US Patent 8,067,451: Claims, Scope, Expiration Risk, and Duexis Patent Landscape

US Patent 8,067,451 protects a specific immediate-release combination tablet containing 800 mg ibuprofen and 26.6 mg famotidine. Its central technical requirement is physical separation of the famotidine portion from the ibuprofen portion by a defined barrier layer containing hypromellose, polyethylene glycol, polysorbate 80, and titanium dioxide.

The patent also claims the tablet’s stability profile, rapid co-release, three-times-daily administration, and use to reduce ibuprofen-induced ulcer risk in patients with rheumatoid arthritis, osteoarthritis, or other pain indications. The claims correspond closely to the approved Duexis product, marketed by Horizon Pharma and later associated with other Horizon entities.

What product does US Patent 8,067,451 protect?

The patent protects a bilayer or multi-portion immediate-release tablet in which:

Element	Claimed requirement
Ibuprofen dose	800 mg
Famotidine dose	26.6 mg
Famotidine structure	A separate second portion
Barrier layer	Hydroxypropyl methylcellulose 2910, polyethylene glycol 400, polysorbate 80, and titanium dioxide
Separation	Barrier layer completely separates famotidine from ibuprofen
Release profile	Rapid release of both active ingredients at approximately the same time
Stability	No more than approximately 0.5% total famotidine impurities after one month at 40°C and 75% relative humidity
Delivery system	Not enteric-coated and not sustained-release or delayed-release
Administration	Three times daily
Daily famotidine exposure	Approximately 80 mg
Medical purpose	Reducing the risk of ibuprofen-induced ulcers

The claims are narrower than a broad claim to any ibuprofen-famotidine combination. A competing product containing the same active ingredients could avoid literal infringement if it uses different strengths, a different physical architecture, a different coating composition, a different release profile, or a different dosing regimen.

How are the claims organized?

Claims 1, 8, and 10 are the principal independent claims.

Claim 1: Combination tablet claim

Claim 1 is a product claim with extensive structural, functional, stability, and intended-use limitations. It requires all of the following:

An oral tablet.
A first portion containing 800 mg ibuprofen.
A second portion containing 26.6 mg famotidine.
Complete separation of the second portion from the first by the specified barrier layer.
A defined stability result under accelerated storage conditions.
Rapid, approximately simultaneous release.
No enteric, sustained-release, or delayed-release formulation.
TID use for prevention of ibuprofen-induced ulcers.
Use in specified ibuprofen-responsive conditions.
Exclusion of patients with certain acid-related or reflux conditions.

The structural limitations are likely to carry the greatest weight in an abbreviated new drug application challenge. The stability and release limitations may become important if a proposed generic uses a different coating process or formulation.

Claim 8: Method-of-treatment claim

Claim 8 covers administering three doses of the claimed tablet under a TID schedule. The total daily famotidine dose is approximately 80 mg.

The method claim requires:

A patient at risk of ibuprofen-induced ulcers;
An ibuprofen-responsive condition;
A first, second, and third dose;
TID administration;
Reduction of ulcer risk;
Reduction of the symptom requiring ibuprofen; and
The same patient exclusions recited in claim 1.

Because claim 8 is a method claim, infringement generally depends on the acts of prescribing, instructing, or administering the regimen. A generic applicant may seek to limit its labeling through a section viii statement or other carve-out, but the commercial exposure depends on the final approved labeling, marketing conduct, and actual prescribing behavior.

Claim 10: “Consisting essentially of” composition claim

Claim 10 covers a composition “consisting essentially of” the same two active portions and barrier layer. This transitional phrase generally permits additional ingredients that do not materially affect the claimed basic and novel characteristics.

The key characteristics are likely:

Separation of ibuprofen and famotidine;
Famotidine stability;
Rapid and approximately simultaneous release;
Immediate-release behavior;
The specified dosage strengths.

Claim 10 may provide broader commercial coverage than claim 1 with respect to unrecited excipients, but it remains limited by the same dosage, coating, separation, stability, and release requirements.

What formulations are protected by the patent?

The patent protects a formulation architecture rather than merely a chemical combination.

Barrier-layer technology

The barrier layer contains:

Hydroxypropyl methylcellulose 2910;
Polyethylene glycol 400;
Polysorbate 80; and
Titanium dioxide.

The barrier prevents direct or excessive interaction between ibuprofen and famotidine during manufacture and storage. Ibuprofen can create formulation conditions that degrade famotidine. The claimed coating therefore has both a physical separation function and a chemical-stability function.

A formulation using a different polymer, plasticizer, surfactant, pigment, or coating system may present a non-infringement position. That position would depend on whether the substitute system satisfies the claim language literally or under the doctrine of equivalents.

Microcrystalline cellulose

Claims 5 and 7 add microcrystalline cellulose to the famotidine portion. These dependent claims provide narrower protection for a formulation using that excipient.

Microcrystalline cellulose may affect tablet compression, content uniformity, disintegration, and the physical integrity of the famotidine-containing portion. It does not independently define the patented product. It narrows the claim to one excipient configuration.

Release profile

Claims 3 and 4 impose in vitro release thresholds:

Claim	Ibuprofen release	Famotidine release	Time	pH
3	At least 60%	At least 60%	Within 20 minutes	6.8 to 7.4
4	At least 75%	At least 75%	Within 20 minutes	6.8 to 7.4

A product that uses the same active ingredients and coating but releases one ingredient more slowly could challenge infringement under these limitations. The testing method, apparatus, medium, agitation, sampling, and analytical method would be material to any dispute.

How strong is the patent estate for Duexis?

US Patent 8,067,451 has a relatively focused claim set. Its commercial strength comes from the combination of multiple limitations that map onto the approved fixed-dose product.

Strengths

The patent has several features that can increase enforcement value:

It covers the precise 800 mg/26.6 mg strength combination.
It claims physical separation of the active ingredients.
It claims a named barrier-layer composition.
It includes a stability limitation directed to famotidine degradation.
It covers the TID regimen and approximately 80 mg daily famotidine dose.
It includes both product and method claims.
It claims immediate, approximately simultaneous release rather than a conventional delayed-release proton-pump-inhibitor design.

Vulnerabilities

The same limitations create potential attack points:

The barrier-layer composition is specific.
The stability limitation may require extensive testing and claim-construction analysis.
The release limitations create a laboratory-testing issue.
The medical-use language may narrow enforcement against products with restricted labeling.
The patient exclusions may complicate proof of method infringement.
A competitor could pursue a formulation with a different separation system or different strengths.

The patent is stronger against a direct copy of Duexis than against a redesigned ibuprofen-famotidine product.

When does US Patent 8,067,451 lose exclusivity?

Patent expiration depends on the patent’s effective filing date, priority chain, patent-term adjustment, patent-term extension, and terminal disclaimers. A patent’s issue date alone does not determine expiration.

US Patent 8,067,451 issued on November 29, 2011. Public patent records associate it with the ibuprofen-famotidine combination product covered by Duexis. The relevant commercial question is the effective expiration date recorded for the patent and any Orange Book-listed patent term.

A standard 20-year term calculation based on a 2009 nonprovisional filing would place nominal expiration in 2029, subject to patent-term adjustment and any earlier effective filing date in the priority chain. The authoritative date is the USPTO patent-term record and the current FDA Orange Book entry, not a calculation based only on the issue date.

Regulatory exclusivity

The FDA approved Duexis in 2011. New-drug exclusivity and patent exclusivity are separate rights:

Regulatory exclusivity restricts certain FDA approval pathways for a defined period.
Patent exclusivity can continue after regulatory exclusivity ends.
A generic applicant may challenge patents before patent expiration through an ANDA Paragraph IV certification.
A patent listed in the Orange Book can trigger a statutory stay when the sponsor files an infringement action within the applicable period.

The relevant regulatory sources are the Duexis approval records, the FDA prescribing information, and the current Orange Book patent listing. [FDA, 2024a; FDA, 2024b]

What is the Orange Book status of US Patent 8,067,451?

US Patent 8,067,451 is associated with the Duexis fixed-dose combination of ibuprofen and famotidine. The Orange Book analysis should distinguish among:

Whether the patent is currently listed;
The listed patent expiration date;
The FDA use code;
Whether the listing covers the drug substance, formulation, or method of use; and
Whether a pending ANDA contains a Paragraph IV certification.

The patent’s claims are primarily formulation and method-of-use claims. They do not claim ibuprofen or famotidine as new chemical entities. A generic applicant could therefore confront formulation and use-code issues rather than a basic active-ingredient patent.

Which companies could challenge the patent?

Potential challengers would include ANDA applicants seeking approval for an ibuprofen-famotidine product or an equivalent fixed-dose combination. A challenge could use one or more of the following positions:

Challenge theory	Relevant claim vulnerability
Non-infringement	Different barrier layer, dosage, release profile, or manufacturing architecture
Anticipation	Earlier disclosure of the same separated immediate-release combination
Obviousness	Combination of known ibuprofen and famotidine formulations with predictable separation techniques
Indefiniteness	Ambiguity in “about,” “rapidly,” “about the same time,” or “consisting essentially of”
Written description or enablement	Whether the specification supports the full scope of the stability and release limitations
Method carve-out	Removal or restriction of ulcer-prevention language from generic labeling
Process redesign	Manufacturing a famotidine-containing portion outside the claimed coating sequence

A Paragraph IV certification would create litigation risk if the patent were listed and not expired. The approval date of a generic would depend on litigation timing, settlement terms, exclusivity awards, and the patent’s effective expiration date.

What patent litigation affects Duexis?

A complete litigation assessment requires current PACER, USPTO, and FDA records. The supplied claim text establishes the patent’s substantive scope but does not establish the current docket, defendants, settlement terms, or launch restrictions.

The key litigation questions are:

Whether an ANDA applicant certified Paragraph IV;
Whether the patent owner filed suit within 45 days;
Whether a 30-month stay applied;
Whether the dispute ended by judgment, dismissal, or settlement;
Whether the settlement included a generic entry date;
Whether any authorized generic or license arrangement was created; and
Whether the patent remained enforceable after prosecution-history or validity challenges.

A settlement could permit entry before patent expiration while preserving the patent’s validity and enforceability. Without the operative agreement and docket history, the commercial entry date cannot be inferred from the claims.

What licensing deals and commercial relationships are relevant?

Duexis was developed and commercialized through relationships involving Pozen and Horizon Pharma. Horizon acquired rights associated with the product and commercialized Duexis in the United States. The patent owner, NDA holder, commercial seller, and litigation plaintiff may not always be the same legal entity.

For diligence, ownership should be traced through:

USPTO assignment records;
FDA NDA ownership records;
Corporate merger and acquisition filings;
License agreements;
Securities filings; and
Litigation pleadings identifying real parties in interest.

A license may affect who can sue, who can settle a Paragraph IV dispute, and whether a generic can enter under an authorized-generic arrangement.

How does US Patent 8,067,451 compare with competing NSAID gastroprotection products?

Duexis differs from products that combine an NSAID with a proton pump inhibitor.

Product type	NSAID component	Gastroprotective component	Release concept
Duexis	Ibuprofen	Famotidine	Immediate release of both components
NSAID/PPI combination	Often naproxen or another NSAID	Esomeprazole or another PPI	Frequently delayed or enteric release
Separate coadministration	Variable NSAID	Separate H2 blocker or PPI	No single-tablet architecture

The patent excludes enteric, sustained-release, and delayed-release formulations. That limitation separates its claimed technology from many NSAID/PPI products.

What generic launch risks exist?

A generic launch would face several distinct risks:

Formulation infringement: The product may reproduce the barrier layer or equivalent architecture.
Release testing: The product may meet the claimed 60% or 75% release thresholds.
Method-of-use exposure: Labeling may retain ulcer-risk-reduction language.
Stability evidence: The generic’s impurity profile may resemble the patented limitation.
Manufacturing evidence: Process documents may show coating of the famotidine portion before compression with ibuprofen.
Regulatory delay: A Paragraph IV suit may trigger the statutory stay.
Settlement restrictions: A settlement may defer launch beyond approval.
Commercial substitution: Pharmacists may not automatically substitute a redesigned product if it lacks therapeutic equivalence or the same labeled indication.

A design-around strategy would most likely focus on the famotidine coating system, physical separation method, dosage strength, release profile, or labeling.

Key Takeaways

US Patent 8,067,451 targets the Duexis-type 800 mg ibuprofen/26.6 mg famotidine immediate-release tablet.
The central limitation is complete separation of the famotidine portion from ibuprofen by a specified barrier layer.
The patent also requires a defined famotidine impurity limit, rapid co-release, and TID administration.
Claims 1 and 10 protect the composition; claim 8 protects the three-dose treatment method.
Claims 3 and 4 create measurable release-profile limitations.
Claims 5 and 7 narrow the formulation to one containing microcrystalline cellulose.
The patent is strongest against a direct Duexis copy and weaker against a redesigned fixed-dose combination.
Generic risk depends on formulation architecture, release data, labeling, Orange Book status, Paragraph IV activity, and any settlement.
Patent expiration should be taken from the current USPTO patent-term record and FDA Orange Book entry, not inferred solely from the issue date.
The commercial patent landscape also depends on assignments, licenses, litigation outcomes, and FDA regulatory records.

Frequently Asked Questions

Does US Patent 8,067,451 cover any ibuprofen and famotidine tablet?

No. The claims require specific strengths, a separated tablet architecture, a defined barrier layer, immediate co-release, and other limitations.

Can a generic avoid the patent by using 800 mg ibuprofen and a different famotidine dose?

A different famotidine dose would create a strong non-infringement position against claims requiring 26.6 mg, although other patent claims or regulatory requirements could remain relevant.

Does the patent cover separate ibuprofen and famotidine tablets taken together?

The claims are directed to a single oral dosage tablet containing separate portions. Separate tablets would not ordinarily satisfy the claimed tablet structure.

Can a generic omit the ulcer-prevention indication?

A labeling carve-out may reduce method-of-use risk, but it does not eliminate potential infringement of composition claims. Actual labeling, marketing, prescribing, and product structure remain material.

Is famotidine protected as a new chemical entity by this patent?

No. The patent protects a combination dosage form, formulation architecture, stability profile, release behavior, and treatment regimen. It does not establish new-chemical-entity protection for famotidine.

References

U.S. Patent No. 8,067,451. (2011). Pharmaceutical composition comprising ibuprofen and famotidine. United States Patent and Trademark Office. https://patents.google.com/patent/US8067451
U.S. Food and Drug Administration. (2024a). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (2024b). Duexis prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/
U.S. Food and Drug Administration. (2024c). Approved drug products and patent and exclusivity information. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-patent-and-exclusivity-information

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Horizon	DUEXIS	famotidine; ibuprofen	TABLET;ORAL	022519-001	Apr 23, 2011		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial	Y			RELIEF OF SIGNS AND SYMPTOMS OF RHEUMATOID ARTHRITIS AND OSTEOARTHRITIS AND TO DECREASE RISK OF DEVELOPING UPPER GASTROINTESTINAL ULCERS IN PATIENTS WHO ARE TAKING IBUPROFEN FOR THOSE INDICATIONS	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	E539747	⤷ Start Trial
Australia	2006269894	⤷ Start Trial
Australia	2007275360	⤷ Start Trial
Brazil	PI0714937	⤷ Start Trial
Canada	2615496	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,067,451

Which drugs does patent 8,067,451 protect, and when does it expire?

Summary for Patent: 8,067,451