FLAGYL I.V. Drug Patent Profile

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

Flagyl I.v. is a drug marketed by Pfizer and Baxter Hlthcare and is included in two NDAs.

The generic ingredient in FLAGYL I.V. is metronidazole. There are two drug master file entries for this compound. Sixty-six suppliers are listed for this compound. Additional details are available on the metronidazole profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Flagyl I.v.

A generic version of FLAGYL I.V. was approved as metronidazole by TEVA PHARMS USA on November 6^th, 1984.

Summary for FLAGYL I.V.

US Patents:	0
Applicants:	2
NDAs:	2
Raw Ingredient (Bulk) Api Vendors:	31
Clinical Trials:	77
Patent Applications:	1,937
DailyMed Link:	FLAGYL I.V. at DailyMed

Recent Clinical Trials for FLAGYL I.V.

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 I.V. clinical trials

US Patents and Regulatory Information for FLAGYL I.V.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Pfizer	FLAGYL I.V.	metronidazole hydrochloride	INJECTABLE;INJECTION	018353-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Baxter Hlthcare	FLAGYL I.V. RTU IN PLASTIC CONTAINER	metronidazole	INJECTABLE;INJECTION	018657-001	Approved Prior to Jan 1, 1982	AP	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

Flagyl I.V. Market Dynamics, Patent Status and Financial Trajectory

Last updated: October 28, 2026

Flagyl I.V. is the intravenous formulation of metronidazole, an established antibacterial and antiprotozoal used primarily in hospitals for anaerobic infections, surgical prophylaxis, and selected protozoal diseases. Its U.S. market is mature, genericized, and procurement-driven. The brand has no meaningful exclusivity advantage, while generic metronidazole injection competes mainly on price, supply reliability, contract access, and hospital formulary position.

Product-level revenue for Flagyl I.V. is not publicly disclosed by Pfizer or other commercial participants. The financial trajectory is therefore best assessed through market structure: long-expired intellectual property, multiple generic suppliers, low unit pricing, hospital purchasing concentration, periodic shortages, and limited clinical differentiation.

What is Flagyl I.V. and how is it used?

Flagyl I.V. contains metronidazole, a nitroimidazole antimicrobial active against many anaerobic bacteria and protozoa. The U.S. label identifies intravenous use when oral therapy is not feasible or when a rapid parenteral route is clinically appropriate.[1]

What are the main clinical applications?

Flagyl I.V. is used in:

• Intra-abdominal infections involving anaerobic organisms
• Pelvic and gynecologic infections
• Skin and skin-structure infections caused by anaerobes
• Lower respiratory tract infections, including selected anaerobic pneumonia cases
• Bacterial septicemia involving susceptible anaerobes
• Surgical prophylaxis, especially colorectal procedures
• Amebiasis and other protozoal infections when intravenous treatment is required

The product is typically supplied in premixed intravenous containers, commonly 500 mg in 100 mL. Hospital use depends on antimicrobial stewardship protocols, infection type, renal and hepatic function, and availability of oral therapy.

How does Flagyl I.V. compare with oral metronidazole?

Attribute	Flagyl I.V.	Oral metronidazole
Route	Intravenous infusion	Tablet, capsule, or oral suspension
Primary setting	Hospital and inpatient care	Hospital, outpatient, and specialty care
Cost structure	Higher acquisition and administration cost	Lower product and administration cost
Use case	Patients unable to take oral therapy or requiring parenteral treatment	Patients able to absorb and tolerate oral treatment
Competition	Generic injectable suppliers	Numerous generic oral suppliers
Commercial differentiation	Limited	Very limited

Hospitals often convert patients from intravenous to oral metronidazole when clinically appropriate. That conversion reduces demand for the injectable formulation and places pressure on volume growth.

What is the FDA regulatory status of Flagyl I.V.?

Flagyl I.V. is an approved prescription drug marketed under an older full New Drug Application. The active ingredient, metronidazole, has been used in the United States for decades, and generic injectable versions are approved through abbreviated new drug applications.

The principal regulatory characteristics are:

Regulatory factor	Status
Active ingredient	Metronidazole
Dosage form	Intravenous injection or infusion
Regulatory pathway for generics	ANDA
FDA approval status	Established product category with generic competition
Pediatric labeling	Included in product labeling, subject to indication and dosing limitations
Controlled-substance status	Not a controlled substance
Biosimilar exposure	None
Regulatory exclusivity	No meaningful current exclusivity identified

FDA-approved labeling warns about carcinogenicity findings in certain animal studies, neurologic adverse reactions, peripheral neuropathy, encephalopathy, seizures, drug interactions, and alcohol-related disulfiram-like reactions.[1]

What is the Orange Book status of Flagyl I.V.?

The Orange Book is relevant because it records approved products, therapeutic equivalence ratings, patents, and regulatory exclusivity. Metronidazole injection is a mature small-molecule product with generic competition and no commercially meaningful remaining reference-product exclusivity.

Are there active patents protecting Flagyl I.V.?

No active composition-of-matter or formulation patent is known to provide meaningful protection for Flagyl I.V. in the United States. The foundational patents associated with metronidazole and the original Flagyl product expired many years ago.

The principal patent conclusions are:

• No surviving basic-compound patent blocks generic metronidazole injection.
• No current patent is widely recognized as protecting the standard 500 mg/100 mL hospital presentation.
• Generic manufacturers do not face a conventional patent barrier to filing or marketing approved injectable metronidazole.
• Commercial risk is concentrated in manufacturing, quality, supply, and contracting rather than patent litigation.

Because the product is old and genericized, the Orange Book listing does not create a durable market moat for the brand. Any current patent activity would need to involve a specific container, delivery system, manufacturing process, or newly developed formulation rather than standard metronidazole itself.[2]

When did Flagyl I.V. lose exclusivity?

Flagyl I.V. lost practical exclusivity decades ago. Metronidazole was first approved in the United States in the 1960s, and the relevant patent and regulatory exclusivity periods have long expired.[3]

Exclusivity timeline

Event	Approximate timing	Commercial effect
Initial U.S. metronidazole approvals	1960s	Originator launch
Original patent protection	Expired decades ago	Opened product to generic competition
Generic oral competition	Established for many years	Reduced brand pricing power
Generic injectable competition	Established for many years	Reduced Flagyl I.V. volume and price
Current market	Mature generic market	Supply and contracting determine access

Flagyl I.V. is therefore not an exclusivity-driven asset. Any remaining branded demand reflects physician familiarity, institutional preference, legacy contracts, or supply continuity rather than patent protection.

How many patents cover Flagyl I.V.?

No meaningful patent estate currently protects the standard Flagyl I.V. product. Patent counts can be misleading because historical patents, expired patents, continuation applications, and patents covering unrelated metronidazole products may appear in patent databases.

For commercial analysis, the relevant conclusion is:

Patent category	Current competitive significance
Metronidazole compound patents	None; expired
Standard intravenous formulation patents	No meaningful barrier identified
Method-of-use patents for established indications	Limited or expired
Container or packaging patents	Potentially relevant only to a specific supplier
Manufacturing-process patents	May protect a process, but not the active ingredient market
Patent litigation risk	Low relative to supply and quality risk

A generic applicant would generally expect to rely on the absence of blocking patents or file a Paragraph IV certification only if a relevant listed patent remained in force. For standard metronidazole injection, Paragraph IV litigation is not the central market-entry issue.

Which companies compete with Flagyl I.V.?

The competitive field includes the branded product and multiple generic suppliers. Supplier participation can vary by country, dosage strength, package configuration, manufacturing status, and hospital contract.

U.S. competitive structure

Typical market participants have included:

• Pfizer or its applicable commercial successor for branded Flagyl products
• Fresenius Kabi
• Hikma Pharmaceuticals
• Sagent Pharmaceuticals, including products acquired or commercialized through broader corporate transactions
• Baxter and other hospital-injection suppliers in relevant periods
• Smaller ANDA holders and contract manufacturers

The exact supplier roster changes because injectable products are frequently affected by manufacturing discontinuations, facility remediation, shortages, and portfolio rationalization. FDA’s Drugs@FDA and Drug Shortages databases are the primary sources for current approval and availability information.[4][5]

How does Flagyl I.V. compare with generic metronidazole injection?

Factor	Flagyl I.V. brand	Generic metronidazole injection
Patent protection	None of practical significance	None required to enter once approved
Clinical efficacy	Same active ingredient and approved strength	Therapeutically equivalent where rated substitutable
Price	Usually higher	Usually lower
Hospital purchasing	Limited by contract economics	Favored by group purchasing organizations
Brand loyalty	May persist in legacy institutions	Weak
Supply differentiation	Depends on manufacturer	Often the decisive variable
Litigation risk	Low	Low
Margin outlook	Compressed	Volume-dependent, often thin

The main basis for competition is not innovation. It is reliable delivery of a sterile injectable product at a low contracted price.

What generic entry risks exist for Flagyl I.V.?

Generic entry risk is effectively realized rather than prospective. Flagyl I.V. already operates in a generic market.

The commercial risks are:

1. Continued price erosion from additional suppliers.
2. Hospital conversion from branded to generic product.
3. Intravenous-to-oral conversion programs.
4. Reduced procedure volumes or shorter inpatient stays.
5. Group purchasing organization negotiations.
6. Supplier shortages that shift demand temporarily between manufacturers.
7. Manufacturing failures involving sterility, particulate matter, container integrity, or plant capacity.
8. Product discontinuation if margins do not justify continued supply.

The largest near-term opportunity for an individual supplier is often shortage substitution. That opportunity can increase volume without creating durable pricing power. Once supply normalizes, hospitals may return to lowest-cost contracted sourcing.

What patent litigation affects Flagyl I.V.?

No major current U.S. patent litigation is broadly associated with the standard Flagyl I.V. product. The absence of litigation is consistent with the product’s age, lack of meaningful patent exclusivity, and generic market structure.

Are there Paragraph IV challenges?

Paragraph IV litigation is not a material current market driver for conventional metronidazole injection. Generic entrants have generally relied on an expired-patent or no-blocking-patent framework rather than a high-value challenge to a modern branded patent estate.

Any future dispute would be more likely to concern:

• A proprietary delivery device
• A novel premixed container
• A manufacturing process
• A specialized concentration or formulation
• Regulatory compliance or product quality

These issues would affect a particular supplier rather than the whole metronidazole injection market.

What formulations are protected by Flagyl I.V.?

The standard Flagyl I.V. formulation is a ready-to-use intravenous metronidazole solution. Its commercial value comes from hospital convenience and sterile manufacturing, not from a current formulation patent moat.

Formulation and manufacturing considerations

Injectable metronidazole requires:

• Sterile production
• Validated aseptic or terminal sterilization processes, as applicable
• Container-closure integrity
• Control of particulate matter
• Stability through shelf life
• Compatibility with infusion equipment
• Reliable access to pharmaceutical-grade metronidazole and packaging components

These requirements create operational barriers. They do not create the same legal exclusivity as a patent. A company with an approved ANDA can compete, but maintaining sterile injectable capacity is more difficult than manufacturing a conventional oral tablet.

Manufacturing capacity can therefore produce temporary commercial advantages. A supplier with available inventory may gain hospital volume during a shortage, while a plant interruption can rapidly eliminate its sales.

How does Flagyl I.V. generate revenue?

Flagyl I.V. revenue is generated through hospital and institutional channels rather than direct-to-consumer demand. The main channels are:

• Hospital direct purchasing
• Group purchasing organizations
• Integrated delivery networks
• Wholesalers and distributors
• Government and institutional tenders
• Specialty hospital pharmacies

Why are Flagyl I.V. margins under pressure?

Revenue and margins are constrained by four structural factors:

• The active ingredient is old and widely available.
• Therapeutic substitution is straightforward.
• Hospitals negotiate aggressively.
• Oral metronidazole can replace intravenous treatment for eligible patients.

Injectable products can retain better pricing than oral solids when the supplier base is narrow or shortages occur. That pricing benefit is unstable. Increased supplier participation generally pushes prices lower, while manufacturing disruptions can create short-term price spikes.

What is the financial trajectory for Flagyl I.V.?

A separate, audited Flagyl I.V. revenue series is not publicly disclosed. Pfizer’s public reporting does not provide a standalone Flagyl I.V. line item, and generic manufacturers generally report broader hospital-product or injectable portfolios rather than product-specific metronidazole sales.[6]

The likely financial trajectory is:

Period	Market condition	Financial implication
Originator period	Brand-led, limited competition	Higher pricing and stronger margins
Early generic period	Multiple entrants	Rapid price and share erosion
Mature generic period	Contract-driven purchasing	Low growth and thin margins
Shortage periods	Reduced supplier availability	Temporary volume and price improvement for in-stock suppliers
Long-term outlook	Stable clinical demand, mature competition	Flat-to-declining nominal revenue absent supply disruption

Revenue exposure is therefore modest for diversified pharmaceutical companies but can be material for a small injectable manufacturer with concentrated hospital exposure. For Pfizer, Flagyl I.V. is unlikely to be a major financial driver relative to its innovative medicines and larger established brands. For generic suppliers, the product can contribute recurring hospital revenue but is unlikely to support premium valuation without a broader injectable portfolio.

What factors will shape the Flagyl I.V. market through 2030?

Demand drivers

Demand should remain supported by:

• Persistent anaerobic infections
• Continued colorectal and gynecologic surgery
• Hospital use in patients unable to take oral therapy
• Global availability of metronidazole as a low-cost antimicrobial
• Clinical familiarity and established treatment guidelines

Demand constraints

Growth is limited by:

• Antimicrobial stewardship
• Intravenous-to-oral conversion
• Shorter hospital stays
• Reduced use of prophylactic antibiotics where guidelines narrow treatment
• Competition from alternative anaerobic agents
• Hospital cost-containment programs

Supply-side risks

The strongest market risk is supply interruption. Sterile injectables have historically shown vulnerability to plant shutdowns, quality investigations, component shortages, and low-margin portfolio exits. FDA’s shortage database should be monitored more closely than patent filings for near-term commercial changes.[5]

How strong is the Flagyl I.V. patent estate?

The patent estate is weak from a current commercial perspective. A concise assessment is:

Dimension	Assessment
Composition-of-matter protection	Expired
Formulation protection	No meaningful standard-product barrier identified
Method-of-use protection	Limited or expired for established uses
Generic entry barrier	Low
Patent litigation exposure	Low
Manufacturing barrier	Moderate
Regulatory complexity	Moderate for sterile injectable production
Pricing power	Low
Supply disruption sensitivity	High

The product’s defensibility is operational rather than intellectual property-based. Reliable sterile manufacturing, regulatory compliance, inventory, and institutional contracting matter more than patent ownership.

Key Takeaways

• Flagyl I.V. is intravenous metronidazole for hospital treatment of anaerobic infections and selected protozoal diseases.
• U.S. patent and regulatory exclusivity expired decades ago.
• Generic injectable metronidazole is the primary competitive threat and already controls the market structure.
• No major current Paragraph IV or patent-litigation issue defines the product’s outlook.
• The standard formulation has limited legal protection, although sterile manufacturing creates operational barriers.
• Product-level revenue is not publicly disclosed by Pfizer or generic suppliers.
• Long-term revenue is likely stable to declining in normal supply conditions, with temporary gains during shortages.
• Hospital contracts, group purchasing organizations, generic substitution, and intravenous-to-oral conversion determine commercial performance.
• The principal investment and supply risk is manufacturing continuity, not patent expiry.

FAQs About Flagyl I.V. Market and Exclusivity

Does Flagyl I.V. still have brand exclusivity?

No. The relevant metronidazole patent and regulatory exclusivity periods expired long ago. The product competes in a mature generic market.

Is Flagyl I.V. interchangeable with generic metronidazole injection?

Where an FDA-approved generic has an applicable therapeutic-equivalence rating and the same relevant dosage form and strength, substitution may be permitted under state pharmacy and institutional policies. Hospital protocols govern actual use.

Does Flagyl I.V. have biosimilar competition?

No. Metronidazole is a small-molecule drug, not a biologic. Its competitors are generic drugs approved through ANDAs, not biosimilars.

Can a new company enter the metronidazole injection market?

Yes, subject to FDA approval, sterile manufacturing capability, product quality requirements, adequate supply, and commercial access to hospital contracts. Patent barriers are not the primary constraint.

What would cause Flagyl I.V. sales to increase?

Sales could rise temporarily if competing suppliers experience shortages, if hospital demand increases, or if a manufacturer wins new institutional contracts. Sustained growth is constrained by mature clinical demand and generic price competition.

References

1. U.S. Food and Drug Administration. (2023). Flagyl I.V. (metronidazole injection) prescribing information. Pfizer Laboratories. https://labeling.pfizer.com
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
3. U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/
4. U.S. Food and Drug Administration. (2024). Metronidazole injection: Drugs@FDA records. https://www.accessdata.fda.gov/scripts/cder/daf/
5. U.S. Food and Drug Administration. (2024). Drug shortages database. https://www.accessdata.fda.gov/scripts/drugshortages/
6. Pfizer Inc. (2024). Annual report 2023. https://www.pfizer.com/investors/financials/annual-reports-and-proxy-statements