SULFINPYRAZONE - Generic Drug Details

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

Sulfinpyrazone is the generic ingredient in two branded drugs marketed by Novartis, Barr, Ivax Pharms, Par Pharm, Vangard, and Watson Labs, and is included in nine NDAs. Additional information is available in the individual branded drug profile pages.

There are four drug master file entries for sulfinpyrazone.

Summary for SULFINPYRAZONE

US Patents:	0
Tradenames:	2
Applicants:	6
NDAs:	9
Drug Master File Entries:	4
Raw Ingredient (Bulk) Api Vendors:	80
Clinical Trials:	3
Patent Applications:	7,567
DailyMed Link:	SULFINPYRAZONE at DailyMed

Recent Clinical Trials for SULFINPYRAZONE

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

Sponsor	Phase
Fundação de Amparo à Pesquisa do Estado de São Paulo	Phase 4
Federal University of São Paulo	Phase 4
China Medical University Hospital	Phase 2

See all SULFINPYRAZONE clinical trials

Medical Subject Heading (MeSH) Categories for SULFINPYRAZONE

Uricosuric Agents

Anatomical Therapeutic Chemical (ATC) Classes for SULFINPYRAZONE

M04AB	Preparations increasing uric acid excretion
M04A	ANTIGOUT PREPARATIONS
M04	ANTIGOUT PREPARATIONS
M	Musculo-skeletal system

US Patents and Regulatory Information for SULFINPYRAZONE

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Barr	SULFINPYRAZONE	sulfinpyrazone	CAPSULE;ORAL	087666-001	Sep 17, 1982		DISCN	No	No
Ivax Pharms	SULFINPYRAZONE	sulfinpyrazone	TABLET;ORAL	087769-001	Jun 1, 1982		DISCN	No	No
Par Pharm	SULFINPYRAZONE	sulfinpyrazone	CAPSULE;ORAL	088934-001	Sep 6, 1985		DISCN	No	No
Watson Labs	SULFINPYRAZONE	sulfinpyrazone	TABLET;ORAL	087667-001	May 26, 1982		DISCN	No	No
Novartis	ANTURANE	sulfinpyrazone	TABLET;ORAL	011556-003	Approved Prior to Jan 1, 1982		DISCN	No	No
Novartis	ANTURANE	sulfinpyrazone	CAPSULE;ORAL	011556-004	Approved Prior to Jan 1, 1982		DISCN	Yes	No

Sulfinpyrazone Market Dynamics, Patent Status, and Financial Trajectory

Last updated: August 8, 2026

Sulfinpyrazone is an obsolete uricosuric drug with no meaningful current U.S. commercial market. The former Anturane brand lost commercial relevance after treatment guidelines shifted toward allopurinol, febuxostat, and other urate-lowering therapies. Public sources do not show an active FDA marketing program, current Orange Book exclusivity, material patent protection, or a separately reported revenue stream for sulfinpyrazone. Its economic value is limited to historical market analysis, legacy product rights, and potential use in narrow international or compounding channels.

What is sulfinpyrazone and how was it commercialized?

Sulfinpyrazone is a pyrazolidine derivative that increases renal uric acid excretion. It was marketed primarily for chronic gout and hyperuricemia under the Anturane brand. The drug also attracted interest as an antiplatelet therapy, but cardiovascular use did not develop into a durable commercial market.

Attribute	Sulfinpyrazone
Active ingredient	Sulfinpyrazone
Pharmacologic class	Uricosuric agent
Former brand	Anturane
Historical manufacturer	Geigy, later associated with Ciba-Geigy
Main indication	Chronic gout and hyperuricemia
Dosage forms	Oral tablets, historically 100 mg and 200 mg strengths
Current U.S. status	No material active commercial market identified
Regulatory position	Legacy product; no current exclusivity value identified
Main historical competitors	Probenecid, allopurinol, colchicine
Modern competitors	Allopurinol, febuxostat, pegloticase, lesinurad where available

Sulfinpyrazone required adequate renal function and was not suitable for every gout patient. Its uricosuric mechanism also created practical limitations, including the need to manage urinary uric acid and the risk of uric acid crystallization in susceptible patients. The American College of Rheumatology’s current treatment framework places allopurinol as the preferred first-line urate-lowering therapy for most patients, reducing the clinical role available to older uricosuric drugs.[1]

When did sulfinpyrazone lose exclusivity and commercial momentum?

Sulfinpyrazone’s patent and exclusivity value expired decades ago. The product was introduced in the mid-20th century, so any composition-of-matter patent associated with the original molecule would have expired long before the modern 20-year patent term became relevant. Any later formulation or method-of-use patents would also have reached the end of their enforceable terms by the time the brand disappeared from routine U.S. prescribing.

A precise single expiration date is not commercially meaningful because the original product predates the modern patent-recording framework and because public sources do not identify a current patent family that protects marketed sulfinpyrazone.

Historical exclusivity timeline

Period	Market event	Commercial effect
Mid-20th century	Introduction of sulfinpyrazone and Anturane	Originator-controlled market
1970s-1980s	Expansion of interest in uricosuric and antiplatelet uses	Broader clinical visibility, but limited long-term differentiation
1980s-1990s	Growth of allopurinol as chronic urate-lowering therapy	Reduced reliance on sulfinpyrazone
Late 20th century	Generic and low-cost alternatives available	Erosion of brand pricing power
2000s onward	Anturane no longer a meaningful U.S. commercial product	Revenue and patent value effectively extinguished

The principal loss of commercial momentum came from therapeutic substitution rather than a single patent event. Allopurinol offered a more established and widely accepted approach to lowering urate production. Probenecid remained an alternative uricosuric agent, while febuxostat later provided another xanthine oxidase inhibitor option.

What is the FDA regulatory status of sulfinpyrazone?

Sulfinpyrazone has no identifiable current FDA commercial position comparable with actively marketed prescription drugs. The product is generally treated as discontinued or unavailable in the United States. It is not a current growth product in the FDA-approved gout market.

The FDA’s Drugs@FDA and Orange Book systems are the principal sources for current approved-product, application, exclusivity, and patent information.[2][3] Sulfinpyrazone does not present a current Orange Book strategy involving listed patents, pediatric exclusivity, new chemical entity exclusivity, or an active branded product facing generic entry.

What is the Orange Book status of sulfinpyrazone?

No commercially relevant current Orange Book protection has been identified for sulfinpyrazone. The practical implications are:

• No active new chemical entity exclusivity.
• No current pediatric exclusivity.
• No meaningful unexpired listed patent estate tied to a marketed U.S. reference product.
• No current branded product with material Paragraph IV exposure.
• No apparent U.S. reference-listed-drug strategy supporting a near-term generic launch event.

The absence of an active listed patent position does not prove that every historical patent has expired or that no jurisdiction contains a legacy right. It does mean that Orange Book litigation and regulatory exclusivity are not meaningful drivers of the present sulfinpyrazone market.

What patents protect sulfinpyrazone today?

No active, commercially relevant U.S. patent estate protecting sulfinpyrazone has been identified in the public regulatory record. The molecule’s age makes surviving basic compound patents highly unlikely. Any potential patent value would have to come from a later formulation, manufacturing process, dosage regimen, or specific therapeutic use.

Formulation patents

Sulfinpyrazone was historically supplied as conventional oral tablets. Conventional tablets generally provide limited patent differentiation once the active ingredient is old and generic manufacturing is straightforward. No widely recognized current extended-release, abuse-deterrent, injectable, nanoparticle, or other advanced delivery platform is associated with sulfinpyrazone.

A new formulation could theoretically create a separate patent position, but no commercially significant current formulation program is apparent from public regulatory and market records.

Method-of-use patents

Historical interest in antiplatelet activity created potential method-of-use differentiation. That opportunity did not result in a current enforceable commercial franchise. Any historical use patents covering cardiovascular prevention or thrombosis would be expected to have expired.

Current gout treatment guidelines do not identify sulfinpyrazone as a central modern therapy, which limits the commercial utility of any legacy method-of-use position.[1]

Manufacturing and intellectual-property barriers

Manufacturing barriers are low. Sulfinpyrazone is a small molecule administered orally, with no biologic manufacturing process, cell line, device platform, or complex sterile production requirement. A manufacturer would primarily need:

• Qualified active pharmaceutical ingredient supply.
• Validated tablet manufacturing.
• Stability and quality data.
• Regulatory authorization in the target jurisdiction.
• Sufficient demand to justify production.

The main barriers are market size and regulatory economics, not proprietary technology.

Which companies are challenging sulfinpyrazone patents?

No current Paragraph IV challenger landscape has been identified. Sulfinpyrazone has no active branded U.S. franchise that would normally generate Abbreviated New Drug Application litigation.

Historical generic competition likely occurred through ordinary market entry after patent expiry, but there is no current high-value patent dispute involving sulfinpyrazone comparable with litigation around modern specialty drugs.

What patent litigation affects sulfinpyrazone?

No material active U.S. patent litigation has been identified. The absence of litigation reflects the product’s commercial obsolescence and the lack of a valuable unexpired patent estate.

There is also no identified current settlement agreement involving a branded sulfinpyrazone product and a generic challenger. Reverse-payment, authorized-generic, and delayed-entry settlement structures are therefore not relevant to the present market.

How does sulfinpyrazone compare with competing gout drugs?

Sulfinpyrazone competes mainly on mechanism and historical price, not on clinical differentiation or commercial investment.

Drug	Mechanism	Current market position	Competitive effect on sulfinpyrazone
Allopurinol	Xanthine oxidase inhibitor	Standard first-line urate-lowering therapy	Strong substitution pressure
Febuxostat	Xanthine oxidase inhibitor	Established alternative, particularly for some allopurinol-intolerant patients	Reduces need for older uricosurics
Probenecid	Uricosuric	Older alternative for selected patients	Direct mechanistic competitor
Pegloticase	Recombinant uricase	Refractory chronic gout	Relevant only in severe disease
Lesinurad	Uric acid reabsorption inhibitor	Limited and withdrawn in some markets	Demonstrates difficulty sustaining newer uricosuric franchises
Sulfinpyrazone	Uricosuric	Legacy or unavailable product	Minimal current share

Allopurinol’s guideline position is the most important competitive factor. Febuxostat added another oral urate-lowering option. Probenecid remains the closest established mechanistic comparator, but its use is also narrower than that of allopurinol.

What is the financial trajectory of sulfinpyrazone?

Sulfinpyrazone’s financial trajectory is best described as originator launch, mature-product erosion, generic substitution, and commercial exit. Public company filings do not generally report sulfinpyrazone revenue as a separate product line, so reliable annual sales figures and current revenue forecasts are unavailable.

Historical revenue phases

Originator growth

Anturane benefited from being an established branded treatment for gout at a time when the therapeutic market had fewer alternatives. Revenue was driven by chronic use and physician familiarity.

Mature-product decline

The product lost differentiation as allopurinol became the dominant long-term urate-lowering treatment. Generic availability and low-cost alternatives reduced pricing power. The cardiovascular positioning of sulfinpyrazone did not create a durable second franchise.

Commercial exit

Once the originator withdrew or discontinued active commercialization, the value of the brand, sales force, and associated market infrastructure declined sharply. Any residual demand became too small or fragmented to support conventional branded promotion.

Financial driver	Direction	Effect
Brand competition	Negative	Lowered price and prescription share
Allopurinol adoption	Negative	Reduced chronic-use demand
Generic substitution	Negative	Compressed gross margin
Cardiovascular indication opportunity	Negative or neutral	Failed to sustain a large second market
Manufacturing complexity	Positive	Low production complexity
Current patient demand	Negative	Limits commercial viability
Patent protection	Negative	No current pricing moat

The product’s low manufacturing complexity could support low-cost supply, but low cost alone does not create an attractive market when prescription volume is small and regulatory maintenance costs remain.

What generic launch risks exist for sulfinpyrazone?

Generic launch risk is low from an innovator perspective because there is no meaningful originator franchise to defend. For a potential generic manufacturer, the risk is different: demand may be too limited to support a sustainable product.

Potential generic economics

A manufacturer considering sulfinpyrazone would face:

• Small and uncertain addressable demand.
• Limited physician familiarity.
• Substitution by established alternatives.
• Possible difficulty obtaining commercial-scale active ingredient.
• Low reimbursement potential.
• Regulatory maintenance costs disproportionate to sales.
• Inventory and discontinuation risk.

The product could have niche value if a country has persistent demand, limited access to alternatives, or a specialized prescribing tradition. That would be an opportunistic market rather than a high-growth pharmaceutical opportunity.

Is sulfinpyrazone a biosimilar or complex generic risk?

Sulfinpyrazone is not a biologic and has no biosimilar pathway. It is a conventional small-molecule drug. Any modern generic development would generally fall under a conventional generic framework, subject to the requirements of the target regulator.

The technical risk is lower than for biologics, depot injections, inhaled products, or complex oral delivery systems. The commercial risk is higher because the product lacks a strong current market and has substantial therapeutic substitution.

What geographic markets still have potential for sulfinpyrazone?

Any residual opportunity is likely jurisdiction-specific. A product with little or no U.S. value could still have limited demand in markets where:

• Sulfinpyrazone remains recognized in local formularies.
• Generic alternatives are unavailable or expensive.
• Physicians continue to use older uricosurics.
• A local manufacturer can produce at low marginal cost.
• Regulatory re-registration is inexpensive.

No evidence supports a broad multinational relaunch. The strongest commercial case would be a low-cost, tightly targeted product in a jurisdiction with documented demand. Western developed markets are unlikely to support meaningful brand investment.

How strong is the sulfinpyrazone patent estate?

The current patent estate is weak to nonexistent from a commercial perspective.

Estate component	Current assessment
Composition-of-matter protection	Expired or commercially irrelevant
Formulation protection	No material active estate identified
Method-of-use protection	Historical and expired
Manufacturing protection	No meaningful barrier identified
Orange Book patents	No current commercially relevant listing identified
Litigation leverage	Negligible
Licensing value	Limited to legacy rights or local supply arrangements

The absence of meaningful patent protection prevents premium pricing and makes a relaunch dependent on regulatory execution, supply reliability, and local demand.

What licensing deals involve sulfinpyrazone?

No current material licensing transaction involving sulfinpyrazone has been identified. The historical product was associated with Geigy and the later Ciba-Geigy corporate structure, but current licensing value is unlikely to be significant.

A potential transaction would more likely involve:

• A regional distribution agreement.
• A dormant trademark or legacy product transfer.
• A local manufacturing authorization.
• A regulatory-file transfer.
• A small-volume supply contract.

A conventional global pharmaceutical license would be difficult to justify without evidence of substantial prescription volume.

Key Takeaways

• Sulfinpyrazone is a legacy uricosuric drug with no meaningful current U.S. commercial franchise.
• Anturane’s commercial decline resulted from therapeutic substitution, generic erosion, and loss of clinical differentiation.
• No current Orange Book exclusivity, relevant listed patent, Paragraph IV dispute, or material patent litigation has been identified.
• Composition, formulation, and method-of-use patent value is effectively exhausted.
• Sulfinpyrazone has no biosimilar exposure because it is a conventional small molecule.
• The main commercial competitors are allopurinol, febuxostat, and probenecid.
• Current revenue is not separately reported and is unlikely to be material for major pharmaceutical companies.
• Any remaining opportunity is regional and niche, with market demand rather than intellectual property as the central risk.

FAQs

Can sulfinpyrazone still be prescribed in the United States?

It is not a meaningful current U.S. commercial product. Availability may depend on specific regulatory, pharmacy, or compounding circumstances, but it does not have the market position of approved first-line gout therapies.

Why did sulfinpyrazone lose to allopurinol?

Allopurinol became the preferred long-term urate-lowering therapy for many patients because it reduces uric acid production and gained broader guideline and prescriber acceptance. Sulfinpyrazone’s uricosuric mechanism was less suitable for some patients and offered limited modern differentiation.

Does sulfinpyrazone have an active compound patent?

No commercially relevant active compound patent has been identified. The molecule is sufficiently old that any original composition protection would have expired.

Could a generic company relaunch sulfinpyrazone?

A relaunch is technically possible in a jurisdiction that accepts a new generic application, but the business case would depend on local demand, regulatory cost, active-ingredient supply, and reimbursement. The principal risk is insufficient volume.

Is sulfinpyrazone relevant to pharmaceutical investors?

It is relevant mainly as a legacy-drug case study. It does not present the characteristics of an investable protected asset: there is no clear exclusivity runway, no active litigation catalyst, no reported revenue growth, and no strong formulation moat.

References

1. FitzGerald, J. D., Dalbeth, N., Mikuls, T., Brignardello-Petersen, R., Guyatt, G., Abeles, A. M., Khanna, D., King, C., Levy, G., Libbey, C., Mount, D., Pillinger, M. H., Rosenthal, A., Singh, J. A., Sims, J. E., Smith, B. J., Wenger, N. S., & Neogi, T. (2020). 2020 American College of Rheumatology guideline for the management of gout. Arthritis Care & Research, 72(6), 744-760.

2. U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/

3. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book

4. National Library of Medicine. (n.d.). Sulfinpyrazone. PubChem. https://pubchem.ncbi.nlm.nih.gov/compound/Sulfinpyrazone

5. National Library of Medicine. (n.d.). Sulfinpyrazone drug information. DailyMed. https://dailymed.nlm.nih.gov/દailyMed/