ANCOBON Drug Patent Profile

When do Ancobon patents expire, and what generic alternatives are available?

Ancobon is a drug marketed by Bausch and is included in one NDA.

The generic ingredient in ANCOBON is flucytosine. There are seven drug master file entries for this compound. Ten suppliers are listed for this compound. Additional details are available on the flucytosine profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Ancobon

A generic version of ANCOBON was approved as flucytosine by SIGMAPHARM LABS LLC on June 28^th, 2011.

Summary for ANCOBON

US Patents:	0
Applicants:	1
NDAs:	1
Finished Product Suppliers / Packagers:	1
Raw Ingredient (Bulk) Api Vendors:	177
Clinical Trials:	2
Patent Applications:	4,709
Drug Prices:	Drug price information for ANCOBON
What excipients (inactive ingredients) are in ANCOBON?	ANCOBON excipients list
DailyMed Link:	ANCOBON at DailyMed

See drug prices for ANCOBON

Recent Clinical Trials for ANCOBON

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

Sponsor	Phase
Yale University	Phase 2
National Institute of Neurological Disorders and Stroke (NINDS)	Phase 2
Valeant Pharmaceuticals International, Inc.	Phase 2

See all ANCOBON clinical trials

Pharmacology for ANCOBON

Drug Class

Nucleoside Analog Antifungal

US Patents and Regulatory Information for ANCOBON

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Bausch	ANCOBON	flucytosine	CAPSULE;ORAL	017001-001	Approved Prior to Jan 1, 1982	AB	RX	Yes	No
Bausch	ANCOBON	flucytosine	CAPSULE;ORAL	017001-002	Approved Prior to Jan 1, 1982	AB	RX	Yes	Yes

ANCOBON Market Dynamics, Patent Status, and Financial Trajectory

Last updated: August 10, 2026

ANCOBON is the former U.S. brand for flucytosine, an oral antifungal used mainly with amphotericin B for cryptococcal meningitis and selected serious Candida infections. Its commercial history is defined by low patient volume, high clinical importance, limited manufacturing capacity, and unusually high branded pricing rather than by patent exclusivity. The U.S. brand has been discontinued, while flucytosine remains an important essential medicine supplied through generic and international channels.

No standalone ANCOBON revenue series is publicly reported. Bausch Health and its predecessors reported the product within broader pharmaceutical portfolios, preventing a reliable product-level financial reconstruction [1].

What is ANCOBON and how is flucytosine used?

ANCOBON contains flucytosine, also known as 5-fluorocytosine. It is an oral antimetabolite antifungal that is generally used in combination therapy because resistance can develop rapidly when it is administered alone.

Attribute	ANCOBON / flucytosine
Active ingredient	Flucytosine
Drug class	Antimetabolite antifungal
Former U.S. brand	ANCOBON
Dosage forms	250 mg and 500 mg capsules
Main uses	Cryptococcal meningitis; selected Candida infections
Typical role	Combination therapy, commonly with amphotericin B
U.S. regulatory application	NDA 016954
Former U.S. marketing company	Valeant Pharmaceuticals North America, later associated with Bausch Health
Current brand status	U.S. brand discontinued
Patent position	No meaningful active U.S. composition-of-matter estate

Flucytosine has favorable penetration into cerebrospinal fluid, which makes it clinically valuable in cryptococcal meningitis. Its use is constrained by bone-marrow suppression, gastrointestinal toxicity, renal dosing requirements, and the need for laboratory monitoring [2].

What is the FDA status of ANCOBON?

The FDA lists ANCOBON as a discontinued product. The discontinuation reflects commercial marketing status, not an FDA determination that flucytosine is unsafe or ineffective [3].

The underlying active ingredient remains recognized in clinical guidelines and global essential-medicine frameworks. The FDA approval of the original product dates to the era before modern pharmaceutical exclusivity systems. ANCOBON therefore does not have a current period of FDA new-drug exclusivity comparable to a recently approved specialty drug.

ANCOBON regulatory timeline

Period	Event
1970s	U.S. approval and commercialization of oral flucytosine
1980s-2000s	Use established in combination treatment for cryptococcal meningitis and serious Candida disease
2010s	Sharp public attention to U.S. pricing and supply limitations
Mid-to-late 2010s	U.S. ANCOBON marketing discontinued
Subsequent period	Generic and non-U.S. supply channels remained relevant
Current position	Flucytosine remains clinically used, but the ANCOBON brand is not a major active U.S. commercial franchise

What patents protect ANCOBON and flucytosine?

No active U.S. patent estate materially protects ANCOBON or the flucytosine molecule. The compound was discovered and commercialized many decades ago, so any original composition-of-matter protection expired long before the current market period.

The FDA Orange Book does not provide a current patent barrier that would delay generic flucytosine entry [4]. The commercial risks around the product have therefore been supply, manufacturing, regulatory compliance, and procurement economics rather than patent litigation.

Patent category	ANCOBON position
Composition-of-matter patent	Expired
Basic formulation patent	No current material barrier identified
Method-of-use patent	No meaningful Orange Book exclusivity barrier
Pediatric exclusivity	None relevant to the current brand
Orphan exclusivity	No current enforceable exclusivity identified
Orange Book patent litigation	No significant current Paragraph IV dispute identified

What formulations are protected by ANCOBON patents?

The original capsule formulation does not have a commercially meaningful surviving patent position. Generic manufacturers can pursue abbreviated approval or other applicable regulatory pathways without confronting an active brand patent listed for the product.

Any practical formulation advantage would be based on manufacturing controls, bioequivalence, stability, supply reliability, or distribution arrangements. Those factors are commercial barriers, not patent exclusivity.

When did ANCOBON lose exclusivity?

ANCOBON lost effective market exclusivity long before its U.S. brand discontinuation. The brand's later pricing power did not come from a live patent monopoly. It came from a concentrated market with few suppliers, low demand, difficult inventory economics, and the clinical importance of having an oral flucytosine source available.

This distinction matters for generic-entry analysis. A competitor did not need to overcome a current composition-of-matter patent. It needed to secure a dependable active-pharmaceutical-ingredient supply, complete FDA requirements, and operate profitably in a small market.

Why did ANCOBON command high prices despite expired patents?

Flucytosine illustrates how a drug can become expensive without active patent protection.

The U.S. market has several structural constraints:

1. Patient volume is low compared with common anti-infective therapies.
2. Treatment is concentrated in specialized hospitals and infectious-disease centers.
3. The drug requires renal-function monitoring and toxicity management.
4. Demand is difficult to forecast because cryptococcal meningitis is relatively uncommon in the United States.
5. Manufacturers face inventory and quality-control costs for a product with limited annual volume.
6. Hospitals and payers often need immediate access because treatment delays can be clinically serious.

Reports in the mid-2010s described U.S. treatment costs that could reach tens of thousands of dollars for a course of therapy, while prices in some other countries were materially lower [5]. Those comparisons reflected market structure and purchasing arrangements as much as manufacturing cost.

The pricing model was vulnerable because it depended on a narrow installed base of prescribers and limited substitution. Once generic supply became available, the commercial rationale for maintaining a premium brand weakened.

How strong is the ANCOBON patent estate?

The patent estate is weak to nonexistent as a current exclusivity asset. The product's value was based on clinical utility and supply scarcity, not intellectual-property protection.

Patent-strength assessment

Factor	Assessment
Molecule protection	Very weak; historical protection expired
Formulation protection	Weak
Method-of-use protection	Weak
Manufacturing know-how	Potentially relevant, but not a listed patent moat
Regulatory exclusivity	None of current commercial significance
Litigation leverage	Low
Generic vulnerability	High once reliable supply is established

For licensing or acquisition purposes, ANCOBON would not qualify as a conventional patent-protected specialty asset. Any value would lie in distribution, hospital contracting, manufacturing know-how, or supply continuity.

Which companies challenged ANCOBON's market position?

The principal competitive threat came from generic flucytosine suppliers rather than from Paragraph IV litigation. Publicly visible competition has included generic and international suppliers, but the market has not developed the broad supplier base seen in large-volume oral antibiotics.

The relevant competitive question is whether a supplier can maintain consistent U.S.-compliant production. A nominally approved generic does not eliminate shortage risk if the manufacturer faces API constraints, quality issues, or insufficient commercial volume.

Are there Paragraph IV challenges to ANCOBON?

No major current Paragraph IV campaign is associated with ANCOBON's commercial position. The reason is straightforward: there is no significant active patent portfolio to challenge.

Generic entry therefore follows the economics of abbreviated approval, manufacturing capability, and procurement rather than patent-certification litigation. This materially reduces legal costs but does not eliminate operational barriers.

What is the Orange Book status of ANCOBON?

The Orange Book is relevant for identifying approved products and listed patents. ANCOBON's current commercial position does not depend on an Orange Book patent listing. The product is listed as discontinued in FDA databases, while flucytosine itself remains an approved therapeutic ingredient through applicable products and regulatory pathways [3][4].

A discontinued brand can still matter commercially if physicians recognize it, hospitals retain historical purchasing protocols, or a manufacturer controls residual distribution rights. Those factors do not restore exclusivity.

What patent litigation affects ANCOBON?

No material current U.S. patent litigation is known to affect ANCOBON. The absence of litigation is consistent with the product's age and the lack of a live Orange Book patent barrier.

The principal legal and commercial exposure has instead involved:

• Product discontinuation and supply continuity
• Generic approval and manufacturing compliance
• Contracting with hospitals and specialty distributors
• Pricing scrutiny
• Potential antitrust or market-access concerns in a concentrated supply market

There is no biosimilar pathway for flucytosine because it is a small-molecule drug, not a biologic. Biosimilar risk is therefore not applicable. Generic substitution is the relevant competitive mechanism.

What is the financial trajectory of ANCOBON?

ANCOBON's financial trajectory can be divided into four phases.

Early branded commercialization

The product entered a mature anti-infective market with limited volume. Revenue was likely modest in absolute terms because the addressable patient population was narrow.

Portfolio ownership and price escalation

After ownership changes associated with Valeant, ANCOBON became a frequently cited example of high pricing for an old hospital drug. Price increases created a larger revenue opportunity per treatment course but also increased payer scrutiny and political exposure [5].

Brand discontinuation

The U.S. brand was discontinued after the commercial model became difficult to sustain. Discontinuation did not remove clinical demand for flucytosine. It shifted demand toward generic and international sources.

Generic and supply-constrained market

Generic entry reduced the defensibility of branded pricing. However, a small supplier base and limited production capacity continued to support a premium relative to manufacturing cost in some procurement channels.

Because company filings do not disclose ANCOBON revenue separately, precise annual sales, gross margin, EBITDA contribution, and product-level price-volume decomposition cannot be established from public filings [1]. The appropriate financial conclusion is that ANCOBON was strategically important in selected infectious-disease settings but unlikely to have been a material group-level revenue driver for a company the size of Valeant or Bausch Health.

What generic entry risks exist for ANCOBON?

The brand faces high generic substitution risk, but generic entry does not guarantee a fully competitive market.

Risk	Effect on ANCOBON economics
Generic capsule approval	Eliminates practical brand pricing power
Hospital formulary substitution	Accelerates volume migration
International procurement	Increases price transparency
API disruption	Can preserve scarcity premiums
Quality or shortage events	May temporarily restore demand for alternate suppliers
Clinical preference for reliable supply	Supports incumbent vendors
Small patient population	Limits the number of economically viable manufacturers

A generic launch can reduce price while leaving the market exposed to shortages. This creates a two-tier outcome: lower long-run brand value, but episodic pricing power for suppliers with dependable inventory.

How does ANCOBON compare with competing antifungal therapies?

Flucytosine is not a broad substitute for modern antifungal agents. It occupies a specialized role in combination regimens.

Therapy	Primary advantage	Main limitation relative to flucytosine
Flucytosine	Oral administration and strong CNS penetration	Cytopenias, gastrointestinal toxicity, monitoring burden
Amphotericin B	Potent fungicidal activity	Intravenous administration and renal toxicity
Fluconazole	Oral, widely available, lower cost	May be inadequate as sole initial therapy for severe disease
Isavuconazole or voriconazole	Broader modern antifungal utility	Different indications, interactions, and cost structures

For cryptococcal meningitis, treatment guidelines have historically placed amphotericin B plus flucytosine among preferred induction strategies in appropriate patients [2]. This clinical role limits the ability of physicians to eliminate flucytosine solely through price substitution.

What licensing deals affect ANCOBON?

No major current licensing transaction has established a visible standalone ANCOBON franchise. Historical ownership through Valeant and related corporate entities was more important than a technology license.

Any current transaction involving flucytosine would likely focus on:

• U.S. generic marketing rights
• Hospital distribution
• API sourcing
• Contract manufacturing
• Shortage-management supply agreements
• International access programs

A license supported only by the ANCOBON trademark would have limited strategic value. A supply-controlled arrangement could have greater value because continuity is the principal market differentiator.

What geographic markets matter for flucytosine?

The United States is commercially important because historical branded prices were high, but demand is concentrated in a small number of hospitals. Europe and other developed markets generally have more established generic or public-purchasing mechanisms. Low- and middle-income countries have substantial clinical need, particularly for cryptococcal disease associated with HIV, but affordability and supply access remain significant constraints [6].

Geographic value is therefore uneven:

• United States: high historical price, low volume, supply and reimbursement sensitivity.
• Europe: lower pricing, greater generic and public-purchasing pressure.
• Sub-Saharan Africa: high medical need, major affordability and access constraints.
• Asia and Latin America: mixed regulatory access and variable generic supply.

Key Takeaways

• ANCOBON is the former U.S. brand for flucytosine.
• The U.S. brand has been discontinued, but the active ingredient remains clinically important.
• No meaningful active patent or Orange Book exclusivity barrier protects the molecule.
• Paragraph IV litigation and biosimilar risk are not material to the asset.
• Historical pricing power came from scarcity and market concentration, not patent protection.
• Generic substitution is the main long-term threat.
• Supply reliability, API access, and hospital distribution are more important than intellectual property.
• No standalone ANCOBON revenue or profit series is publicly disclosed.
• The product was strategically important in cryptococcal meningitis but unlikely to have been a material group-level revenue driver for its former corporate owners.

FAQs about ANCOBON

Is ANCOBON still available in the United States?

The ANCOBON brand is listed as discontinued. Flucytosine may remain available through generic or other approved supply channels.

Is flucytosine a generic drug?

Yes. Flucytosine is an old small-molecule drug, and generic competition is the relevant market pathway.

Does flucytosine have orphan-drug exclusivity?

No current orphan exclusivity materially protects the historical ANCOBON brand.

Can hospitals substitute fluconazole for flucytosine?

Substitution depends on the infection, disease severity, susceptibility, renal status, and treatment guidelines. Fluconazole is not a universal substitute for flucytosine in initial therapy for severe cryptococcal disease.

Is ANCOBON an attractive pharmaceutical licensing asset?

As a branded patent asset, ANCOBON is weak. A transaction could still have value if it controls dependable manufacturing, API supply, generic distribution, or hospital contracts.

References

1. Bausch Health Companies Inc. (2024). Annual report for the fiscal year ended December 31, 2023.
2. Perfect, J. R., Dismukes, W. E., Dromer, F., Goldman, D. L., Graybill, J. R., Hamill, R. J., Harrison, T. S., Larsen, R. A., Lortholary, O., Nguyen, M.-H., Pappas, P. G., & Powderly, W. G. (2010). Clinical practice guidelines for the management of cryptococcal disease: 2010 update by the Infectious Diseases Society of America. Clinical Infectious Diseases, 50(3), 291-322.
3. U.S. Food and Drug Administration. (n.d.). Drugs@FDA: ANCOBON, NDA 016954.
4. U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations, Orange Book.
5. Doctors Without Borders. (2016). Flucytosine: An essential medicine that remains inaccessible in many countries.
6. World Health Organization. (2023). WHO fungal priority pathogens list to guide research, development and public health action.