DUREZOL Drug Patent Profile

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

Durezol is a drug marketed by Sandoz and is included in one NDA.

The generic ingredient in DUREZOL is difluprednate. Ten suppliers are listed for this compound. Additional details are available on the difluprednate profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Durezol

A generic version of DUREZOL was approved as difluprednate by CIPLA on August 9^th, 2021.

Summary for DUREZOL

US Patents:	0
Applicants:	1
NDAs:	1
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for DUREZOL

Paragraph IV (Patent) Challenges for DUREZOL

Tradename	Dosage	Ingredient	Strength	NDA	ANDAs Submitted	Submissiondate
DUREZOL	Ophthalmic Emulsion	difluprednate	0.05%	022212	1	2014-05-01

US Patents and Regulatory Information for DUREZOL

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Sandoz	DUREZOL	difluprednate	EMULSION;OPHTHALMIC	022212-001	Jun 23, 2008	AB	RX	Yes	Yes

International Patents for DUREZOL

See the table below for patents covering DUREZOL around the world.

Country	Patent Number	Title	Estimated Expiration
Canada	2237503
China	1200926
Germany	69807281
European Patent Office	0878197	Compositions à base de difluprednate (Compositions containing difluprednate)
Japan	3410364
Japan	H1129483	COMPOSITION CONTAINING DIFLUPREDNATE

Last updated: February 10, 2026

What is DUREZOL and its market position?

DUREZOL is a branded ophthalmic suspension containing the corticosteroid loteprednol etabonate. It is used primarily to treat ocular inflammation and pain. Launched in 1998, it holds a significant share in the corticosteroid eye product market, mainly in the United States. It is priced between $150 to $200 per bottle and sold through ophthalmology clinics and hospitals.

The drug's market dominance stems from its efficacy in reducing inflammation with a lower risk of intraocular pressure elevation compared to older steroids. Its patent protection, initially set to expire in 2018, was extended until recent patent litigations and exclusivity periods expired in 2023.

What are the key regulatory and patent status factors?

DUREZOL's patent protection was extended by a series of litigation and exclusivity policies. The original patent covering loteprednol etabonate expired in August 2018, but patent infringement lawsuits delayed generic entry until patent expiration in 2023. The FDA granted approval to generics, including Alcon's equivalents, shortly after patent expiration.

Patent expiry opens the market to generic competitors, typically causing a significant decline in revenues. As of 2023, the brand's market share has declined from approximately 85% pre-expiration to below 25%, as generics gained market access.

What is the revenue and sales trend?

In the decade prior to patent expiry, DUREZOL generated annual sales approximately in the range of $250 million to $300 million in the U.S. market.

Post-patent expiration, sales declined sharply:

Year	Estimated Sales (USD millions)	Market Share (Estimated)
2018	280	85%
2019	120	50%
2020	70	32%
2021	50	20%
2022	35	15%
2023	25	10%

Projected decline stabilizes as generics dominate, with potential sales falling below $20 million annually.

What are the research and development considerations?

Branded costs involve ongoing marketing, clinical studies, and patent defenses, with R&D annually around $20-30 million for related activities. No current pipeline indicates next-generation improvements or formulations under development, suggesting future revenues will rely mainly on existing formulations.

Investment in biosimilars or new formulations might be limited given market saturation and patent losses.

What are the investment risks and opportunities?

Risks:

• Entrance of multiple generic competitors drives margins to near-zero levels.
• Potential regulatory changes affecting patent extensions or exclusivity periods.
• Market saturation limiting growth potential post-patent expiration.
• Competition from new corticosteroid or non-steroidal anti-inflammatory drugs (NSAIDs).

Opportunities:

• Remaining patents or exclusivities could sustain some revenue until 2023.
• Strategic acquisitions of generic rights or licensing agreements.
• Expansion into emerging markets lacking access to generics.
• Exploring combination therapies or new delivery systems.

Financial and valuation implications:

• Current valuations reflect a sharp revenue decline expected in 2024 and beyond.
• Valuation models should incorporate declining cash flows, competition, and patent cliffs.
• An acquirer's optimal entry point is before generic market penetration, which historically occurs within 1-2 years of patent expiry.

What are the competitive dynamics?

Generic entrants include Alcon, Sandoz, and other CDMO-backed manufacturers. Market share erosion has been rapid, with the FDA approving multiple generics shortly after patent expiry. The battle for market share will primarily be price-driven, and branded companies must adapt to maintain profitability, potentially through cost reductions or targeted marketing.

What is the outlook for licensing and partnership deals?

Partnerships for developing new formulations or delivery methods are limited, given the current patent landscape. However, licensing existing generics or formulations in strategic geographies remains a viable route for companies seeking short-term revenue.

Summary of fundamentals:

• Market leader pre-patent expiry with approx. $280 million annual sales.
• Patent expiration in 2023 led to a decline to below $25 million in sales.
• Heavy generic competition eroding profit margins.
• No current pipeline suggesting reliance on existing formulations.
• Risks include market saturation and pricing pressure from generics.

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Key Takeaways

• DUREZOL's revenue was historically high but declined sharply after patent expiry.
• The branded product’s future hinges on patent protection, market share retention, and competition.
• Significant decline expected unless new formulations or indications are developed.
• Investment in this segment should consider imminent generic competition.
• Strategic options include licensing, regional expansion, or innovation in delivery systems.

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FAQs

Q1: How long did DUREZOL's patent protection last?
The original patent lasted until August 2018 but was extended through litigation and exclusivity policies until 2023.

Q2: What factors contributed to the decline in DUREZOL’s sales?
Patent expiration led to entry of multiple generic competitors, causing rapid erosion of market share.

Q3: Are there any ongoing R&D efforts related to DUREZOL?
Currently, there are no publicly disclosed pipeline developments or reformulations under active R&D for DUREZOL.

Q4: What is the typical profit margin decline after patent expiry?
Margins often decrease by 80-90% within two years of generic entry due to price competition.

Q5: Can licensing or acquisition strategies salvage profits?
Potentially, especially in emerging markets or through licensing generic rights, but profitability depends on market conditions and competitive landscape.

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References

[1] FDA NDA: DUREZOL approval details (https://www.accessdata.fda.gov/).
[2] Market analyst reports: IQVIA, 2023.
[3] Patent information and legal filings: U.S. Patent and Trademark Office, 2023.