U.S. Patent 8,741,956: Claim Scope, Expiration, Litigation Risk, and Patent Landscape for Pennsaid

U.S. Patent No. 8,741,956 protects selected methods of treating knee osteoarthritis by combining a full therapeutic dose of an oral NSAID with topical diclofenac containing 40% to 50% dimethyl sulfoxide, while requiring periodic laboratory evaluations or instructions to conduct them. The patent is a method-of-use patent, not a broad composition patent. Its commercial relevance is concentrated on products and labeling that combine oral NSAID therapy with 1.5% diclofenac sodium topical solution, including Pennsaid-type formulations.

The strongest commercial coverage is directed to the combination of:

Oral NSAID therapy.
Topical diclofenac applied to the knee.
Osteoarthritis treatment.
A topical formulation containing 40% to 50% w/w DMSO.
Periodic laboratory monitoring or written instructions requiring monitoring.

The narrowest claims focus on about 45.5% DMSO, 1.5% diclofenac sodium, and the excipient combination of ethanol, propylene glycol, glycerine, and water. The patent does not cover every topical diclofenac product or every use of Pennsaid independently.

What does U.S. Patent 8,741,956 cover?

The independent claims cover three related implementation models.

Claim group	Core requirement	Monitoring requirement	Written instructions
Claims 1-9	Oral NSAID plus topical diclofenac for knee osteoarthritis	Patient must be informed to conduct periodic laboratory evaluations	Optional, then required by claims 3-4
Claims 10-17	Oral NSAID plus topical diclofenac for knee osteoarthritis	Patient must be informed and periodic evaluations must be conducted	Optional, then required by claims 11-12
Claims 18-23	Oral NSAID plus topical diclofenac for knee osteoarthritis	Evaluations must be conducted	Administration, application, and monitoring must follow written instructions

Claim 1 is the broadest independent claim in the first group. Claim 10 adds the affirmative requirement that periodic laboratory evaluations actually be conducted. Claim 18 requires performance according to written instructions, making it particularly relevant to an FDA-approved product label or package insert.

The central formulation limitation is:

A therapeutically effective amount of a diclofenac salt and 40% to 50% w/w dimethyl sulfoxide.

The claim set also includes the narrower limitation of approximately 45.5% w/w DMSO, which corresponds to the well-known Pennsaid 1.5% topical diclofenac formulation. The FDA-approved Pennsaid labeling identifies diclofenac sodium 1.5% in a vehicle containing DMSO and other excipients used to facilitate topical delivery [2].

How do the independent claims differ?

Claim 1: Combination treatment plus patient notification

Claim 1 requires the patient to receive:

A therapeutically effective oral NSAID dose;
Topical diclofenac applied to the knee;
Treatment of osteoarthritis;
A topical preparation containing 40% to 50% DMSO; and
Information directing periodic laboratory evaluations.

The claim defines the oral NSAID dose as the amount required to achieve a therapeutic effect without topical diclofenac. This limitation is important. It appears designed to prevent an accused infringer from arguing that the oral NSAID was merely incidental or subtherapeutic.

Claim 1 does not expressly require that the patient complete the laboratory testing. Notification is sufficient for the independent claim. Claims 2 through 4 narrow the claim by adding actual testing or specific written instructions.

Claim 10: Combination treatment plus actual testing

Claim 10 includes the same combination therapy and notification requirements but expressly requires conducting periodic laboratory evaluations.

This claim has a narrower infringement pathway than claim 1 because proof of completed laboratory monitoring is required. It may be more difficult to establish through product labeling alone unless actual clinical practice follows the label.

Claim 18: Written protocol implementation

Claim 18 requires that administering the oral NSAID, applying topical diclofenac, and conducting laboratory evaluations occur in accordance with written instructions.

This claim is structurally significant because the written instructions can be incorporated into a product insert. Claims 19 through 23 then narrow the claim to a product insert, the 45.5% DMSO formulation, specified excipients, specified diclofenac salts, or 1.5% diclofenac sodium.

What formulations are protected by U.S. Patent 8,741,956?

The formulation limitations are layered rather than independent.

Formulation limitation	Claim coverage
Diclofenac salt with 40% to 50% DMSO	Claims 1, 10, and 18
Approximately 45.5% w/w DMSO	Claims 5, 13, and 20
Ethanol, propylene glycol, glycerine, and water	Claims 6, 14, and 21
Sodium, potassium, diethylamine, or epolamine diclofenac salt	Claims 7, 15, and 22
1.5% w/w diclofenac sodium	Claims 8, 16, and 23

The patent does not require every listed excipient unless the relevant dependent claim is asserted. A product containing diclofenac sodium and 45.5% DMSO may fall within claims 5, 13, or 20 only if the other method limitations are also satisfied.

The claim language is directed to weight percentage. A formulation using 45.5% DMSO on a different measurement basis, such as volume percentage, would not automatically satisfy the limitation. Manufacturing records, batch formulas, certificates of analysis, and product specifications would be relevant to infringement analysis.

How does the patent protect Pennsaid-type treatment?

Pennsaid-type treatment is the most obvious commercial embodiment because the approved product is a topical diclofenac sodium solution indicated for osteoarthritis pain in the knee. The formulation uses 1.5% diclofenac sodium and approximately 45.5% DMSO, with ethanol, propylene glycol, glycerin, and water identified in the product labeling [2].

The patent does not claim:

Topical diclofenac alone;
Oral NSAID therapy alone;
All topical NSAID formulations;
Osteoarthritis treatment without the DMSO range;
Diclofenac gel formulations that do not contain the claimed DMSO concentration; or
A patient taking an oral NSAID without topical diclofenac.

The commercial risk arises when a product label, prescriber protocol, clinical trial, or patient-management program instructs use of topical diclofenac together with an oral NSAID for knee osteoarthritis and requires laboratory monitoring.

When does U.S. Patent 8,741,956 lose exclusivity?

The patent was granted on June 3, 2014. Its statutory term is approximately 20 years from the applicable earliest nonprovisional filing date and reaches approximately February 2027, subject to any patent-term adjustment or other official term calculation recorded by the USPTO [1].

Event	Date
Earliest priority period associated with the patent family	February 2006
U.S. patent grant	June 3, 2014
Approximate statutory expiration	February 2027
Post-expiration position	Claims generally cease to block conduct occurring after expiration

Patent expiration does not eliminate other patents that may protect the same product. A generic or follow-on developer must review the entire relevant patent family, Orange Book listings, regulatory exclusivity, and any separate formulation, manufacturing, or use patents.

The patent is a small-molecule method patent. It does not create biosimilar exclusivity and is not subject to the biologics patent framework under section 351(k) of the Public Health Service Act.

What is the Orange Book status of U.S. Patent 8,741,956?

The FDA Orange Book determines whether a patent is listed for an approved drug product and whether it is identified as a drug substance, drug product, or method-of-use patent [3]. The claim language strongly resembles a method-of-use listing relevant to an approved diclofenac topical product.

An Orange Book listing does not establish validity or infringement. It can, however, create an ANDA certification issue. A generic applicant may need to submit a Paragraph IV certification if it seeks approval before patent expiration and contends that the listed patent is invalid, unenforceable, or not infringed.

For a product corresponding to Pennsaid, the relevant regulatory questions are:

Whether U.S. Patent 8,741,956 remains listed for the applicable NDA.
Which approved indication or labeling section is associated with the listing.
Whether the generic seeks the same combination-use indication.
Whether a section viii statement can carve out the patented method.
Whether the proposed labeling still induces the patented combination use.

A section viii carve-out may reduce risk only if the proposed labeling omits the patented method and does not otherwise encourage the combination of oral NSAID therapy, topical diclofenac, and monitoring.

Which Paragraph IV challenges could target this patent?

A Paragraph IV challenge would likely focus on claim construction, anticipation, obviousness, written description, enablement, and induced infringement.

Anticipation and obviousness

Potential prior-art categories include:

Earlier Pennsaid or topical diclofenac publications;
Diclofenac formulations containing DMSO;
Osteoarthritis treatment protocols using topical and oral NSAIDs;
NSAID safety guidance requiring renal, hepatic, hematologic, or other laboratory monitoring;
Product inserts or clinical studies describing combined NSAID treatment.

The combination of known components may create an obviousness argument. The patent holder would likely respond that the claimed combination links a specific topical formulation, a full-dose oral NSAID regimen, knee osteoarthritis treatment, and periodic laboratory monitoring in a defined therapeutic protocol.

The 45.5% DMSO and 1.5% diclofenac sodium limitations may be easier to map to an approved product but may also be vulnerable if the exact formulation and use protocol were publicly disclosed before the relevant filing date.

Indefiniteness and claim construction

Several terms may generate disputes:

“Along with” may require concurrent or overlapping treatment, but the claims do not specify a precise time interval.
“Periodic laboratory evaluations” does not define the frequency, test type, or duration.
“Therapeutically effective amount” is functional and depends on patient response.
“The amount required to achieve a therapeutic effect in the absence of applying a topical diclofenac preparation” creates a comparator that may require clinical or pharmacological evidence.
“Written instructions” is broad, while claims 4, 12, and 19 specify a product insert.

The monitoring requirement may be the principal limitation separating the claimed methods from ordinary combination therapy.

Written description and enablement

A challenger may argue that the specification does not adequately support every listed oral NSAID, every recited diclofenac salt, and every combination of formulation and monitoring requirements. Claim 9 and claim 17 cover a long list of oral NSAIDs, including COX-2 selective agents, diclofenac, ibuprofen, naproxen, celecoxib, and other drugs.

The patent holder would argue that the claims describe a genus supported by common NSAID pharmacology and a disclosed therapeutic rationale. The outcome would depend on the specification, examples, filing-date disclosure, and the governing written-description standard.

What patent litigation affects U.S. Patent 8,741,956?

The supplied claim text does not identify a litigation docket, asserted claims, settlement, or Paragraph IV notice. A reliable litigation conclusion cannot be drawn from the claims alone.

For business diligence, the relevant litigation records are:

Hatch-Waxman cases filed under 21 U.S.C. § 355(j);
District court complaints involving Pennsaid or a therapeutically equivalent topical diclofenac product;
PTAB inter partes review or post-grant review petitions;
Federal Circuit decisions concerning claim construction or validity;
Settlement agreements involving delayed generic entry or licensing;
FDA correspondence concerning patent listing or labeling carve-outs.

The existence of an Orange Book listing would increase procedural exposure but would not establish that the patent is enforceable. Conversely, the absence of a public case would not prove that no Paragraph IV notice or confidential settlement exists.

How strong is the patent estate?

The strength of U.S. Patent 8,741,956 is mixed.

Factor	Assessment
Product mapping	Strong for a Pennsaid 1.5% formulation with approximately 45.5% DMSO
Claim breadth	Moderate to narrow because the claims require a specific treatment combination
Formulation protection	Moderate; the core formulation is closely tied to known product characteristics
Method-of-use protection	Potentially meaningful if the label encourages oral NSAID combination use and monitoring
Monitoring limitation	Creates proof challenges but may distinguish prior art
Generic design-around potential	Significant if the generic omits combination-use instructions or monitoring language
Biosimilar relevance	None; diclofenac is a small molecule
Geographic coverage	U.S. only
Manufacturing barrier	Limited unless a separate composition or process patent applies
Remaining term	Approximately through February 2027

The patent’s strongest enforcement theory is likely induced infringement based on product labeling or written clinical instructions. A manufacturer may face risk even if physicians and patients perform the claimed steps, provided the manufacturer’s labeling intentionally encourages the full combination regimen and the remaining legal requirements for inducement are met.

Direct method infringement would generally depend on the conduct of the treating physician, patient, or healthcare provider. That creates practical enforcement limits. Induced infringement can shift attention to the manufacturer’s label, promotional materials, dosing instructions, and safety-monitoring recommendations.

What generic launch scenarios exist?

Scenario 1: Same formulation, same combination-use labeling

This presents the highest risk. A generic matching 1.5% diclofenac sodium and approximately 45.5% DMSO, with labeling that instructs use alongside an oral NSAID for knee osteoarthritis and periodic laboratory evaluations, would closely track the claims.

Scenario 2: Same formulation with carved-out labeling

A generic may reduce risk by omitting the patented combination-use instructions. The outcome would depend on whether the remaining labeling, warnings, or promotional conduct still encourages the claimed method.

Scenario 3: Different DMSO concentration

A product outside the 40% to 50% w/w range may avoid the independent formulation limitation. The developer would still need to assess separate composition patents, equivalence theories, and regulatory requirements.

Scenario 4: Different diclofenac salt

The independent claims require a diclofenac salt but do not limit claims 1, 10, and 18 to diclofenac sodium. Claims 7, 15, and 22 expressly list sodium, potassium, diethylamine, and epolamine salts. A different salt may avoid the 1.5% diclofenac sodium dependent claims while remaining within the broader independent claims.

Scenario 5: No oral NSAID combination

A topical-only product does not satisfy the oral NSAID limitation. This is the clearest design-around route under the supplied claims.

What licensing or settlement implications exist?

No licensing deal or settlement agreement can be established from the claim text. Commercial diligence should distinguish between:

A license to the topical diclofenac formulation;
A license to the combination-use method;
A supply or commercialization agreement;
A settlement allowing entry after patent expiration;
A settlement permitting an earlier launch with restricted labeling; and
A patent assignment or ownership change.

A license covering the product formulation would not necessarily authorize the claimed combination treatment method. The patent’s method claims should be separately addressed in transaction documents, particularly where the licensee will control labeling, medical information, promotional materials, or postmarketing safety instructions.

Key Takeaways

U.S. Patent 8,741,956 is a method-of-use patent centered on combined oral NSAID and topical diclofenac therapy for knee osteoarthritis.
The topical preparation must contain 40% to 50% w/w DMSO in the independent claims.
The most commercially relevant embodiment is 1.5% diclofenac sodium with approximately 45.5% DMSO.
Claims 1-9 focus on informing the patient about laboratory evaluations.
Claims 10-17 require that laboratory evaluations actually be conducted.
Claims 18-23 require administration, application, and monitoring under written instructions, including a product insert in claim 19.
The patent does not broadly protect topical diclofenac, Pennsaid, or all osteoarthritis treatment.
Labeling and promotional materials are central to induced-infringement risk.
A generic may reduce exposure through a labeling carve-out, a noncovered DMSO concentration, a different formulation, or omission of oral NSAID combination use.
The patent’s statutory term reaches approximately February 2027, subject to the official USPTO term calculation.
The patent is relevant to ANDA Paragraph IV strategy but has no biosimilar relevance.

FAQs About U.S. Patent 8,741,956

Does U.S. Patent 8,741,956 cover Pennsaid by itself?

No. The claims require a treatment method that combines topical diclofenac with an oral NSAID and includes laboratory-monitoring requirements or written instructions, depending on the claim.

Can a generic avoid the patent by using diclofenac gel?

Potentially. A diclofenac gel without 40% to 50% w/w DMSO would not satisfy the central formulation limitation in the supplied claims. Other patents and regulatory requirements would still require separate analysis.

Does claim 1 require actual laboratory testing?

No. Claim 1 requires informing the patient to conduct periodic laboratory evaluations. Actual testing is expressly required by claim 10 and claim 18.

Is 45.5% DMSO required in every claim?

No. Claims 1, 10, and 18 require the broader 40% to 50% range. The approximately 45.5% limitation appears in dependent claims 5, 13, and 20.

Does the patent cover a patient using ibuprofen with topical diclofenac?

Potentially, if the other limitations are met. Ibuprofen is expressly listed in claims 9 and 17, but the regimen must also involve knee osteoarthritis, the claimed topical diclofenac formulation, and the applicable monitoring or written-instruction requirements.

References

United States Patent and Trademark Office. (2014). U.S. Patent No. 8,741,956, methods for treating osteoarthritis. U.S. Department of Commerce.
U.S. Food and Drug Administration. (n.d.). Pennsaid- diclofenac sodium topical solution prescribing information. DailyMed.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, Orange Book. FDA.

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	PENNSAID	diclofenac sodium	SOLUTION;TOPICAL	204623-001	Jan 16, 2014		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial				COMBINATION USE OF TOPICAL DICLOFENAC ON THE KNEE AND ADMINISTRATION OF AN ORAL NSAID.	⤷ Start Trial
Nuvo Pharms Inc	PENNSAID	diclofenac sodium	SOLUTION;TOPICAL	020947-001	Nov 4, 2009		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial				COMBINATION USE OF TOPICAL DICLOFENAC ON THE KNEE AND ADMINISTRATION OF AN ORAL NSAID.	⤷ 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

Details for Patent: 8,741,956

Which drugs does patent 8,741,956 protect, and when does it expire?

Summary for Patent: 8,741,956