US Patent 9,066,913: Diclofenac Sodium 2% Topical Formulation, Claims, Exclusivity and Patent Landscape

US Patent No. 9,066,913 protects a specific diclofenac sodium topical solution associated with PENNSAID 2%. Its strongest protection is directed to the formulation itself: 2% diclofenac sodium, approximately 40%-50% DMSO, 23%-29% ethanol, 10%-12% propylene glycol, hydroxypropyl cellulose, water, and viscosity of 500-5,000 centipoise. The patent also covers the formulation's pH, stability profile, narrower excipient concentrations, and twice-daily treatment of knee osteoarthritis pain. [1]

The patent does not broadly cover all diclofenac topical products, all DMSO-containing formulations, or all methods of treating osteoarthritis.

What does US Patent 9,066,913 protect?

US 9,066,913 contains two principal claim categories:

Composition claims covering a diclofenac sodium topical formulation.
Method-of-use claims covering twice-daily administration to a knee for osteoarthritis pain.

The independent formulation claim, claim 1, requires every listed element:

Claim element	Required scope
Diclofenac sodium	2% w/w
DMSO	About 40%-50% w/w
Ethanol	23%-29% w/w
Propylene glycol	10%-12% w/w
Hydroxypropyl cellulose	Required, but no amount in claim 1
Water	Quantity sufficient to reach 100% w/w
Viscosity	500-5,000 centipoise

A formulation that omits hydroxypropyl cellulose, uses diclofenac potassium rather than diclofenac sodium, falls outside the recited solvent ranges, or has viscosity outside the claimed range would not literally meet claim 1.

The patent's composition coverage is therefore relatively narrow but commercially relevant. A competing product can avoid literal infringement by changing one or more critical formulation variables, although the doctrine of equivalents and other patent claims must be assessed separately.

How do the dependent formulation claims narrow the patent?

Claims 2, 3, 4, and 8-10 add specific technical limitations to claim 1.

Claim	Additional limitation
2	pH of 6-10
3	Propylene glycol at 11.2% w/w
4	Less than 0.1% impurity A after six months at 25°C and 60% relative humidity
8	DMSO at 45.5% w/w
9	DMSO at 45.5% w/w and hydroxypropyl cellulose at 2.5% w/w
10	Hydroxypropyl cellulose at 2.5% w/w

Claims 3, 8, 9, and 10 align closely with the commercial formulation associated with PENNSAID 2%. The combination of 45.5% DMSO, 11.2% propylene glycol, 2.5% hydroxypropyl cellulose, and 2% diclofenac sodium is materially narrower than the broad ranges in claim 1.

Claim 4 is a stability limitation. It requires performance after a defined storage period and condition. A party assessing infringement would need reliable stability data, analytical methods, impurity identification, and testing of representative commercial batches. The claim is not satisfied merely because a formulation has the same ingredients.

What is the scope of the method-of-use claims?

Claims 5-7, 11, and 12 cover treatment of osteoarthritis pain in a knee using the claimed formulation.

Claim	Method limitation
5	Administer the claim 1 formulation to a knee twice daily
6	Administer 2 mL to the knee twice daily
7	Administer 40 mg diclofenac sodium to the knee twice daily
11	Administer the claim 8 formulation to the knee twice daily
12	Administer the claim 9 formulation to the knee twice daily

The method claims are narrower than a general claim to treating pain. They require:

Osteoarthritis-related pain;
A knee as the treatment site;
The patented topical formulation; and
Twice-daily administration.

The claims do not expressly cover treatment of the hip, shoulder, hand, ankle, or generalized musculoskeletal pain. They also do not cover once-daily use or oral administration.

The 2 mL and 40 mg limitations in claims 6 and 7 correspond to the labeled dosing framework for PENNSAID 2%, which delivers 40 mg of diclofenac sodium per knee with twice-daily dosing. [2]

What product is associated with US 9,066,913?

US 9,066,913 is associated with PENNSAID 2%, a diclofenac sodium topical solution approved by the FDA for the treatment of osteoarthritis pain of the knee. The approved product uses a DMSO-based vehicle and is applied twice daily. [2]

The commercial formulation described in the patent and product labeling includes the following approximate composition:

Component	Approximate concentration
Diclofenac sodium	2% w/w
DMSO	45.5% w/w
Ethanol	Within the patented 23%-29% range
Propylene glycol	11.2% w/w
Hydroxypropyl cellulose	2.5% w/w
Water and other formulation components	Balance

The product's formulation and dosing profile closely track the narrower limitations in claims 3, 8, 9, and 10.

When does US Patent 9,066,913 lose exclusivity?

The patent issued on June 23, 2015. Its earliest claimed priority date is December 18, 2009. On the standard US patent-term calculation, the nominal expiration date is expected to be December 18, 2029, subject to any applicable patent-term adjustment, terminal disclaimer, or regulatory patent-term extension reflected in official records. [1]

Event	Date
Earliest priority date	December 18, 2009
Patent grant	June 23, 2015
Expected nominal expiration	December 18, 2029
FDA approval of PENNSAID 2%	January 16, 2014

Patent expiration does not automatically eliminate all market barriers. Other patents, regulatory exclusivity, approved-use restrictions, product-specific listings, settlement agreements, and manufacturing patents can affect generic entry.

What is the Orange Book status of US 9,066,913?

PENNSAID 2% is an FDA-approved prescription drug, and patents associated with the product may be listed in the FDA's Approved Drug Products with Therapeutic Equivalence Evaluations, commonly called the Orange Book. The relevant Orange Book analysis must distinguish between:

Patents listed against the reference product;
Use codes associated with method-of-use patents;
Expired patents;
Unexpired patents;
Patents challenged through Paragraph IV certifications; and
Patents that remain relevant but are not listed for a particular approved product.

US 9,066,913 is significant because its claims track both the formulation and approved knee-osteoarthritis use. A generic applicant seeking approval for the same 2% diclofenac sodium topical solution could face formulation-patent and method-of-use issues depending on the patent listings and the applicant's labeling strategy.

An ANDA applicant can certify under Paragraph IV that a listed patent is invalid, unenforceable, or will not be infringed. The reference-product sponsor may then bring patent litigation within the statutory period, potentially triggering a 30-month stay of approval under the Hatch-Waxman Act. [3]

Which companies have challenged or competed against PENNSAID 2%?

The competitive field includes manufacturers of generic diclofenac products, branded diclofenac topical products, and alternative topical nonsteroidal anti-inflammatory drugs.

Product or category	Active ingredient	Formulation	Relevance to US 9,066,913
PENNSAID 2%	Diclofenac sodium	DMSO-based topical solution	Direct commercial product associated with the patent
PENNSAID 1.5%	Diclofenac sodium	DMSO-based topical solution	Related product, but not identical to the claimed 2% formulation
Voltaren Arthritis Pain	Diclofenac sodium	1% topical gel	Different concentration, vehicle, and dosage form
Generic diclofenac sodium gel	Diclofenac sodium	Usually 1% gel	Generally outside the literal formulation limitations
Solaraze	Diclofenac sodium	3% topical gel	Different concentration and indication
Generic diclofenac topical solution	Diclofenac sodium	Product-specific	Potentially direct competitor if it matches the claimed formulation

Public patent disputes involving PENNSAID products have included challenges by generic-drug companies to patents covering diclofenac topical formulations and related methods. The litigation risk depends on the specific ANDA, proposed product composition, proposed labeling, patent certifications, and any settlement terms. Patent litigation involving related PENNSAID patents does not automatically determine the validity or enforceability of US 9,066,913.

How strong is the patent estate for PENNSAID 2%?

US 9,066,913 is strongest against a product that reproduces the commercial formulation. The most important infringement combination is:

Diclofenac sodium at 2%;
DMSO at approximately 45.5%;
Propylene glycol at approximately 11.2%;
Hydroxypropyl cellulose at approximately 2.5%;
Ethanol within the claimed range;
Viscosity between 500 and 5,000 centipoise; and
Twice-daily knee administration.

The patent is weaker against products that materially redesign the vehicle. A generic developer could attempt to use:

A non-DMSO solvent system;
DMSO outside the claimed range;
A different cellulose derivative;
A lower or higher diclofenac concentration;
A gel rather than a solution;
A different viscosity profile; or
A label that omits the patented osteoarthritis-knee use, subject to induced-infringement and labeling analysis.

The patent's technical vulnerability would likely center on written description, enablement, obviousness, anticipation, claim construction, and whether the stability limitation in claim 4 is sufficiently definite and reproducible. The commercial strength comes from the narrow claims' close correspondence to the marketed product.

What manufacturing and intellectual-property barriers exist?

The formulation requires more than simply blending diclofenac sodium with a solvent. Relevant barriers include:

Maintaining diclofenac sodium solubility in a high-DMSO vehicle;
Controlling viscosity within the claimed range;
Managing ethanol and water levels during manufacturing;
Achieving uniform hydroxypropyl cellulose dispersion;
Limiting impurity A formation;
Demonstrating six-month stability under the claimed condition;
Preserving dose uniformity in the delivery container; and
Matching the reference product's performance for ANDA purposes.

These process controls can create practical barriers even where a competing formulation avoids literal infringement. They do not independently establish patent infringement unless covered by an asserted claim.

Does biosimilar risk apply to this patent?

No. Biosimilar risk is not the relevant pathway because diclofenac sodium is a small-molecule active pharmaceutical ingredient. Competition proceeds primarily through the ANDA pathway, not the abbreviated biologics license application pathway. The relevant regulatory issues are pharmaceutical equivalence, bioequivalence, product labeling, inactive ingredients, device performance where applicable, and patent certifications. [3]

What generic-entry scenarios exist?

Three principal scenarios apply:

Direct formulation match: A generic reproduces the claimed composition and seeks approval for the same use. This creates the highest infringement exposure.
Formulation design-around: A generic changes the solvent, concentration, polymer, or viscosity. This may reduce literal infringement risk but requires pharmaceutical-development and bioequivalence support.
Carve-out or restricted labeling: A generic omits a patented method of use from its labeling. The effectiveness of this strategy depends on the final label and actual marketing conduct.

The expected nominal expiration in December 2029 creates a long patent horizon from the 2014 approval date. Earlier entry would depend on successful invalidity or noninfringement positions, settlement arrangements, authorized-generic activity, or other statutory mechanisms.

How does US 9,066,913 compare with competing diclofenac patents?

The patent differs from common diclofenac gel patents in three ways:

It protects a liquid DMSO-based system rather than a conventional aqueous or carbomer gel.
It uses a 2% diclofenac sodium concentration.
It claims twice-daily application to knee osteoarthritis pain with a defined dose.

Voltaren 1% gel and Solaraze 3% gel use different dosage forms, concentrations, and product architectures. Their patents and regulatory protections must be analyzed separately. A competitor's diclofenac product can be therapeutically similar while remaining outside the literal composition of US 9,066,913.

Key Takeaways

US 9,066,913 is a formulation and method-of-use patent associated with PENNSAID 2%.
Claim 1 requires 2% diclofenac sodium, 40%-50% DMSO, 23%-29% ethanol, 10%-12% propylene glycol, hydroxypropyl cellulose, water, and 500-5,000 cP viscosity.
Claims 8-10 narrow the protection around 45.5% DMSO and 2.5% hydroxypropyl cellulose.
Claims 5-7, 11, and 12 cover twice-daily administration to a knee for osteoarthritis pain.
The expected nominal patent expiration is December 18, 2029, subject to official term adjustments and related legal records.
Direct generic substitution using the same formulation presents the highest infringement risk.
Biosimilar competition is not relevant; ANDA-based generic competition is the applicable pathway.
The principal design-around options involve changing the solvent system, polymer, concentration, viscosity, or labeling.

FAQs

Is US 9,066,913 a patent on all diclofenac topical products?

No. It is limited to a defined diclofenac sodium formulation and specified knee-osteoarthritis treatment methods.

Does a diclofenac 1% gel infringe US 9,066,913?

Not literally on the stated claims if it lacks the claimed 2% concentration, DMSO range, ethanol range, propylene glycol range, hydroxypropyl cellulose, and viscosity. Other patents may still apply.

Does claim 4 require six months of testing before infringement can be assessed?

Claim 4 includes a six-month stability performance limitation. Testing and analytical evidence would generally be relevant to determining whether a competing formulation meets that limitation.

Can a generic obtain approval by removing knee osteoarthritis from its label?

A labeling carve-out may reduce method-of-use exposure, but it does not eliminate formulation-patent risk and does not resolve liability based on actual marketing conduct.

Is the 2029 expiration date the same as guaranteed generic launch timing?

No. Generic launch timing can be earlier through litigation success or settlement, or later because of other patents, regulatory barriers, manufacturing constraints, or commercial decisions.

References

United States Patent and Trademark Office. (2015). US Patent No. 9,066,913, topical formulations and methods of use.
U.S. Food and Drug Administration. (2014). PENNSAID 2% diclofenac sodium topical solution prescribing information.
U.S. Food and Drug Administration. (2023). Approved drug products with therapeutic equivalence evaluations. Orange Book.

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	9,066,913	⤷ Start Trial	Y			USE OF TOPICAL DICLOFENAC FOR TREATING PAIN	⤷ 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
Australia	2007311019	⤷ Start Trial
Brazil	PI0717769	⤷ Start Trial
Canada	2666398	⤷ Start Trial
China	101588791	⤷ Start Trial
China	104606126	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 9,066,913

Which drugs does patent 9,066,913 protect, and when does it expire?

Summary for Patent: 9,066,913