FLAGYL Drug Patent Profile

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When do Flagyl patents expire, and when can generic versions of Flagyl launch?

Flagyl is a drug marketed by Pfizer and Baxter Hlthcare and is included in five NDAs.

The generic ingredient in FLAGYL is metronidazole hydrochloride. There are two drug master file entries for this compound. Additional details are available on the metronidazole hydrochloride profile page.

Summary for FLAGYL

US Patents:	0
Applicants:	2
NDAs:	5
Finished Product Suppliers / Packagers:	1
Raw Ingredient (Bulk) Api Vendors:	1
Clinical Trials:	77
Patent Applications:	4,018
Drug Prices:	Drug price information for FLAGYL
What excipients (inactive ingredients) are in FLAGYL?	FLAGYL excipients list
DailyMed Link:	FLAGYL at DailyMed

See drug prices for FLAGYL

See drug sales revenues for FLAGYL

Recent Clinical Trials for FLAGYL

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

Sponsor	Phase
Medical College of Wisconsin	EARLY_PHASE1
Gateway Pharmaceutical LLC	PHASE1
Hayder Adnan Fawzi	PHASE2

See all FLAGYL clinical trials

Pharmacology for FLAGYL

Drug Class

Nitroimidazole Antimicrobial

US Patents and Regulatory Information for FLAGYL

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Pfizer	FLAGYL	metronidazole	CAPSULE;ORAL	020334-001	May 3, 1995	AB	RX	Yes	Yes
Pfizer	FLAGYL I.V. RTU IN PLASTIC CONTAINER	metronidazole	INJECTABLE;INJECTION	018353-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Pfizer	FLAGYL ER	metronidazole	TABLET, EXTENDED RELEASE;ORAL	020868-001	Nov 26, 1997		DISCN	Yes	No
Pfizer	FLAGYL	metronidazole	TABLET;ORAL	012623-001	Approved Prior to Jan 1, 1982		DISCN	Yes	No
Pfizer	FLAGYL	metronidazole	TABLET;ORAL	012623-003	Approved Prior to Jan 1, 1982		DISCN	Yes	No

Flagyl (Metronidazole) Market Dynamics, Patent Status, and Financial Trajectory

Last updated: October 4, 2026

Flagyl is the original branded formulation of metronidazole, a mature nitroimidazole antimicrobial. Its commercial trajectory is defined by generic substitution, low unit pricing, broad supplier competition, and limited brand-level disclosure. The active ingredient has been off-patent for decades, and Flagyl no longer has the exclusivity profile of a protected pharmaceutical asset. Current value is concentrated in high-volume generic metronidazole products, hospital supply contracts, and selected formulations rather than in the legacy brand.

What is Flagyl and how large is the metronidazole market?

Flagyl contains metronidazole, an antimicrobial used against anaerobic bacteria and certain protozoal infections. FDA-approved dosage forms and related metronidazole products include oral tablets, intravenous injection, vaginal gel, topical formulations, and compounded or locally marketed preparations.[1]

The core market has several demand segments:

Segment	Principal use	Competitive structure
Oral metronidazole	Anaerobic infections, trichomoniasis, amebiasis, giardiasis, bacterial vaginosis	Highly competitive generic market
Intravenous metronidazole	Hospital and surgical infections	Generic suppliers and institutional contracts
Vaginal gel	Bacterial vaginosis	Generic products and branded alternatives
Topical gel or cream	Rosacea and other dermatologic indications	Generic metronidazole and specialty dermatology brands
Veterinary products	Anaerobic and protozoal infections	Separate animal-health market

Flagyl’s branded demand is small relative to total metronidazole demand. Prescribers generally use the nonproprietary name, and pharmacies commonly dispense generic metronidazole unless a payer, physician, or patient specifically requests the branded product.

How has Flagyl’s financial trajectory changed?

Flagyl’s financial trajectory follows the standard pattern for an originator antimicrobial:

1. Premium branded sales during the protected period.
2. Rapid price erosion after generic entry.
3. Long-term persistence as a recognized brand with declining strategic importance.
4. Low-margin residual sales, licensing, or supply activity.
5. Economic value shifting from the brand owner to generic manufacturers, distributors, and institutional purchasers.

Public company reports generally do not disclose Flagyl revenue as a separate line item. Pfizer reports revenue at broader product, business-unit, or portfolio levels, and Flagyl is not generally identified as a material standalone growth product in recent filings.[2] Sanofi and other historical commercial participants likewise have not provided a consistent public Flagyl revenue series that would support a reliable brand-specific forecast.

What drives Flagyl revenue today?

Current Flagyl-related revenue is influenced by:

• Generic substitution rates.
• Hospital purchasing agreements.
• Availability of low-cost oral and injectable products.
• Short treatment durations.
• Antimicrobial stewardship programs.
• Regional shortages or manufacturing interruptions.
• Demand for vaginal and topical metronidazole products.
• Brand-prescription persistence in selected clinical settings.

The branded product has limited pricing power. Metronidazole is inexpensive to manufacture, chemically stable, and available from multiple global suppliers. These characteristics make sustained premium pricing difficult.

When did Flagyl lose patent exclusivity?

Flagyl lost meaningful market exclusivity decades ago. Metronidazole was discovered and developed in the 1950s and entered clinical use in the 1960s. The original composition and early-use patent protections expired long before the modern generic-drug market.[3]

The relevant commercial conclusion is clear: Flagyl is not approaching a future loss of exclusivity. It is a post-exclusivity product with a mature generic market.

Exclusivity category	Current position
Original active-ingredient patent	Expired
Core composition-of-matter protection	Expired
New chemical entity exclusivity	Expired
Original branded formulation protection	Expired or commercially irrelevant
Current Orange Book patent barrier	No material barrier expected for standard metronidazole products
Pediatric exclusivity	Not a current commercial driver
Orphan exclusivity	Not applicable to the core product

What is the Orange Book status of Flagyl?

The FDA Orange Book records approved drug products, therapeutic-equivalence information, patents, and exclusivity where applicable.[4] Standard Flagyl and generic metronidazole products do not have the type of active patent estate associated with recently launched small-molecule drugs.

Orange Book analysis should distinguish between:

• The historical Flagyl NDA.
• Current or discontinued branded presentations.
• Generic abbreviated new drug applications.
• Dosage-form-specific approvals.
• Patent listings associated with newer formulations rather than the legacy oral product.

The absence of an active core patent does not eliminate every regulatory issue. A manufacturer still must demonstrate bioequivalence, comply with current good manufacturing practices, maintain supply reliability, and meet FDA requirements for labeling and postmarket safety reporting.

How many patents cover Flagyl and metronidazole?

No active patent portfolio is expected to protect the basic metronidazole molecule in the United States. Any remaining patent activity would more likely relate to a particular formulation, delivery system, combination, manufacturing process, or use rather than to Flagyl itself.

What formulations are protected by metronidazole patents?

Potentially relevant patent categories include:

• Controlled-release oral dosage forms.
• Mucoadhesive vaginal systems.
• Combination products.
• Dermatologic delivery systems.
• Nanoparticle or liposomal formulations.
• Methods that combine metronidazole with other active ingredients.
• Manufacturing processes that improve purity, particle size, or stability.

These patent categories generally do not restore exclusivity to conventional Flagyl tablets or standard intravenous metronidazole. Their commercial value depends on whether the formulation receives a distinct FDA approval, qualifies for listing in the Orange Book, and achieves meaningful clinical or reimbursement differentiation.

Are there Paragraph IV challenges to Flagyl?

Paragraph IV litigation is not a major current risk for legacy Flagyl because the relevant core patents have expired. Paragraph IV certifications may arise in connection with a specific newer metronidazole formulation or a listed patent, but such activity would concern that formulation rather than conventional Flagyl.

Under the Hatch-Waxman framework, an ANDA applicant may certify that a listed patent is invalid, unenforceable, or will not be infringed. For a mature product such as metronidazole, the principal competitive pathway is usually approval under an ANDA with no effective patent delay, not a high-value challenge to an active Flagyl patent estate.[5]

What generic entry risks exist for Flagyl?

Generic entry risk is already realized rather than prospective. The relevant issue is continued price erosion and supply competition.

Generic competitive factors

Factor	Effect on Flagyl economics
Multiple oral suppliers	Reduces branded share and pricing
Low manufacturing complexity	Lowers barriers to entry
Hospital tenders	Compresses injectable margins
Pharmacy substitution	Accelerates generic conversion
Limited brand differentiation	Weakens retention
Commodity active ingredient	Increases procurement sensitivity
Periodic shortages	Can temporarily improve supplier pricing

Metronidazole manufacturers compete on acquisition cost, supply continuity, wholesaler access, regulatory compliance, and dosage-form breadth. Brand loyalty is weaker than in chronic therapies because treatment courses are usually short and prescribing is indication-driven.

Which companies compete with Flagyl?

The competitive field includes the Flagyl brand owner or marketer, generic manufacturers, contract manufacturers, and distributors. The precise supplier list varies by dosage form and market.

In the United States, metronidazole products have historically been marketed by companies such as:

• Pfizer and its predecessor commercial organizations for Flagyl.
• Rising Pharmaceuticals.
• Teva Pharmaceuticals.
• Amneal Pharmaceuticals.
• Hikma Pharmaceuticals.
• Sandoz and other Novartis-related generic operations.
• Mylan, now part of Viatris.
• West-Ward, now associated with Hikma.
• Multiple contract and offshore active pharmaceutical ingredient suppliers.

The competitive set changes as manufacturers enter or withdraw, products move between corporate portfolios, and FDA manufacturing actions affect availability. The brand itself is less important to market share than the number of approved generic suppliers and the purchasing channel.

What is Flagyl’s FDA regulatory status?

Flagyl and metronidazole products have long-standing FDA approval histories. The approved uses cover anaerobic bacterial infections and protozoal diseases, subject to product-specific labeling.[1]

Important regulatory considerations include:

• Metronidazole is not a broad substitute for every bacterial infection.
• FDA labeling contains warnings concerning carcinogenicity findings in certain animal studies.
• Alcohol interaction warnings have historically been included in labeling and clinical guidance.
• Neurologic adverse reactions, including peripheral neuropathy and encephalopathy, are recognized safety concerns.
• Antimicrobial stewardship affects prescribing duration and indication selection.
• The FDA may take action against facilities or products that fail quality, labeling, or manufacturing requirements.

Regulatory value therefore lies in established clinical familiarity and approved indications, not in exclusivity.

What patent litigation affects Flagyl?

No major current litigation campaign appears to define the conventional U.S. Flagyl market. Legacy patent disputes, if any, are unlikely to affect present-day access to standard metronidazole.

Litigation risk is more relevant in four areas:

1. Product-liability claims involving neurologic or other adverse events.
2. FDA enforcement involving manufacturing or labeling.
3. Contract disputes between suppliers and purchasers.
4. Patent disputes involving reformulated or combination metronidazole products.

A conventional generic metronidazole tablet generally presents low patent litigation exposure. A reformulated product with a differentiated delivery mechanism could have materially higher litigation risk if its sponsor lists patents in the Orange Book.

Are there licensing deals involving Flagyl?

Flagyl’s historical commercialization involved predecessor companies and regional marketing arrangements, but current public reporting does not establish a material, separately disclosed licensing stream tied to the product.

The commercial structure today is more likely to involve:

• Generic supply agreements.
• Contract manufacturing.
• Wholesale distribution.
• Hospital group-purchasing contracts.
• Regional marketing rights.
• API procurement agreements.

These arrangements can affect availability and margin but do not create meaningful exclusivity for the legacy brand.

How strong is the Flagyl patent estate?

The patent estate is weak for the conventional product and potentially stronger only for narrow, differentiated formulations.

Asset category	Patent strength	Commercial implication
Metronidazole molecule	None for current U.S. exclusivity	Open generic competition
Conventional oral tablet	Very low	Generic substitution
Standard injectable product	Very low	Institutional price competition
Vaginal delivery formulation	Product-specific	Possible formulation differentiation
Topical dermatology formulation	Product-specific	Some brand and channel value
Novel combination or controlled release	Variable	Potentially protectable if clinically differentiated
Manufacturing process	Variable	May protect production economics, not market access broadly

For investment purposes, Flagyl should be treated as a mature generic-market product, not as a patent-backed pharmaceutical asset.

How does Flagyl compare with competing antimicrobial products?

Flagyl competes differently from newer antibiotics and from alternative therapies.

Product category	Relative position versus Flagyl
Oral metronidazole generics	Direct substitutes; lowest-cost competition
Tinidazole	Alternative nitroimidazole with different dosing and tolerability considerations
Clindamycin	Alternative for selected anaerobic infections; different resistance and adverse-event profile
Vancomycin	Used for different clinical situations, including selected C. difficile treatment
Fidaxomicin	More specialized and higher-priced treatment for C. difficile
Secnidazole	Longer-acting nitroimidazole alternative in selected indications
Newer broad-spectrum antibiotics	May offer different coverage but generally at higher cost and with stewardship restrictions

Flagyl retains demand because of low cost, broad clinical familiarity, oral and injectable availability, and utility against anaerobic and protozoal pathogens. Its weaknesses include tolerability, drug-interaction concerns, resistance limitations, and competition from newer indication-specific products.

What is the geographic coverage of Flagyl?

Metronidazole is marketed globally under Flagyl and numerous local or generic names. Geographic economics differ materially:

• United States: mature generic market with extensive substitution.
• Europe: national reimbursement systems and generic tendering dominate pricing.
• Emerging markets: branded generics can retain more visibility, but local competition remains intense.
• Hospital markets: injectable availability and procurement contracts are critical.
• Low- and middle-income markets: affordability supports volume, while regulatory and quality standards vary by jurisdiction.

The global product is commercially durable but not geographically uniform. Brand value tends to be higher where physicians prescribe branded generics or where distributor relationships influence pharmacy selection.

What manufacturing and intellectual-property barriers exist?

Manufacturing barriers are moderate from a quality and compliance perspective but low from an intellectual-property perspective.

A supplier must manage:

• Consistent API quality.
• Impurity control.
• Dissolution and bioequivalence requirements.
• Sterility for injectable products.
• Packaging and stability.
• FDA inspection readiness.
• Reliable API sourcing.
• Shortage prevention.
• Pharmacovigilance and labeling compliance.

The greatest operational risk is not patent infringement. It is a manufacturing disruption, regulatory warning letter, failed inspection, or API shortage that removes a supplier from the market. Temporary supply constraints can create short-term pricing opportunities, but they do not create durable franchise value.

What is the outlook for Flagyl revenue and market value?

Flagyl revenue is likely to remain stable to declining in nominal terms, with volume supported by established clinical use and pricing constrained by generic competition. The brand’s financial profile is defensive in volume but weak in margin and growth.

Base-case trajectory

• Brand share continues to decline.
• Generic metronidazole remains widely available.
• Oral products retain high unit volume but low pricing.
• Injectable products remain important in hospitals.
• Vaginal and topical formulations provide pockets of differentiated demand.
• No material patent-driven price increase is expected.
• Revenue disclosure remains limited because the product is not reported as a major standalone franchise.

Upside conditions

A supplier could improve economics through:

• A shortage affecting competing manufacturers.
• A differentiated delivery system.
• A branded generic strategy in selected markets.
• A new combination product.
• Hospital supply contracts with reliable availability.
• Regulatory approval for a specialized indication.

Downside conditions

The principal downside factors are:

• Further generic price erosion.
• Supplier consolidation followed by aggressive tendering.
• Antimicrobial stewardship reducing unnecessary use.
• Manufacturing shutdowns or quality failures.
• Substitution by newer, indication-specific products.
• Declining brand recognition among prescribers and pharmacists.

Key Takeaways

• Flagyl is the legacy brand of metronidazole and is a mature, off-patent antimicrobial.
• Core composition-of-matter and early product protections expired decades ago.
• Standard Flagyl tablets and injectable products face no material current patent barrier.
• Generic substitution, low prices, and institutional purchasing determine market economics.
• Brand-specific revenue is not separately disclosed in a reliable public series.
• Current value is concentrated in generic supply, hospital contracts, and selected vaginal or topical formulations.
• Paragraph IV risk is limited for conventional Flagyl but can arise for newer metronidazole formulations.
• Manufacturing quality, API availability, and regulatory compliance are more important than patent protection.
• The likely financial trajectory is stable-to-declining revenue, low margin, and limited growth absent a differentiated formulation.

FAQs About Flagyl Market Exclusivity and Commercial Risk

Is Flagyl still a branded drug?

Yes. Flagyl remains a recognized brand, but most U.S. prescriptions for metronidazole are filled with generic products because the core medicine is long off patent.

Can a company launch a generic version of Flagyl?

Yes. A company can seek FDA approval for an appropriate metronidazole product through the ANDA pathway, subject to bioequivalence, manufacturing, labeling, and other regulatory requirements.

Does Flagyl have biosimilar risk?

No. Metronidazole is a small-molecule chemical drug, not a biologic. Biosimilar rules do not apply. Its competitive risk comes from generic drugs and branded generics.

Which Flagyl formulation has the greatest commercial differentiation?

Vaginal, topical, controlled-release, and combination formulations can have greater differentiation than conventional oral tablets. Their value depends on clinical evidence, reimbursement, patent scope, and regulatory approval.

Is Flagyl a potential target for pharmaceutical licensing or acquisition?

The legacy brand alone has limited strategic value. A transaction would be more commercially compelling if it included reliable manufacturing, shortage-prone injectable capacity, geographic rights, or a differentiated metronidazole formulation.

References

1. U.S. Food and Drug Administration. (2023). Flagyl (metronidazole) prescribing information. FDA.
2. Pfizer Inc. (2024). Annual report for the fiscal year ended December 31, 2023. Pfizer.
3. National Library of Medicine. (2024). Metronidazole: Drug information and historical development. MedlinePlus and DailyMed resources.
4. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
5. U.S. Food and Drug Administration. (2024). Abbreviated new drug application process and patent certifications. FDA.

DrugChatter Q&A for FLAGYL

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