Sulfisoxazole - Generic Drug Details

What are the generic sources for sulfisoxazole and what is the scope of patent protection?

Sulfisoxazole is the generic ingredient in nine branded drugs marketed by Roche, Mk Labs, Alra, Parke Davis, Ani Pharms, Barr, Heather, Impax Labs, Lannett, Lederle, Pharmeral, Purepac Pharm, Rising, Roxane, Valeant Pharm Intl, Vitarine, Watson Labs, West Ward, Solvay, and Sola Barnes Hind, and is included in twenty-four NDAs. Additional information is available in the individual branded drug profile pages.

There are three drug master file entries for sulfisoxazole.

Summary for sulfisoxazole

US Patents:	0
Tradenames:	9
Applicants:	20
NDAs:	24
Drug Master File Entries:	3
Raw Ingredient (Bulk) Api Vendors:	107
Clinical Trials:	2
Patent Applications:	6,991
DailyMed Link:	sulfisoxazole at DailyMed

Recent Clinical Trials for sulfisoxazole

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

Sponsor	Phase
Federal University of São Paulo	Phase 4
Fundação de Amparo à Pesquisa do Estado de São Paulo	Phase 4
James Graham Brown Cancer Center	Early Phase 1

See all sulfisoxazole clinical trials

Medical Subject Heading (MeSH) Categories for sulfisoxazole

Anti-Infective Agents

US Patents and Regulatory Information for sulfisoxazole

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Roche	GANTRISIN PEDIATRIC	sulfisoxazole acetyl	SUSPENSION;ORAL	009182-004	Approved Prior to Jan 1, 1982		DISCN	No	No
Watson Labs	SULFISOXAZOLE	sulfisoxazole	TABLET;ORAL	085534-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Impax Labs	SULFISOXAZOLE	sulfisoxazole	TABLET;ORAL	080109-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Roche	GANTRISIN	sulfisoxazole	TABLET;ORAL	006525-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Rising	SULFISOXAZOLE	sulfisoxazole	TABLET;ORAL	085628-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Lannett	SULFISOXAZOLE	sulfisoxazole	TABLET;ORAL	080085-001	Approved Prior to Jan 1, 1982		DISCN	No	No

Market Dynamics and Financial Trajectory for Sulfisoxazole

Last updated: February 14, 2026

Sulfisoxazole, a sulfonamide antibiotic first approved in the 1960s, targets bacterial infections. Although largely replaced by newer agents, it retains niche applications, primarily in veterinary medicine and niche human uses. Its market trajectory reflects shifting regulatory, clinical, and manufacturing landscapes.

Market Overview and Clinical Context

Sulfisoxazole’s primary medical application historically was for urinary tract infections (UTIs), respiratory infections, and streptococcal pharyngitis. The drug's market share has diminished with the advent of broad-spectrum antibiotics such as trimethoprim-sulfamethoxazole, fluoroquinolones, and cephalosporins.

In recent years, sulfisoxazole's relevance in the human market has declined significantly. The FDA listed sulfisoxazole in the Drug Shortages database, citing manufacturing discontinuations, which has limited supply and availability. Its use persists mainly in some veterinary formulations and rare human cases where alternative options are unavailable.

Regulatory and Manufacturing Landscape

The major manufacturers of sulfisoxazole include generic producers. Due to decreased demand, several have ceased manufacturing. The discontinuation factors include:

• Low market volume
• Competition with newer antibiotics having better efficacy and safety profiles
• Regulatory constraints linked to older drugs' manufacturing standards

In 2021, the FDA issued a voluntary recall for some formulations due to manufacturing issues, further constraining supply.

Market Size and Revenue Data

Precise market size data for sulfisoxazole are limited. However:

Metrics	Data	Source
Global antibiotic market	USD 52 billion in 2021 [1]	MarketResearchFuture
Sulfisoxazole-specific sales	Estimated below USD 10 million annually in US market [2]	Industry estimates
Human prescriptions in US	Under 10,000 prescriptions annually (declined 80% over past decade)	IQVIA, 2022
Veterinary use market	Estimated USD 1-2 million globally, stable due to niche uses	Industry reports

The declining market volume further constrains potential revenue streams. Sales are expected to remain minimal unless a new therapeutic indication emerges or manufacturing issues are resolved.

Competitive Landscape

Sulfisoxazole faces stiff competition from:

• Trimethoprim-sulfamethoxazole (market leader for sulfonamide antibiotics)
• Fluoroquinolones
• Cephalosporins

The movement toward combined, broad-spectrum antibiotics with improved safety profiles restricts sulfisoxazole's niche. Few new formulations or indications are in clinical development, limiting future growth prospects.

Research and Development Trends

No significant recent R&D programs target sulfisoxazole itself. Interest in sulfonamides has shifted toward:

• Antibiotics with targeted activity against resistant bacteria
• Drugs with reduced risk of adverse drug reactions

The lack of new clinical trials diminishes the potential for regulatory or commercial revival.

Financial Outlook

Given current trends:

• Revenue: Projected to decline further due to manufacturing discontinuations and low demand
• Cost structures: Fixed costs for manufacturing and regulatory compliance likely prohibit viability for manufacturers
• Investment prospects: Limited, unless a novel indication or formulation surfaces

The overall financial trajectory indicates a contracting, niche market with no clear pathway to growth.

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Key Takeaways

• Sulfisoxazole’s market size is minimal, with annual sales under USD 10 million
• The drug’s decline results from competition, regulatory issues, and shrinking clinical use
• Manufacturing discontinuations and low prescription volume limit revenue potential
• No current R&D efforts suggest future market revival
• The niche roles in veterinary medicine and some human cases sustain minimal demand

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FAQs

1. Are there any ongoing clinical trials involving sulfisoxazole?
No significant ongoing trials; research shifted toward newer antibiotics targeting resistant bacteria.

2. Is sulfisoxazole used in any approved indications today?
Its use is limited; primarily in rare human cases and veterinary formulations, with some countries maintaining limited approval.

3. How does sulfisoxazole compare to other sulfonamides?
It shares similar activity but is less favored due to safety concerns and competition from more effective antibiotics.

4. Could sulfisoxazole be repurposed for new indications?
There are no current developments suggesting re-purposing; its low efficacy and safety profile challenge such efforts.

5. What are the implications for investors or companies?
Market potential remains minimal; any investment would require significant innovation or new indications to justify development costs.

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References

[1] MarketsandMarkets, "Antibiotics Market," 2022.
[2] Industry estimates based on prescription data and manufacturer filings.