When will the PROBALAN patents expire, and when will generic PROBALAN be available?

Sponsor	Phase
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)	Early Phase 1
Washington State University	Early Phase 1
National Institutes of Health (NIH)	Early Phase 1

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Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Lannett	PROBALAN	probenecid	TABLET;ORAL	080966-001	Approved Prior to Jan 1, 1982	AB	RX	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Exclusivity Expiration

Last updated: November 13, 2026

Probalan is a branded oral formulation of probenecid, an established uricosuric drug used primarily to reduce serum uric acid in gout and hyperuricemia. Its commercial position is weak relative to newer gout therapies because probenecid is an old, off-patent active ingredient with multiple generic suppliers, limited pricing power, and low prescription growth.

No public company reports standalone Probalan revenue. The financial profile is therefore best assessed through product status, generic competition, market access, supply conditions, and the economics of low-volume generic drugs rather than through a separately disclosed sales forecast.

What is Probalan and how is it used?

Probalan contains probenecid, generally supplied as a 500 mg oral tablet. Probenecid increases renal uric acid excretion by inhibiting tubular reabsorption. It is used for chronic gout management and may be used with certain antibiotics to reduce renal clearance, although the gout indication is the principal commercial use.

Attribute	Probalan
Active ingredient	Probenecid
Drug class	Uricosuric agent
Common strength	500 mg tablet
Primary indication	Chronic gout and hyperuricemia
Route	Oral
FDA status	Prescription drug
Reference product status	Legacy product with generic competition
Biosimilar exposure	None
Principal competitors	Generic probenecid tablets, allopurinol, febuxostat, pegloticase and other gout therapies
Commercial position	Mature, low-growth, genericized product

Probenecid is generally used when urate overproduction is not the dominant problem and renal function is adequate. It is less attractive for many patients than xanthine oxidase inhibitors because of dosing frequency, kidney-related restrictions, drug interactions, and the need for adequate hydration.

What is the FDA regulatory status of Probalan?

Probalan is regulated as a prescription drug, not as a biologic. FDA regulatory value is limited because the active ingredient has been approved for decades and generic probenecid products are available.

The FDA’s Drugs@FDA and Orange Book databases are the primary sources for determining whether a specific Probalan application remains approved, marketed, or listed as discontinued. Product-level commercial status can change independently from the underlying approval. A sponsor may stop marketing a brand while generic probenecid remains available.

The key regulatory distinctions are:

Probalan’s active ingredient is not protected by modern chemical patent exclusivity.
Generic applicants can generally rely on an abbreviated new drug application pathway.
Any remaining commercial differentiation would arise from supply reliability, branding, packaging, distribution, or contractual channels.
The product does not have biosimilar competition because probenecid is a small-molecule drug.

FDA listings should be reviewed at the National Drug Code and application level because “discontinued” can describe a marketed presentation rather than withdrawal for safety or efficacy reasons. [1][2]

When does Probalan lose exclusivity?

Probalan’s core market exclusivity has already expired. Probenecid was introduced long before the modern Hatch-Waxman patent system, and the commercially relevant compound and tablet formulation are now genericized.

Exclusivity category	Probalan status
New chemical entity exclusivity	Expired
Core compound patent protection	Expired
Standard formulation patent protection	No meaningful current barrier identified
Orphan-drug exclusivity	Not applicable to the legacy product
Pediatric exclusivity	No current commercial relevance
Biosimilar exclusivity	Not applicable
Generic substitution risk	High

A new patent could theoretically cover a novel formulation, dosing regimen, combination, or manufacturing process. Such a patent would not restore broad exclusivity to conventional 500 mg probenecid tablets. The commercial value of any narrow patent would depend on FDA approval, Orange Book listing eligibility, claim scope, and whether the patented feature is required for the labeled product.

What patents protect Probalan?

No current, broad patent estate is publicly associated with conventional Probalan 500 mg tablets that would materially block generic probenecid tablets.

The relevant IP position is primarily negative:

The probenecid active ingredient is old.
Generic manufacturers can produce conventional tablets without relying on a recent Probalan patent.
Any historical patents covering probenecid, its synthesis, or early pharmaceutical compositions have expired.
Method-of-use patents would have limited value unless they covered a commercially important, FDA-approved indication and could be listed or enforced effectively.
Manufacturing patents could affect a particular supplier but would not normally prevent other manufacturers from producing probenecid through an alternative process.

Are there formulation patents for Probalan?

There is no widely recognized, commercially significant formulation patent barrier for standard Probalan tablets. A sustained-release, fixed-dose combination, or novel delivery system could create new patent value, but conventional immediate-release probenecid tablets remain exposed to generic competition.

Are there Paragraph IV challenges to Probalan?

Paragraph IV litigation is unlikely to be a material current market issue for Probalan because the core product is old and generic probenecid approvals have existed for many years. Paragraph IV certifications are most relevant when an ANDA applicant challenges an unexpired listed patent. A conventional probenecid tablet does not present the type of active, high-value Orange Book patent dispute associated with newer branded drugs.

How large is the Probalan market?

Standalone Probalan sales are not publicly disclosed. The brand competes in a small segment of the broader gout market, where the leading pharmacologic alternatives are allopurinol and febuxostat.

The market structure is shaped by four factors:

Generic price pressure

Probenecid is a mature generic drug. Retail prices can vary substantially by pharmacy, payer, package size, and manufacturer, but the product generally lacks the pricing power of branded specialty medicines. Gross revenue can increase temporarily during shortages, supplier exits, or contract repricing, but these effects are difficult to sustain.

Limited clinical growth

Probenecid has a narrower eligible patient population than allopurinol. Guidelines commonly position allopurinol as the preferred first-line urate-lowering therapy, including in many patients with chronic kidney disease. Probenecid is less suitable when kidney function is reduced and may be avoided in patients with a history of uric acid nephrolithiasis.

Substitution by competing therapies

The main therapeutic competitors are:

Therapy	Commercial impact on probenecid
Allopurinol	Strongest substitute; inexpensive and widely used
Febuxostat	Substitute for patients unable to use or tolerate allopurinol
Pegloticase	Specialty option for refractory chronic gout
Colchicine	Manages flares but does not replace long-term urate lowering
Lesinurad	Historical uricosuric competitor; commercial availability has declined
Generic probenecid	Direct substitute for Probalan

Allopurinol has the largest competitive effect because it is inexpensive, widely recognized, and generally preferred for long-term urate lowering. Febuxostat competes in patients with allopurinol intolerance or inadequate response.

Low-volume generic economics

A product such as probenecid can remain commercially available despite modest demand because manufacturing costs may be manageable and the product can be included in a supplier’s broader generic portfolio. The commercial weakness is that low demand can also make the product vulnerable to:

Manufacturing-line prioritization for higher-volume products.
API supply interruptions.
Contract manufacturer exits.
Product discontinuation when margins fall below portfolio thresholds.
Pharmacy substitution toward another generic supplier.

What is the financial trajectory for Probalan?

The expected financial trajectory is mature-to-declining, with episodic volatility rather than durable growth.

Period	Expected commercial pattern
Historical period	Brand-led sales before broad generic penetration
Generic expansion	Rapid price erosion and loss of branded share
Current mature phase	Low revenue, limited volume growth, supplier-driven pricing
Short-term upside case	Temporary revenue increase from shortages or competitor exits
Base case	Flat to declining nominal sales
Downside case	Brand withdrawal or loss of distribution
Long-term case	Continued availability through generic probenecid, with limited branded value

The brand’s economics depend less on market expansion than on whether the sponsor maintains distribution and whether Probalan has a premium over generic probenecid. If payers and pharmacies treat the product as therapeutically interchangeable with generic tablets, the brand premium will be difficult to defend.

Publicly available company filings do not identify a separate Probalan revenue line. Any valuation should therefore avoid assigning a branded-drug multiple to the product. A more appropriate framework is:

Estimate prescription volume.
Apply realized net price after payer discounts.
Separate branded Probalan volume from generic probenecid volume.
Deduct distribution, manufacturing, quality, and regulatory costs.
Model probability of continued marketing.
Add a temporary shortage premium only under a defined supply-disruption scenario.

Which companies compete with Probalan?

Competition is divided between branded or legacy suppliers and generic manufacturers. Supplier rosters may change because FDA-approved manufacturers can discontinue a product, transfer an application, or alter their National Drug Code listings.

The competitive set includes:

Generic probenecid tablet manufacturers.
Contract manufacturers supplying private-label pharmacy products.
Allopurinol manufacturers.
Febuxostat manufacturers.
Specialty-gout companies selling advanced therapies such as pegloticase.

Generic competition is more important than direct branded competition. Even if Probalan has strong physician recognition, pharmacy-level substitution can redirect demand to lower-cost probenecid products.

What generic entry risks exist for Probalan?

Generic entry risk is already realized rather than prospective. The principal risk is not a future first generic launch. It is continued erosion of branded demand and the possibility that generic suppliers gain greater formulary and wholesaler penetration.

Generic launch scenarios

Base case

Generic probenecid remains available from several suppliers. Probalan maintains a small branded niche but experiences flat or declining unit volume and limited pricing power.

Supply-disruption case

One or more generic manufacturers exit or experience production problems. Probalan may gain temporary volume, particularly if wholesalers seek a reliable alternative. The effect would likely be constrained by the size of the probenecid market.

Brand-withdrawal case

The sponsor stops marketing Probalan. Patients and pharmacies transition to generic probenecid, assuming adequate supply. The underlying molecule remains commercially available even if the brand disappears.

Reformulation case

A sponsor introduces a differentiated formulation or combination product. This could create new commercial value, but it would require clinical, regulatory, manufacturing, and patent investment. It would not automatically improve the economics of standard Probalan tablets.

What manufacturing and supply barriers affect Probalan?

Probenecid does not have the manufacturing complexity of a biologic, sterile injectable, or highly potent oncology drug. The main barriers are operational:

Reliable active pharmaceutical ingredient supply.
Validation of tablet manufacturing.
Quality-control testing.
Stability and packaging compliance.
FDA establishment compliance.
Commercial justification for maintaining a low-volume product line.

These barriers can still matter because low-volume drugs are vulnerable to supply concentration. If only a small number of manufacturers remain active, a single plant closure or API disruption can affect availability.

The absence of manufacturing complexity limits long-term defensibility. A competitor with an approved product and reliable supply can generally enter or expand without solving a difficult delivery-technology problem.

How does Probalan compare with allopurinol and febuxostat?

Factor	Probalan	Allopurinol	Febuxostat
Mechanism	Increases uric acid excretion	Reduces uric acid production	Reduces uric acid production
Generic availability	Yes	Yes	Yes
Typical market position	Alternative uricosuric	First-line standard for many patients	Alternative when allopurinol is unsuitable
Kidney limitations	Important	Dose adjustment often required	Used with renal considerations
Commercial growth	Low	Larger and more stable	Moderate niche demand
Patent protection	Expired	Expired	Core protection expired in major markets
Pricing power	Low	Low	Low to moderate depending on product
Main advantage	Mechanistically distinct option	Broad clinical use and low cost	Alternative xanthine oxidase inhibitor

Probalan has a narrower commercial role than both major xanthine oxidase inhibitors. Its value is mainly as an established alternative for selected patients, not as a growth product.

What is the geographic coverage of Probalan?

Probenecid is available in multiple markets as a generic medicine, but brand names, approved strengths, suppliers, and reimbursement conditions vary by country. Probalan’s commercial value is therefore jurisdiction-specific.

In the United States, the principal issues are FDA approval status, Orange Book and NDC records, pharmacy substitution, wholesaler access, and generic supply. In other jurisdictions, the product may be sold under different brand names or only as a generic.

International expansion would face limited upside because probenecid is already old, inexpensive, and widely substitutable. The main opportunity would be distribution into markets with a constrained supplier base, but that opportunity would be operational rather than patent-driven.

What is the litigation and settlement outlook for Probalan?

There is no obvious current high-value patent litigation landscape comparable to newer branded medicines. The likely legal issues are commercial and regulatory:

Product liability.
Manufacturing compliance.
Labeling and promotional claims.
Supply and distribution contracts.
Generic approval or marketing disputes.
Trademark rights associated with the Probalan name.

Paragraph IV settlements, authorized-generic strategies, and launch-at-risk litigation are unlikely to drive the product’s current valuation because broad exclusivity has already expired.

Key Takeaways

Probalan is a legacy probenecid product with limited standalone commercial value.
The active ingredient and conventional tablet formulation are effectively genericized.
No current broad patent barrier is expected to protect standard Probalan tablets.
Probalan has no biosimilar risk because it is a small-molecule drug.
Allopurinol and febuxostat limit clinical and commercial growth.
Public companies do not generally disclose standalone Probalan revenue.
The base financial outlook is flat to declining, with temporary upside possible during generic shortages.
The most important value drivers are supply reliability, distribution, payer substitution, and continued marketing.
A novel formulation or combination could create new IP value, but standard Probalan does not have a meaningful growth platform.

FAQs

Is Probalan still commercially available?

Availability depends on the specific market, National Drug Code, manufacturer, and pharmacy inventory. Generic probenecid is the more durable source of supply.

Is Probalan the same as generic probenecid?

Yes. Probalan and generic probenecid contain the same active ingredient, although inactive ingredients, packaging, manufacturer, and price may differ.

Can a generic manufacturer challenge Probalan with a Paragraph IV filing?

A Paragraph IV filing would matter only if an unexpired, listed patent covered the relevant product. Standard probenecid tablets do not present a significant current patent barrier.

Does Probalan have orphan-drug exclusivity?

No. Probalan is a legacy product and is not commercially protected by current orphan-drug exclusivity.

Could Probalan revenue rise during a drug shortage?

Yes. A shortage of generic probenecid could shift temporary demand toward an available branded product. The effect would depend on inventory, wholesaler access, payer coverage, and the duration of the shortage.

References

U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/
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
U.S. National Library of Medicine. (n.d.). DailyMed: Probenecid drug labeling. https://dailymed.nlm.nih.gov/dailymed/
FitzGerald, J. D., Dalbeth, N., Mikuls, T., Brignardello-Petersen, R., Guyatt, G., Abeles, A. M., Andrade, A. J., Andrés, M., Becker, M. A., Gaffo, A. L., et al. (2020). 2020 American College of Rheumatology guideline for the management of gout. Arthritis Care & Research, 72(6), 744-760.
U.S. Food and Drug Administration. (n.d.). National Drug Code Directory. https://www.accessdata.fda.gov/scripts/cder/ndc/

US Patents:	0
Applicants:	1
NDAs:	1
Finished Product Suppliers / Packagers:	3
Raw Ingredient (Bulk) Api Vendors:	96
Clinical Trials:	5
Patent Applications:	2,687
DailyMed Link:	PROBALAN at DailyMed

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