Details for Patent: 8,679,544

Which drugs does patent 8,679,544 protect, and when does it expire?

Patent 8,679,544 protects ZORVOLEX and is included in one NDA.

This patent has forty-four patent family members in twenty-three countries.

Summary for Patent: 8,679,544

Title:	Formulation of diclofenac
Abstract:	The present invention relates to methods for producing particles of diclofenac using dry milling processes as well as compositions comprising diclofenac, medicaments produced using diclofenac in particulate form and/or compositions, and to methods of treatment of an animal, including man, using a therapeutically effective amount of diclofenac administered by way of said medicaments.
Inventor(s):	Aaron Dodd, Felix Meiser, Marck Norret, Adrian Russell, H William Bosch
Assignee:	Iceutica Pty Ltd
Application Number:	US13/750,869
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 8,679,544
Patent Claim Types: see list of patent claims	Use; Composition; Formulation; Dosage form;

US Patent 8,679,544: Diclofenac Nanoparticle Claims, Scope, Expiration and Patent Landscape

US Patent 8,679,544 protects specific 18 mg and 35 mg oral diclofenac acid unit doses that combine submicron diclofenac particles, lactose monohydrate, sodium lauryl sulfate and defined dissolution performance. The patent is formulation- and performance-focused rather than a broad claim to diclofenac itself.

Its strongest commercial relevance is to low-dose, immediate-release diclofenac capsules associated with the Zorvolex product platform. A competing product must avoid the claimed particle-size range, excipient combination, dose, dissolution profile, or dependent formulation limitations to reduce literal infringement risk. A formulation that uses diclofenac potassium, a different dose, a different surfactant, or materially different dissolution performance may fall outside the literal scope, although doctrine-of-equivalents and other patent claims remain relevant.

What does US Patent 8,679,544 protect?

US 8,679,544 contains two principal independent claims:

Independent claim	Protected dose	Core formulation requirements	Dissolution threshold
Claim 1	18 mg diclofenac acid	Lactose monohydrate; sodium lauryl sulfate; diclofenac median particle size greater than 25 nm and less than 500 nm	At least 91% released by 45 minutes
Claim 6	35 mg diclofenac acid	Lactose monohydrate; sodium lauryl sulfate; diclofenac median particle size greater than 25 nm and less than 500 nm	At least 82% released by 45 minutes

Both claims require testing under a specific dissolution protocol:

• USP Apparatus I, basket method
• 100 rpm
• 37°C
• 900 mL medium
• 0.05% sodium lauryl sulfate
• Citric acid buffer at pH 5.75
• Diclofenac release measured by weight percentage

The claims are cumulative. An accused product must satisfy every limitation of the relevant independent claim and any asserted dependent claim.

The patent does not claim all diclofenac capsules, all immediate-release diclofenac products, or all nanoparticulate diclofenac formulations. It claims a defined intersection of:

1. Diclofenac acid rather than an unrestricted diclofenac salt formulation.
2. An 18 mg or 35 mg unit dose.
3. A narrow submicron particle-size range.
4. Lactose monohydrate and sodium lauryl sulfate.
5. A specified dissolution result under a defined laboratory method.

How broad are the US 8,679,544 claims?

The independent claims are narrower than they appear because the composition and performance limitations operate together.

Dose limitation

Claim 1 is limited to a unit dose containing 18 mg of diclofenac acid. Claim 6 is limited to 35 mg. A 25 mg or 50 mg product would not literally satisfy either independent claim, even if it used the same excipients and particle size.

The claims use the phrase “containing 18 mg” and “containing 35 mg.” The commercial and litigation significance depends on whether the claim is construed as requiring exactly that amount or a pharmaceutically acceptable manufacturing tolerance around the stated amount. In routine pharmaceutical litigation, assay tolerances do not normally create a practical design-around where the labeled strength is 18 mg or 35 mg.

Active ingredient limitation

The claims specify diclofenac acid. A formulation using diclofenac potassium, diclofenac sodium, or another salt may avoid literal infringement of this patent if the accused product does not contain the claimed diclofenac acid particles. That design-around does not eliminate exposure under separate diclofenac salt, formulation, method-of-use or manufacturing patents.

Particle-size limitation

The median particle size must be:

• Greater than 25 nm; and
• Less than 500 nm;

with the measurement made on a volume-average basis.

This is a central limitation. A formulation with a median particle size of 500 nm or more is outside the literal upper-bound limitation. A formulation with a median of 25 nm or less is outside the literal lower-bound limitation.

The measurement method is commercially important. Particle-size results can vary depending on dispersion medium, agglomeration control, sonication, refractive-index assumptions, instrument type and data-processing settings. A Paragraph IV certification or invalidity challenge would likely focus on claim construction and reproducibility of “median particle size on a volume average basis.”

Excipient limitation

The independent claims require both lactose monohydrate and sodium lauryl sulfate. Removing either excipient is a straightforward literal design-around. Substituting lactose anhydrous, mannitol, microcrystalline cellulose or another filler may also avoid the exact limitation, subject to the remaining patent estate.

Sodium lauryl sulfate has a dual role in the claims. It is required as a formulation component and is also present in the dissolution medium. This creates a potential evidentiary issue: the applicant can argue that the claimed surfactant contributes to wetting and release, while an accused party may challenge whether the claimed dissolution result is attributable to the formulation rather than the test medium.

Dissolution limitation

The release threshold is a substantive limitation, not merely an example of product quality.

For claim 1, the 18 mg product must release at least 91% by 45 minutes. For claim 6, the 35 mg product must release at least 82% by 45 minutes. A product containing the required ingredients and particle size may still avoid the independent claim if it fails the specified dissolution threshold.

The dependent claims impose faster or higher release:

Claims	Dose	Added dissolution requirement
2	18 mg	At least 91% by 30 minutes
3	18 mg	At least 91% by 15 minutes
4	18 mg	At least 94% by 45 minutes
5	18 mg	At least 94% by 30 minutes
7	35 mg	At least 82% by 30 minutes
8	35 mg	At least 82% by 15 minutes
9	35 mg	At least 95% by 45 minutes
10	35 mg	At least 95% by 30 minutes

Claims 3, 5, 8 and 10 are narrower than the independent claims because they require accelerated or higher dissolution. A product that meets claim 1 but releases only 91% at 45 minutes would not meet those higher-performance dependent claims.

What formulations are protected by US 8,679,544?

Claims 11 through 18 narrow the protected product to capsule and excipient configurations.

Claims	Additional limitation
11-12	Hard gelatin capsule
13-14	Binder, lubricant and disintegrant
15-16	Microcrystalline cellulose, croscarmellose sodium and sodium stearyl fumarate
17-18	D(90) particle-size limit below 1,700, 1,800, 1,900 or 2,000 nm

Claims 15 and 16 are commercially significant because they identify a conventional capsule excipient system:

• Microcrystalline cellulose as a filler or binder component
• Croscarmellose sodium as disintegrant
• Sodium stearyl fumarate as lubricant

A generic manufacturer using the same excipient trio, the claimed diclofenac particle size, and the relevant 18 mg or 35 mg strength would face a stronger infringement case than a manufacturer using only lactose monohydrate and sodium lauryl sulfate.

The D(90) limitations extend protection beyond the median particle size. A formulation could have a median below 500 nm but still fail a D(90) limitation if its coarse-particle tail exceeds the applicable threshold. These claims are vulnerable to testing variability because D(90) is sensitive to a relatively small population of large particles or agglomerates.

Do claims 19 through 24 protect pharmacokinetic and pain-relief performance?

Claims 19 and 20 require a Tmax below one of several stated time points, ranging from less than five hours to less than 30 minutes. Claim 19 applies to the 18 mg formulation, and claim 20 applies to the 35 mg formulation.

Claims 21 through 24 compare pain-relief timing with 400 mg celecoxib:

• Claims 21 and 22 concern time to first perceptible pain relief.
• Claims 23 and 24 concern time to peak pain relief.

These claims are difficult to enforce in ordinary product litigation because they require human clinical evidence and comparator-specific proof. The claimant would need to establish the relevant pain-relief endpoint, patient population, dosing conditions, statistical methodology and comparison against 400 mg celecoxib.

The claims also present construction issues. “First perceptible pain relief” and “time to peak pain relief” may require interpretation based on the specification and clinical protocol. A generic manufacturer may avoid these limitations by producing a formulation that does not meet the recited pharmacokinetic or clinical endpoint, although the independent composition claims remain the primary risk.

When does US Patent 8,679,544 lose exclusivity?

The patent issued on March 25, 2014. Its statutory expiration depends on the effective filing date of the relevant nonprovisional application, the earliest priority claim in the family, any patent-term adjustment, and any terminal disclaimer. The issue date alone does not establish the expiration date.

For a US pharmaceutical patent in this family, the practical term analysis should include:

Term item	Relevance
Earliest effective nonprovisional filing date	Establishes the basic 20-year patent term
Patent-term adjustment	Can extend the term for USPTO examination delay
Patent-term extension under 35 U.S.C. §156	May apply if the patent was selected for extension based on regulatory review
Terminal disclaimer	Can shorten the term if the patent is tied to another patent
Patent maintenance fees	Failure to pay can cause expiration before the nominal term

The patent should be assessed through the USPTO Patent Center and the USPTO maintenance-fee record before relying on a precise expiration date. A commercial launch analysis should also separate this patent’s term from the expiration dates of other Zorvolex-related patents and regulatory exclusivities.

What is the FDA and Orange Book status of the protected product?

Zorvolex is an FDA-approved diclofenac capsule product marketed in 18 mg and 35 mg strengths. FDA approved NDA 205677 in October 2013 for treatment of mild-to-moderate acute pain in adults and osteoarthritis pain in adults. The product uses diclofenac acid in a submicron particle formulation. [1]

The Orange Book analysis is product-specific. A patent is not automatically an Orange Book-listed patent merely because its claims cover the same formulation. The relevant questions are:

1. Whether the patent was submitted by the NDA holder.
2. Whether FDA accepted the patent for listing.
3. Whether the listed patent claims the drug substance, drug product or approved method of use.
4. Whether a pending ANDA applicant must make a Paragraph IV certification.
5. Whether the listing remains active on the relevant Orange Book date.

The Orange Book must be checked by NDA number and product presentation. Patent listings can differ by strength, dosage form and approved use. A patent that is technically relevant but not listed may still support a conventional infringement action, but it may not generate the same ANDA notice and 30-month-stay consequences as a listed patent.

Which companies are challenging the diclofenac formulation estate?

The relevant competitive field includes generic manufacturers of diclofenac capsules and companies selling alternative diclofenac dosage forms. Potential challengers include manufacturers pursuing:

• ANDA approval for 18 mg or 35 mg diclofenac capsules.
• Diclofenac potassium immediate-release tablets.
• Diclofenac sodium delayed-release tablets.
• Liquid-filled diclofenac capsules.
• Topical diclofenac products.
• Injectable diclofenac products.
• Non-oral diclofenac formulations.

A company challenging a listed patent through Paragraph IV would need to address both patent validity and noninfringement. Typical grounds include:

• Anticipation by earlier nanoparticulate diclofenac disclosures.
• Obviousness based on known particle-size reduction and conventional capsule excipients.
• Lack of written description for the full particle-size and dissolution combinations.
• Lack of enablement across the full 18 mg and 35 mg claim scope.
• Indefiniteness involving “volume average,” “median particle size,” “D(90)” or clinical timing terms.
• Failure to meet the statutory requirements for an Orange Book-listed method-of-use claim.

No Paragraph IV challenge or settlement can be inferred from the claims alone. The existence, timing and terms of any challenge must be confirmed through FDA ANDA records, district court dockets and settlement filings.

How strong is the patent estate for Zorvolex and similar products?

US 8,679,544 is strongest against a product that reproduces the commercial architecture:

• 18 mg or 35 mg diclofenac acid;
• Submicron diclofenac particles;
• Lactose monohydrate;
• Sodium lauryl sulfate;
• Rapid dissolution;
• Hard gelatin capsule;
• The specified secondary excipients.

Its protection is weaker against alternative dosage forms and active-ingredient forms. The main design-around paths are:

Design-around	Likely effect under US 8,679,544
Use diclofenac potassium or sodium	May avoid the diclofenac-acid limitation
Use a dose other than 18 mg or 35 mg	Avoids the two independent claims
Replace lactose monohydrate	May avoid the required excipient combination
Remove or replace sodium lauryl sulfate	May avoid the independent claims
Use particles outside the 25-500 nm median range	May avoid literal particle-size infringement
Use slower dissolution	May avoid the performance limitation
Use tablet, liquid or injectable dosage form	May avoid capsule-dependent claims, but not independent claims if all other limitations are present
Retain the formula but use a different manufacturing process	Does not avoid composition claims if the final product has the claimed properties

The patent’s main weakness is its dependence on measurable product attributes. Particle size and dissolution can be tested directly, which supports infringement analysis, but the same limitations create potential invalidity and reproducibility challenges.

What manufacturing and intellectual-property barriers exist?

The formulation appears to rely on particle-size reduction sufficient to produce a submicron diclofenac acid distribution while maintaining capsule manufacturability and rapid release. Relevant manufacturing barriers include:

• Controlling agglomeration during milling or nanoparticle production.
• Maintaining the 25-500 nm median range at commercial scale.
• Limiting the D(90) coarse-particle fraction.
• Achieving consistent blend uniformity at low drug loading.
• Preserving dissolution performance after encapsulation and storage.
• Demonstrating batch-to-batch comparability under the specified USP method.

A process patent may create risk even when a finished product avoids US 8,679,544. Conversely, a process change may not avoid this patent because the claims are directed primarily to the finished unit dose and its measurable characteristics.

How does this patent compare with competing diclofenac products?

Product category	Typical active form	Typical release profile	Relationship to US 8,679,544
Zorvolex capsules	Diclofenac acid	Immediate release	Closest commercial target
Cataflam tablets	Diclofenac potassium	Immediate release	Different salt and dosage form
Voltaren and generic delayed-release tablets	Diclofenac sodium	Delayed or enteric release	Different salt and release system
Zipsor liquid-filled capsules	Diclofenac potassium	Immediate release	Different salt and formulation
Dyloject injection	Diclofenac sodium	Parenteral	Different route and dosage form
Topical diclofenac gels and solutions	Diclofenac sodium or other form	Topical delivery	Outside the oral unit-dose architecture

The patent is therefore a targeted barrier to a particular oral nanoparticulate diclofenac platform, not a field-wide barrier to generic diclofenac competition.

Key Takeaways

• US 8,679,544 has two independent composition claims covering 18 mg and 35 mg diclofenac acid unit doses.
• Both claims require lactose monohydrate, sodium lauryl sulfate, diclofenac particles with a median volume-average size above 25 nm and below 500 nm, and specified dissolution performance.
• Claims 11-18 add capsule, excipient and D(90) limitations.
• Claims 19-24 add Tmax and human pain-relief comparisons but are more difficult to prove in litigation.
• The patent is most relevant to Zorvolex-type diclofenac acid capsules.
• Diclofenac salts, different strengths, alternative excipients, different particle-size distributions and different dissolution profiles provide potential design-around routes.
• FDA approval of Zorvolex does not by itself establish that US 8,679,544 is currently listed in the Orange Book.
• A precise expiration date requires review of the patent family’s priority chain, patent-term adjustment, terminal disclaimers, maintenance fees and any patent-term extension.
• Generic risk cannot be assessed from this patent alone. Related formulation, method-of-use, process and Orange Book-listed patents may materially extend the commercial barrier.

FAQs About US Patent 8,679,544

Does US 8,679,544 cover generic diclofenac tablets?

No. The claims are directed to particular diclofenac acid unit doses with submicron particles, specified excipients and dissolution performance. Conventional diclofenac sodium or diclofenac potassium tablets generally have a different claim profile.

Can a generic manufacturer avoid the patent by using diclofenac potassium?

Potentially. Diclofenac potassium may avoid the literal “diclofenac acid” limitation, but the manufacturer must review separate patents covering diclofenac potassium formulations, dosage forms, methods of use and manufacturing.

Is a 35 mg product automatically infringing?

No. The product must also contain the required diclofenac acid particle-size distribution, lactose monohydrate, sodium lauryl sulfate and dissolution profile. A 35 mg strength alone is insufficient.

Are nanoparticle claims vulnerable to particle-size testing disputes?

Yes. Measurement conditions, agglomeration, dispersion and instrument methodology can materially affect median size and D(90). The patent’s specified measurement basis is therefore important in both infringement and validity disputes.

Does FDA approval prove that the patent is valid?

No. FDA approval addresses safety, efficacy, quality and regulatory requirements. Patent validity and infringement are determined under US patent law, generally by the courts or the Patent Trial and Appeal Board.

References

1. U.S. Food and Drug Administration. (2013). Zorvolex (diclofenac) capsules: Prescribing information and approval information. https://www.accessdata.fda.gov
2. U.S. Patent and Trademark Office. (2014). US Patent No. 8,679,544, pharmaceutical composition claims for diclofenac acid unit doses. https://patents.google.com/patent/US8679544
3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
4. United States Code. (2024). 35 U.S.C. §§ 154, 156 and 271. https://uscode.house.gov
5. United States Pharmacopeia. (2024). General chapter <711>: Dissolution. https://www.usp.org/compounding/general-chapter-711-dissolution

Drugs Protected by US Patent 8,679,544

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Zyla	ZORVOLEX	diclofenac	CAPSULE;ORAL	204592-001	Oct 18, 2013		DISCN	Yes	No	8,679,544		Y
Zyla	ZORVOLEX	diclofenac	CAPSULE;ORAL	204592-002	Oct 18, 2013		DISCN	Yes	No	8,679,544		Y

Foreign Priority and PCT Information for Patent: 8,679,544

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Australia	2009901748	Apr 24, 2009

International Family Members for US Patent 8,679,544

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
African Regional IP Organization (ARIPO)	3774
Australia	2010239080
Australia	2014208310
Brazil	PI1014272
Canada	2759123
China	102438610