US Patent 8,623,920: Scope, Claims, Expiration, and Diclofenac Patent Landscape

US Patent No. 8,623,920 protects a narrow clinical-use regimen for diclofenac potassium in a dispersible liquid formulation. The core claim requires treatment of acute moderately severe to severe post-surgical pain after internal fixation of a bone deformity, using 20 to 30 mg every four to eight hours, with a maximum daily dose of 100 mg and an average 48-hour pain-intensity difference above two NPRS units.[1]

The patent does not broadly cover diclofenac, diclofenac potassium, all oral liquid formulations, or all post-operative pain treatment. Its commercial relevance depends on whether a product, label, prescribing practice, or clinical protocol satisfies every limitation of claim 1.

What does US Patent 8,623,920 protect?

US 8,623,920 is a method-of-treatment patent. Its claims combine:

A defined patient condition: acute moderately severe to severe post-surgical pain.
A defined surgical setting: correction of a bone deformity involving internal fixation.
A defined drug: diclofenac potassium.
A defined formulation: a dispersible liquid formulation.
A defined dose: about 20 to 30 mg.
A defined dosing interval: about every four to eight hours.
A defined exposure limit: no more than about 100 mg in 24 hours.
A defined clinical result: average 48-hour PID greater than two NPRS units.

The claim is cumulative. A competing product or use must meet all required elements to fall within claim 1.

Core claim chart

Claim element	Requirement in claim 1	Scope implication
Disease or condition	Acute moderately severe to severe post-surgical pain	Excludes ordinary chronic pain and routine mild pain
Pain measurement	NPRS scale of 0 to 10	Adds a clinical-severity limitation
Surgery	Correction of a bone deformity	Narrows the use beyond general surgery
Surgical technique	Internal fixation	Relevant to orthopedic procedures using implanted fixation hardware
Active ingredient	Diclofenac potassium	Does not expressly cover diclofenac sodium or another salt
Formulation	Dispersible liquid formulation	Central formulation limitation
Dose	About 20 to 30 mg	Includes the expressly claimed 20, 22.5, 25, 27.5, 28, and 30 mg embodiments
Interval	About every 4 to 8 hours	Claims 2 and 3 narrow the interval to five to eight hours and about six hours
Treatment duration	At least 48 hours	Dependent claims extend the stated periods through seven days
Daily maximum	Less than or equal to about 100 mg	Excludes regimens exceeding the claimed daily ceiling
Clinical outcome	Average PID over 48 hours greater than two units	Creates a performance-based limitation

The practical center of gravity is a 25 mg oral diclofenac potassium liquid formulation administered four times daily for acute orthopedic pain, with a total daily dose of 100 mg.

How broad is claim 1 of US 8,623,920?

Claim 1 is narrow in patient population and clinical context but potentially meaningful against a labeled product used in orthopedic post-operative care.

The claim requires internal fixation following correction of a bone deformity. Examples could include osteotomy or corrective orthopedic surgery involving plates, screws, rods, or other fixation devices. The claim does not expressly cover every operation involving internal fixation. The procedure must be characterized as surgical correction of a bone deformity, and the treated pain must be acute, post-surgical, and moderately severe to severe.

The claim also requires a dispersible liquid formulation. That phrase creates a formulation-specific limitation. A conventional immediate-release tablet, standard capsule, injectable solution, or topical formulation would not literally satisfy this element unless the product is properly characterized as a dispersible liquid formulation.

The use of "about" broadens the numerical ranges, but it does not eliminate the need to prove that the accused regimen falls reasonably close to the stated values. The boundaries of "about 20 to 30 mg," "about every 4 to 8 hours," and "about 100 mg" would depend on intrinsic evidence, prosecution history, technical evidence, and the facts of the accused use.

What do claims 2 through 20 add?

Claims 2 through 20 are dependent claims. They do not expand claim 1. Each incorporates all limitations of claim 1 and adds a narrower requirement.

Dosing and duration claims

Claims 2 and 3 narrow the dosing interval:

Claim 2: approximately every five to eight hours.
Claim 3: approximately every six hours.

Claim 4 specifies treatment for approximately 72 hours. Claim 5 lists treatment periods of at least 48, 72, 96, 120, 144, or 168 hours, including seven days.

These claims may be useful where a label or clinical protocol specifies a six-hour regimen or a multi-day course. They are less useful against a product used only once or for less than 48 hours.

Dose-specific claims

Claim 6 identifies doses of approximately:

20 mg
22.5 mg
25 mg
27.5 mg
28 mg
30 mg

Claim 11 separately focuses on approximately 25 mg. Claim 16 specifies 25 mg four times over approximately 24 hours, which corresponds to a 100 mg daily total.

A 25 mg dose administered four times daily is the most commercially important claimed embodiment because it aligns with a conventional 100 mg maximum daily regimen.

Pharmacokinetic and pharmacodynamic claims

Claims 7 through 10 add pharmacokinetic or duration-of-effect limitations:

Relief lasting approximately six to eight hours.
Plasma diclofenac concentrations of approximately 670 to 1,500 ng/mL in less than 30 minutes.
A Tmax of approximately 0.47 hours.
Substantial elimination from plasma within the first two hours.

These limitations may be difficult to establish in ordinary infringement litigation because they require patient-level pharmacokinetic or clinical evidence. A product may have the same dose and formulation but fail to meet a specific concentration or Tmax limitation.

Claim 10 is particularly unusual. A short plasma persistence requirement may distinguish the claimed formulation from a sustained-release or extended-release formulation, but it also creates a factual proof issue concerning the meaning of "substantially eliminated."

Clinical-outcome claims

Claims 12 through 15 add specific clinical outcomes for the 25 mg regimen:

An average 48-hour NPRS-related score of approximately 249.
Median time to at least 30% pain reduction of approximately 60 minutes.
Median time to meaningful pain relief of approximately 70 minutes.
Clinically significant analgesic efficacy for approximately six hours.

The wording of claim 12 appears internally unusual because an NPRS ordinarily ranges from 0 to 10, while "about 249" is more consistent with a summed pain-intensity-difference or SPID-type endpoint. The issued claim controls unless corrected or construed in light of the specification and prosecution history. The discrepancy could create an indefiniteness, written-description, or claim-construction issue, depending on the intrinsic record.[1]

Product and co-medication claims

Claim 17 requires the diclofenac potassium formulation to be contained in a capsule. Claim 18 requires that no opioid be co-administered.

Claim 18 is a negative limitation. Infringement would require evidence that the claimed diclofenac regimen is used without opioid co-administration. A label authorizing opioid rescue medication may not alone establish infringement of a no-opioid limitation, but actual prescribing instructions and promotional activity could become relevant to inducement.

Claims 19 and 20 narrow the pain condition to severe pain and approximately NPRS 7, respectively.

What is the likely protected commercial product?

The claims are directed toward a rapid-onset oral diclofenac potassium liquid product, particularly a 25 mg capsule or similar dispersible liquid formulation. The claim architecture is consistent with a product positioned for acute pain where rapid absorption, early analgesia, and a maximum 100 mg daily dose are important.

A product may be technically similar to the claimed formulation but outside the method claims if it is:

Used for dental, menstrual, musculoskeletal, or general acute pain rather than post-surgical pain.
Used after a surgery unrelated to correction of a bone deformity.
Used without internal fixation.
Administered at a dose below 20 mg or above 30 mg.
Administered outside the claimed interval.
Administered for less than 48 hours.
Formulated as a non-dispersible tablet or a different dosage form.
Used with a daily dose above 100 mg.
Used with opioid co-administration where claim 18 is at issue.

The patent therefore has stronger protection against a matching labeled indication and regimen than against broad substitution by another diclofenac product.

When does US Patent 8,623,920 expire?

The patent’s ordinary term is generally calculated from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and any applicable correction. The number alone does not establish the precise expiration date.

The relevant legal framework is 35 U.S.C. §154, which generally provides a term ending 20 years from the earliest effective US nonprovisional filing date, subject to statutory adjustments.[2] The authoritative expiration date should be taken from the USPTO patent record and any applicable Orange Book listing rather than inferred from the issue date.

Patent-term considerations

Issue	Relevance
Earliest effective filing date	Controls the base 20-year term
Patent-term adjustment	Can extend the term for USPTO prosecution delays
Patent-term extension	May apply only if statutory regulatory requirements are met
Terminal disclaimer	Could limit the term to another patent’s expiration
Continuation status	May result in a later-issued patent with an earlier effective filing date
Orange Book listing	Can identify listed patents and use-code information, but does not independently determine validity

A definitive freedom-to-operate date requires review of the USPTO continuity data, patent-term calculation, terminal-disclaimer records, and any FDA patent listing associated with the relevant product.

What is the Orange Book status of the patent?

The FDA Orange Book identifies patents submitted by NDA sponsors for approved drug products and, where applicable, associates them with method-of-use codes.[3] A patent’s presence or absence in the Orange Book is commercially important but does not determine validity or infringement.

For a method patent such as US 8,623,920, the relevant questions are:

Whether it is listed against an approved diclofenac potassium product.
Whether the listing has a corresponding use code.
Whether the use code covers orthopedic post-surgical pain or a broader indication.
Whether the listing remains active.
Whether the approved labeling contains the claimed regimen and patient population.

If the patent is listed for a drug product, an ANDA applicant seeking approval for a use covered by that listing may need to submit a Paragraph IV certification. If the applicant omits the patented use through a section viii statement, the outcome depends on whether the remaining proposed label still induces use within the patent’s scope.[4]

How would a generic applicant challenge US 8,623,920?

A generic applicant could pursue several routes.

Paragraph IV invalidity challenge

A Paragraph IV certification could assert that the patent is invalid, unenforceable, or not infringed. The principal attack points would likely include:

Obviousness of using a known diclofenac potassium formulation for post-operative pain.
Obviousness of the 20 to 30 mg dose and 100 mg daily maximum.
Obviousness of dosing every six hours.
Lack of written description for the combined orthopedic surgery, internal fixation, pain severity, formulation, and clinical-outcome limitations.
Indefiniteness of terms such as "dispersible liquid formulation," "about," "substantially eliminated," and the "about 249" NPRS limitation.
Enablement of the full claimed range of patients, surgeries, doses, intervals, and clinical outcomes.
Failure to demonstrate that the claimed clinical result is a reliable limitation across the full scope.

The strongest invalidity theory would likely depend on prior-art combinations showing: an oral diclofenac potassium liquid formulation, acute post-operative analgesia, orthopedic internal fixation, a 25 mg dose, and a four-times-daily regimen.

Section viii carve-out

A generic applicant may attempt to omit the patented method from its label while retaining approval for non-infringing uses. That strategy is more feasible if the patent’s use code is narrow and the product has commercially meaningful indications outside orthopedic post-surgical pain.

A carve-out is less effective if the generic label, dosing instructions, promotional materials, or ordinary clinical use would still direct physicians toward the patented method. Courts assess the totality of inducement evidence, not only the presence of an express indication.

What patent litigation affects this patent?

The claim set creates litigation exposure at both the product and use levels.

Likely infringement theories

A patent holder could assert:

Direct infringement against a physician or healthcare provider using the regimen.
Induced infringement against a manufacturer whose label or promotional materials encourage the claimed use.
Contributory infringement if the product is especially adapted for the patented method and has limited substantial non-infringing uses.

For an ANDA product, the central dispute would likely concern the proposed label and whether the generic’s instructions encourage treatment after bone-deformity correction with internal fixation.

Likely defenses

A defendant could argue:

The formulation is not a dispersible liquid formulation.
The product contains diclofenac sodium rather than diclofenac potassium.
The use is not correction of a bone deformity.
The surgery does not include internal fixation.
The dose or interval falls outside the claim.
Treatment lasts less than 48 hours.
The label does not require or encourage the claimed clinical outcome.
Opioids are co-administered, defeating claim 18.
The asserted claims are invalid for obviousness or indefiniteness.

The performance limitations in claims 8 through 15 could reduce the patent holder’s ability to prove infringement through label evidence alone. Those claims may require clinical studies, pharmacokinetic testing, or expert statistical analysis.

How strong is the patent estate for this diclofenac formulation?

US 8,623,920 appears strongest as a narrow use patent and weaker as a platform patent.

Protection category	Relative strength	Reason
Diclofenac active ingredient	Low	Diclofenac and its salts are longstanding compounds
General acute-pain use	Low to moderate	Broad use claims would face substantial prior art
Specific liquid formulation	Moderate	Depends on formulation definition and competing dosage forms
25 mg dosing regimen	Moderate	Commercially clear but potentially vulnerable to obviousness
Orthopedic internal-fixation use	Moderate to strong	Narrow patient and surgical context
Six-hour dosing	Moderate	Specific but clinically conventional
Pharmacokinetic profile	Variable	Potentially distinctive, but difficult to prove
No-opioid use	Narrow	Can create proof and inducement issues
Seven-day duration	Narrow	Adds duration but may not materially increase commercial coverage

The patent’s value depends more on label control and product differentiation than on broad exclusion of all generic diclofenac products.

What other patents may cover diclofenac potassium products?

A complete patent landscape should separate five categories:

Active ingredient and salt patents

Older patents may cover diclofenac, diclofenac potassium, or pharmaceutical salts. These patents are generally less important for current US entry because diclofenac has been marketed for decades and early compound claims have typically expired.

Formulation patents

Formulation patents may cover:

Liquid-filled capsules.
Dispersible or rapidly dispersing dosage forms.
Particle-size control.
Solubilization systems.
Enteric protection.
Taste masking.
Immediate-release delivery.
Modified-release delivery.
Stabilizers and excipients.

These patents can create more meaningful barriers than an expired compound patent, particularly where the product’s performance depends on rapid dissolution or absorption.

Method-of-use patents

Method patents may cover:

Acute post-operative pain.
Dental pain.
Musculoskeletal pain.
Migraine or episodic pain.
Opioid-sparing treatment.
Specific doses or dosing intervals.
Treatment of patients with defined pain scores.
Use after orthopedic procedures.

US 8,623,920 belongs principally in this category, although its claims also depend on a formulation limitation.

Manufacturing patents

Manufacturing claims may cover:

Preparation of diclofenac potassium.
Filling of liquid capsules.
Control of particle size or polymorphic form.
Manufacturing of dispersible suspensions.
Encapsulation and sealing processes.
Stability control and packaging.

Manufacturing patents may affect supply even when a generic avoids the method-of-use claims through a label carve-out.

Regulatory exclusivity

FDA regulatory exclusivity is separate from patent protection. For an ordinary small-molecule NDA, five-year new chemical entity exclusivity, three-year clinical-investigation exclusivity, pediatric exclusivity, and orphan-drug exclusivity may be relevant depending on the product and approval history.[4] These periods do not extend the patent term, although pediatric exclusivity can add six months to certain listed protections.

Which companies could challenge or compete with the protected product?

Competition is likely to arise from several product categories:

Competitor type	Product or approach	Patent risk
Generic diclofenac potassium tablets	Conventional immediate-release tablets	May avoid the dispersible-liquid limitation
Generic diclofenac sodium products	Different active salt	May avoid literal diclofenac potassium claims
Diclofenac potassium oral solution	Same active salt and liquid concept	Higher formulation and method risk
Liquid-filled capsule products	Similar dosage form	Higher risk if formulation and labeling align
Diclofenac injection	Parenteral product	Outside the oral-administration limitation
Opioid combinations	Multimodal analgesia	May conflict with the no-opioid dependent claim
Other NSAIDs	Ibuprofen, ketorolac, naproxen, celecoxib	Avoid diclofenac-specific claims
Local anesthetic products	Regional or local post-operative analgesia	Compete therapeutically without practicing the claims

The most direct challenger would be a generic or reformulated oral diclofenac potassium liquid product seeking an orthopedic post-surgical indication. A conventional diclofenac tablet generic has a lower literal infringement risk but may still compete commercially.

What generic launch scenarios exist?

Scenario 1: Paragraph IV litigation

A generic seeks approval for labeling that includes the patented orthopedic use and challenges the patent. Litigation could trigger the 30-month stay under the Hatch-Waxman framework if statutory requirements are met.[4] Launch timing would depend on litigation outcome, settlement terms, patent-term calculations, and any exclusivity held by a first Paragraph IV filer.

Scenario 2: Section viii carve-out

The generic removes the patented orthopedic use from its label. This may permit earlier approval if the remaining label does not encourage the patented method. The commercial value of the carve-out depends on the size of the non-patented acute-pain market.

Scenario 3: Design-around formulation

A competitor uses:

Diclofenac sodium rather than potassium.
A non-liquid tablet.
A non-dispersible formulation.
A dose outside the claimed range.
A dosing interval outside four to eight hours.
A different delivery route.

This strategy may avoid literal infringement but could introduce separate formulation, bioequivalence, or clinical-development requirements.

Scenario 4: Post-expiration launch

A generic waits until the patent and any applicable regulatory exclusivity expire. This avoids litigation risk but sacrifices first-mover timing and may permit competing products to establish prescriber share.

What is the geographic coverage of US 8,623,920?

US 8,623,920 provides rights only in the United States. It does not automatically cover Canada, Europe, Japan, China, or other jurisdictions.

International protection would require corresponding national or regional patents, commonly originating from the same priority family. Each jurisdiction may differ in:

Claim scope.
Patent expiration.
Patent-term adjustment or supplementary protection.
Permitted medical-use claim formats.
Patent-linkage procedures.
Generic or biosimilar challenge mechanisms.
Enforcement standards.

The patent does not create biosimilar risk because diclofenac potassium is a conventional small-molecule drug, not a biologic. The relevant competitive pathway is an ANDA or other small-molecule approval route, not a biosimilar application under the Public Health Service Act.

What revenue exposure does this patent create?

Revenue exposure is concentrated in products that combine:

Diclofenac potassium.
A dispersible liquid oral formulation.
A 20 to 30 mg dose, especially 25 mg.
Use for acute post-surgical orthopedic pain.
Four-times-daily or approximately six-hour administration.
A 100 mg daily maximum.

The patent is less capable of blocking revenue from the broader diclofenac market because most competing products can differ in salt, formulation, indication, route, or label.

A commercial assessment should therefore distinguish between:

Revenue tied to the protected product label.
Revenue from unprotected indications.
Revenue from formulations outside the claim.
Revenue exposed only if physicians use the product after internal-fixation surgery.
Revenue protected by other formulation or manufacturing patents.

Key Takeaways

US 8,623,920 is a narrow method-of-treatment patent, not a broad diclofenac composition patent.
Claim 1 requires a specific orthopedic surgery, internal fixation, acute pain severity, oral diclofenac potassium liquid formulation, 20 to 30 mg dosing, four- to eight-hour intervals, a 100 mg daily ceiling, and a specified 48-hour analgesic result.
The commercially important embodiment is 25 mg administered four times daily for approximately 48 to 72 hours.
Claims 8 through 15 add pharmacokinetic and clinical-performance limitations that may be difficult to prove in litigation.
A conventional diclofenac tablet, diclofenac sodium product, injectable product, or non-orthopedic use may avoid literal infringement.
A generic applicant could use Paragraph IV, a section viii carve-out, or a formulation design-around.
The patent has no biosimilar relevance because diclofenac potassium is a small-molecule drug.
Exact expiration and current Orange Book status must be determined from the USPTO continuity and patent-term records and the FDA’s current Orange Book listing.
Patent value is concentrated in label protection and product-specific differentiation rather than broad exclusion of diclofenac competitors.

Frequently Asked Questions

Does US 8,623,920 cover all 25 mg diclofenac products?

No. It covers a specific 25 mg diclofenac potassium dispersible liquid regimen used for the claimed orthopedic post-surgical pain indication and satisfying the remaining limitations of claim 1.

Does a diclofenac sodium generic infringe this patent?

Not literally under the active-ingredient limitation, because the claims specify diclofenac potassium. Literal infringement would require a product containing the claimed potassium salt, although other patent or inducement theories could present separate issues.

Can a generic sell diclofenac potassium for dental pain?

Potentially. Dental pain may fall outside claim 1 because the claim requires pain resulting from surgical correction of a bone deformity involving internal fixation. The generic’s label and actual use would control the infringement analysis.

Is claim 18 a broad opioid-sparing claim?

No. Claim 18 is narrower. It requires that no opioid be co-administered with the diclofenac potassium formulation. It does not broadly cover every opioid-sparing treatment strategy.

Are the pharmacokinetic limitations automatically satisfied by a 25 mg dose?

No. A 25 mg dose alone does not establish a plasma concentration range, a 0.47-hour Tmax, or substantial plasma elimination within two hours. Those limitations require separate technical proof.

References

United States Patent No. 8,623,920, claims 1-20. U.S. Patent and Trademark Office.
35 U.S.C. § 154. Patent term.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application submissions and patent certifications. 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
Cosette	ZIPSOR	diclofenac potassium	CAPSULE;ORAL	022202-001	Jun 16, 2009	AB	RX	Yes	Yes	8,623,920	⤷ Start Trial				DICLOFENAC POTASSIUM FOR RELIEF OF MILD TO MODERATE ACUTE 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

Summary for Patent: 8,623,920