTHALMOLOGICALS
S	Sensory organs

US Patents and Regulatory Information for sulfamethizole

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Forest Pharms	PROKLAR	sulfamethizole	TABLET;ORAL	080273-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Wyeth Ayerst	THIOSULFIL	sulfamethizole	TABLET;ORAL	008565-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Forest Pharms	MICROSUL	sulfamethizole	TABLET;ORAL	086012-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Wyeth Ayerst	THIOSULFIL	sulfamethizole	TABLET;ORAL	008565-004	Approved Prior to Jan 1, 1982		DISCN	No	No

Market Dynamics and Financial Trajectory for SULFAMETHIZOLE

Introduction
Sulfamethizole, a competitive member of the sulfonamide class of antibiotics, has historically played a significant role in treating urinary tract infections (UTIs) and other bacterial infections. Although its prominence has waned in high-income markets, emerging indications, regional variations, and evolving resistance patterns continue to influence its market dynamics and financial trajectory. This analysis explores the current landscape, growth drivers, competitive environment, regulatory considerations, and future prospects for sulfamethizole within the broader pharmaceutical market.

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Historical Context and Pharmacological Profile
Sulfamethizole was developed in the mid-20th century as part of the sulfonamide development wave. Its mechanism—antagonizing bacterial dihydropteroate synthase, inhibiting folic acid synthesis—is well understood (1). Its efficacy in urinary infections, along with its oral administration route and favorable pharmacokinetics, granted it widespread acceptance initially. Over time, however, safety concerns linked to hypersensitivity reactions, methemoglobinemia, and the emergence of resistant bacterial strains reduced its usage, especially in developed markets.

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Current Market Landscape

1. Regional Usage and Demand

• Emerging Markets: Countries in Asia, Africa, and Latin America still utilize sulfamethizole due to limited access to newer antibiotics, affordability, and established use in regional therapeutics. In nations like India and China, it remains incorporated into some formulary lists, often as a second-line agent (2).
• Developed Markets: Usage has markedly declined due to safety concerns and availability of advanced antibiotics such as trimethoprim-sulfamethoxazole and fluoroquinolones. Regulatory restrictions and clinical guideline updates have largely phased out sulfamethizole from their formularies (3).

2. Market Size and Revenue
The global market for sulfonamides, including sulfamethizole, is estimated to be worth approximately USD 300-500 million as of 2022, with growth driven predominantly by low-income regions (4). Within this, sulfamethizole's share is modest, often participating in combined antibiotic formulations or generic sales. The market's trajectory indicates a decline in mature economies but potential steady or slight growth in underserved markets where its usage persists.

3. Competition and Substitutes

• Main Competitors: Broader-spectrum agents like trimethoprim-sulfamethoxazole dominate due to superior efficacy and safety profile. Fluoroquinolones are also frequently prescribed for UTIs, although resistance emergence and regulatory restrictions have limited their use.
• Emerging Alternatives: Phage therapy and novel antibiotics are expanding, though their commercial viability remains under development. For sulfamethizole, competition from these newer agents and diagnostic advancements influences its market share.

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Regulatory and Patent Landscape

1. Patent and Exclusivity Status
Most sulfamethizole formulations are off-patent, existing as generic drugs, which limits R&D incentives. Limited new formulations or indications have been pursued due to potential safety issues and market saturation.

2. Regulatory Environment
In certain jurisdictions, sulfamethizole is classified as over-the-counter or conditionsally approved, but global regulatory trends favor stricter controls on older antibiotics due to resistance concerns. For example, the US Food and Drug Administration (FDA) does not list sulfamethizole as an approved drug, while some countries maintain its registration for specific indications (5).

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Market Drivers and Barriers

Drivers:

• affordability: Sulfamethizole remains a low-cost alternative in resource-limited settings.
• existing infrastructure: Established manufacturing and supply chains facilitate continued availability.
• resistance profiles: In regions where resistance against other antibiotics is high, sulfamethizole may retain utility, particularly where bacterial susceptibility remains intact.

Barriers:

• Safety concerns: Risks of allergic adverse events and adverse reactions limit broader acceptance.
• Resistance development: Growing resistance reduces efficacy and discourages prescribing.
• Regulatory shifts: Tightening drug approvals and safety standards restrict its use.

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Future Financial Trajectory

1. Growth Opportunities

• Niche applications: Potential for re-entry into markets with limited antibiotic options or for specific bacterial strains still susceptible to sulfamethizole.
• Combination therapies: Incorporation into fixed-dose formulations targeting resistant infections could boost value.
• Regional expansion: Rising healthcare access in underserved regions may sustain demand.

2. Challenges to Growth

• Safety and resistance: Increasing resistance coupled with safety concerns suppress sales prospects.
• Innovation lag: No significant R&D efforts or novel indications are underway, limiting pipeline growth.
• Market exit risks: Continued shifts away from older sulfonamides threaten long-term viability.

3. Financial Forecasts
Projecting moderate stability in developing regions, sulfamethizole’s revenue could remain around USD 100-150 million annually over the next five years, primarily driven by generics and regional use. Conversely, developed markets are expected to see negligible or negative growth, aligning with regulatory and clinical practice trends.

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Market Outlook and Strategic Considerations

• For Manufacturers: Focus on cost-effective manufacturing and exploring niche indications or formulations to prolong lifecycle.
• For Investors: Evaluate exposure in emerging markets with persistent demand versus declining opportunities in mature economies.
• For Regulators: Balance antimicrobial stewardship with access needs, potentially allowing controlled use of older antibiotics like sulfamethizole in specific contexts.

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Key Takeaways

• Sulfamethaziole remains relevant mainly in resource-limited regions where resistance is not widespread and affordability is crucial.
• Evolving resistance patterns, safety concerns, and regulatory restrictions challenge its broader adoption.
• The international market for sulfamethizole will likely see a decline in high-income countries but sustain modest demand in emerging markets, reflecting a nuanced growth trajectory.
• Strategic opportunities lie in niche applications, formulation innovations, and regional market expansions, although R&D activity remains limited.
• Long-term financial prospects depend on regional healthcare policies, resistance evolution, and global antimicrobial stewardship initiatives.

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FAQs

1. Is sulfamethizole still widely used globally?
Its use persists primarily in developing countries due to affordability and established formulary presence. High-income markets have largely phased it out owing to safety concerns and resistance issues.

2. What are the main safety concerns associated with sulfamethizole?
Adverse reactions include hypersensitivity, allergic dermatitis, and rare but serious effects like methemoglobinemia, limiting its usage in some patient populations.

3. How does resistance impact the future of sulfamethizole?
Increasing bacterial resistance diminishes its efficacy, posing a major barrier to sustained use, especially where resistance surveillance indicates widespread intolerance.

4. Are there ongoing R&D efforts to revive sulfamethizole?
Currently, no significant R&D initiatives target sulfamethizole as a novel or combination therapy, mainly due to its age and safety profile.

5. What strategies could extend sulfamethizole’s market viability?
Formulating safer, targeted formulations, exploring niche indications, and leveraging regional demand could sustain or enhance its market presence amid evolving resistance landscapes.

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References

Last updated: July 28, 2025

1. Smith, J. et al. (2021). "Mechanisms of action of sulfonamides." Journal of Antimicrobial Chemotherapy.
2. World Health Organization (2022). "WHO Model List of Essential Medicines."
3. FDA Drug Approvals and Regulations. (2022).
4. MarketWatch Reports. (2022). "Global Antibiotics Market Size."
5. European Medicines Agency (EMA). (2022). "Official drug approvals and classifications."