Details for Patent: 9,119,791

Which drugs does patent 9,119,791 protect, and when does it expire?

Patent 9,119,791 protects OXTELLAR XR and is included in one NDA.

This patent has fourteen patent family members in ten countries.

Summary for Patent: 9,119,791

Title:	Modified release preparations containing oxcarbazepine and derivatives thereof
Abstract:	Controlled-release preparations of oxcarbazepine and derivatives thereof for once-a-day administration are disclosed. The inventive compositions comprise solubility- and/or release enhancing agents to provide tailored drug release profiles, preferably sigmoidal release profiles. Methods of treatment comprising the inventive compositions are also disclosed.
Inventor(s):	Padmanabh P. Bhatt, Argaw Kidane, Kevin Edwards
Assignee:	Supernus Pharmaceuticals Inc
Application Number:	US14/445,233
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 9,119,791
Patent Claim Types: see list of patent claims	Use; Composition; Formulation; Dosage form;

US Patent 9,119,791: Oxcarbazepine Extended-Release Formulation Scope, Claims, and Patent Landscape

US Patent 9,119,791 covers a once-daily oxcarbazepine formulation designed to produce controlled, sigmoidal release and reduce fluctuations in the active metabolite, 10-monohydroxy derivative of oxcarbazepine, commonly called MHD. The patent is directed primarily to the formulation architecture and its use in seizure treatment, rather than to oxcarbazepine as an active pharmaceutical ingredient.

The claim set is commercially relevant to extended-release oxcarbazepine products such as Oxtellar XR. The principal infringement risk is concentrated in claim 1, which requires a specific combination of a homogeneous matrix, a solubility-enhancing agent, and a pH-dependent release-promoting polymer.

What does US Patent 9,119,791 cover?

The patent covers a method of treating seizures by administering oxcarbazepine once daily in a formulation containing four required components:

Required element	Claim 1 requirement
Active ingredient	Oxcarbazepine
Dosage frequency	Once daily
Physical structure	Homogeneous matrix
Matrix-forming polymer	1% to 50% by formulation weight
Solubility-enhancing agent	1% to 80% by formulation weight
Release-promoting agent	10% to 90% by formulation weight
Release-promoting polymer	pH-dependent polymer from a defined list

The release-promoting polymer must remain intact in acidic conditions below pH 4 and dissolve at higher pH levels. Dependent claims progressively narrow the pH dissolution threshold to above pH 5 and above pH 6.

The claim is therefore not satisfied by every extended-release oxcarbazepine tablet. A competing product must generally practice the claimed matrix and polymer combination, meet the quantitative ranges, and be administered once daily for seizure treatment.

How broad is independent claim 1?

Claim 1 is technically broad in its selection of excipients but narrow in its required combination.

Required formulation architecture

The claim requires a "homogeneous matrix." This language is potentially significant. A homogeneous matrix generally implies that oxcarbazepine and the functional excipients are distributed throughout a unified matrix rather than separated into discrete coating layers, beads, pellets, or independently coated particles.

A product using a multiparticulate system could face a claim-construction dispute if the commercial dosage form is ultimately compressed into a tablet but the active-containing pellets are not homogeneous at the particle level. The infringement analysis would depend on how "formulation" and "homogeneous matrix" are construed and whether the relevant matrix is the final dosage form or an internal subunit.

Quantitative limitations

Claim 1 requires the following weight ranges:

• Matrix-forming polymer: 1% to 50%.
• Solubility-enhancing agent: 1% to 80%.
• pH-dependent release-promoting agent: 10% to 90%.

These ranges overlap substantially. A formulation containing 20% HPMC, 10% sodium lauryl sulfate, and 40% Eudragit L100-55 would fall within the stated numerical ranges, assuming the other limitations were met.

The percentages are limitations, not merely preferred embodiments. A formulation outside any required range could avoid literal infringement, although doctrine-of-equivalents issues could remain depending on the product and jurisdiction.

Closed polymer selection

The pH-dependent release-promoting polymer is selected from a defined list:

• Cellulose acetate phthalate.
• Cellulose acetate succinate.
• Methylcellulose phthalate.
• Ethylhydroxycellulose phthalate.
• Polyvinyl acetate phthalate.
• Polyvinylbutyrate acetate.
• Vinyl acetate-maleic anhydride copolymer.
• Styrene-maleic mono-ester copolymer.
• Eudragit L100-55.
• Methyl acrylate-methacrylic acid copolymers.

The "selected from the group consisting of" language ordinarily creates a closed Markush group. A product using a different enteric or pH-sensitive polymer may have a noninfringement position under the literal claim, subject to equivalence analysis.

What do dependent claims add?

The dependent claims create several commercially meaningful fallback positions.

Claims	Subject matter
2-3	Matrix-forming polymers, including HPMC, HPC, HEC, MC, cellulose derivatives, alginates, gums, polyethylene oxides, and polyvinyl alcohol
4-5	Solubility enhancers, including surfactants, complexing agents, cyclodextrins, pH modifiers, hydration promoters, sodium docusate, sodium lauryl sulfate, and poloxamer-type materials
6-8	pH-dependent polymer remains intact below pH 4 and dissolves above pH 4, 5, or 6
9	Sigmoidal in-vitro oxcarbazepine release
10	Repeats the quantitative polymer and solubility-enhancer ranges
11-13	Lubricants and waxes, generally at 0.1% to 20%
14-16	MHD steady-state and fluctuation limitations
17, 20	600 mg oxcarbazepine dosage strength
18-19	Pellets, tablets, granules, or capsules, with tablets specifically claimed
21-24	Epileptic, partial, generalized tonic-clonic seizures, and adult or pediatric subjects

Claims 17 and 20 are particularly relevant to a 600 mg once-daily tablet. Claim 20 is drafted as "the formulation of claim 19," although claim 19 is written as a method claim. That mixed claim-category dependency creates a potential issue in claim interpretation and prosecution-history review. It does not automatically invalidate the claim, but it could complicate enforcement.

Which formulations are most exposed to US 9,119,791?

The highest-risk product profile is a once-daily 600 mg oxcarbazepine tablet containing:

1. Oxcarbazepine dispersed in a homogeneous hydrophilic matrix.
2. HPMC or another listed matrix polymer.
3. Sodium lauryl sulfate, sodium docusate, a cyclodextrin, or another listed solubility enhancer.
4. Eudragit L100-55 or another listed pH-dependent polymer.
5. Release characteristics that are sigmoidal in vitro.
6. Use for epilepsy or seizure treatment.

A product that uses Eudragit L100-55 in a coating rather than in a matrix could dispute whether it contains the claimed "release-promoting agent" within the claimed homogeneous matrix. A product using a nonlisted pH-sensitive polymer could avoid the closed polymer limitation. A twice-daily product would not satisfy the once-daily limitation, although the marketed product label and actual prescribing instructions would be relevant to method-of-use analysis.

Formulation risk matrix

Competing formulation characteristic	Exposure level
Once-daily oxcarbazepine tablet	High
600 mg once-daily tablet	High
HPMC matrix plus Eudragit L100-55	Very high
Listed surfactant or cyclodextrin	Increases risk
Multiparticulate pellet product	Moderate, construction-dependent
Nonlisted pH-dependent polymer	Lower literal risk
Immediate-release oxcarbazepine	Low
Twice-daily extended-release product	Lower, based on frequency limitation
Oxcarbazepine prodrug or different active ingredient	Low

What is the relationship to Oxtellar XR?

Oxtellar XR is a once-daily extended-release oxcarbazepine product marketed by Supernus Pharmaceuticals. FDA approved Oxtellar XR in 2012 for adjunctive therapy in adults and children with partial seizures. The product uses an extended-release technology intended to control oxcarbazepine exposure and MHD concentration over the dosing interval. [1]

US Patent 9,119,791 is associated with the controlled-release oxcarbazepine formulation patent estate supporting this product. The patent claims are consistent with a formulation strategy that combines a matrix system, solubility enhancement, and pH-dependent release control.

Trileptal, the older immediate-release oxcarbazepine product, is commercially distinct. Its active ingredient is not itself protected by this patent. Generic immediate-release oxcarbazepine products therefore do not inherently practice the once-daily controlled-release formulation claimed in US 9,119,791.

When does US Patent 9,119,791 lose exclusivity?

US 9,119,791 was granted on August 25, 2015. Its statutory expiration is determined by the earliest effective nonprovisional priority date, subject to patent-term adjustment and any applicable patent-term extension. A grant date alone does not establish the expiration date.

For a pharmaceutical patent filed after June 8, 1995, the ordinary term is 20 years from the earliest effective US nonprovisional filing date, not 20 years from issuance. Patent-term adjustment shown on the USPTO patent face and any terminal disclaimer can materially change the end date. [2]

The patent's enforceable life must therefore be determined from:

• The earliest effective priority and nonprovisional filing dates.
• Any terminal disclaimer.
• Patent-term adjustment.
• Patent-term extension, if granted.
• Post-grant corrections or disclaimers.
• The current Orange Book listing and delisting record.

The patent number and grant date alone do not establish a reliable commercial launch date for an ANDA applicant.

What is the Orange Book status of US 9,119,791?

The Orange Book determines whether a patent is listed against an approved drug product and whether the listing concerns the active ingredient, formulation, or method of use. FDA's Orange Book distinguishes patent categories through product-specific listing information and use-code descriptions. [3]

For Oxtellar XR, the relevant analytical questions are:

• Whether US 9,119,791 remains listed against the NDA.
• Whether it is listed as a formulation patent or method-of-use patent.
• Whether the listed use code covers seizure treatment or a narrower indication.
• Whether the patent has been delisted, corrected, or replaced.
• Whether a later-issued continuation or divisional patent provides overlapping protection.

The supplied claim text does not establish the current Orange Book listing status. Orange Book status is separate from claim scope and must be assessed from the FDA's current patent listing record.

What Paragraph IV risks exist for generic oxcarbazepine?

A generic applicant seeking approval of a once-daily extended-release oxcarbazepine product may need to address listed patents through an ANDA certification under the Hatch-Waxman Act. The relevant options include:

• Paragraph III certification, accepting approval after patent expiration.
• Paragraph IV certification, asserting that the patent is invalid, unenforceable, or not infringed.
• A section viii statement, where the relevant patent claims a method of use that can be carved out of the proposed label.
• A certification based on patent delisting or lack of applicability.

A Paragraph IV notice concerning US 9,119,791 could focus on several theories:

Noninfringement theories

• The formulation lacks a homogeneous matrix.
• The pH-dependent polymer is not one of the listed polymers.
• The polymer is not present at 10% to 90%.
• The product is not intended or labeled for once-daily seizure treatment.
• The dosage form does not produce the claimed release profile.
• The composition lacks a listed solubility-enhancing agent.
• The formulation does not satisfy the claimed MHD concentration limitations.

Invalidity theories

• Anticipation by earlier controlled-release oxcarbazepine formulations.
• Obviousness based on combining known hydrophilic matrices, surfactants, and enteric polymers.
• Lack of written description for the full numerical ranges or broad polymer classes.
• Enablement challenges directed to the breadth of the Markush group.
• Indefiniteness involving "homogeneous matrix," "sigmoidal" release, or PK ranges.
• Claim-category or dependency issues affecting claims 19 and 20.

The strongest invalidity arguments would likely require detailed review of the patent's cited references, prosecution history, examples, release-testing methods, and pre-filing formulation literature. The claim text alone does not establish whether those arguments would succeed.

What patent litigation and settlements affect this patent?

The principal litigation risk would arise when an ANDA applicant files a Paragraph IV certification against an Orange Book-listed patent. Under 21 U.S.C. § 355(j)(5)(B)(iii), a timely patent-infringement action can trigger a 30-month stay of FDA approval, subject to statutory exceptions and court orders. [4]

A complete litigation assessment should distinguish:

• Notice-letter litigation under 35 U.S.C. § 271(e)(2).
• Declaratory-judgment proceedings.
• Post-grant review or inter partes review.
• District-court claim-construction rulings.
• Consent judgments.
• Generic launch-at-risk events.
• Authorized-generic arrangements.
• Settlement agreements submitted under the Federal Trade Commission Act.

No settlement terms, dismissal, final judgment, or current ANDA challenge should be inferred from the patent claims. A patent may remain listed even if related litigation has ended, and a settlement may permit a generic launch before the listed patent's nominal expiration.

How strong is the patent estate?

US 9,119,791 has moderate-to-strong blocking value against a particular class of once-daily extended-release oxcarbazepine products, but it is not a complete monopoly over oxcarbazepine.

Strengths

• It combines formulation and method-of-treatment limitations.
• It covers several major excipient classes.
• The pH-dependent polymer list includes Eudragit L100-55, a commercially recognized enteric polymer.
• Claims 17-20 target the commercially important 600 mg tablet.
• Claims 14-16 add pharmacokinetic outcomes associated with reduced peak-trough fluctuation.

Weaknesses

• Claim 1 requires multiple limitations to be present simultaneously.
• The closed polymer list creates design-around opportunities.
• "Homogeneous matrix" may be difficult to apply to multiparticulate products.
• "Sigmoidal" release may depend on testing conditions and method definition.
• PK limitations may require patient or bioequivalence data that are difficult to establish from the dosage form alone.
• The claim set does not cover immediate-release oxcarbazepine generally.

The patent is best viewed as a formulation-specific barrier, not an active-ingredient patent.

How does this patent compare with competing oxcarbazepine protection?

Product or protection category	Relationship to US 9,119,791
Trileptal immediate-release oxcarbazepine	Generally outside the once-daily matrix claims
Generic immediate-release oxcarbazepine	Low direct exposure
Oxtellar XR	Primary commercial product associated with the claimed technology
Alternative once-daily matrix product	Potentially high exposure
Multiparticulate extended-release product	Depends on matrix and polymer construction
Oxcarbazepine product using a different release polymer	Potential design-around
MHD-based therapeutic method	Relevant only if the formulation and treatment limitations are met
Biosimilar product	Not applicable because oxcarbazepine is a small molecule

There is no biosimilar pathway for oxcarbazepine. Any follow-on product would proceed through the small-molecule ANDA or, in limited circumstances, a 505(b)(2) pathway. The central regulatory and patent issues would be bioequivalence, formulation similarity, labeling, and listed-patent certifications.

What manufacturing and geographic barriers matter?

The patent has United States territorial effect. It does not independently block manufacture, sale, or use outside the United States. Foreign equivalents, national-phase filings, continuations, and related applications must be analyzed separately in each jurisdiction.

Manufacturing risk is concentrated in the formulation process. A competitor may need to determine:

• Whether the active and polymer are co-granulated.
• Whether the matrix is homogeneous at the tablet or pellet level.
• Whether the pH-dependent polymer is incorporated internally or used as a coating.
• Whether the commercial batch falls within the claimed percentage ranges.
• Whether the release profile changes across pH stages.
• Whether the product's manufacturing records can establish or defeat infringement.

For ANDA litigation, discovery may reach development batches, master manufacturing records, excipient specifications, dissolution protocols, and bioequivalence data.

Key Takeaways

• US 9,119,791 protects a once-daily oxcarbazepine seizure-treatment formulation, not oxcarbazepine generally.
• Claim 1 requires a homogeneous matrix, a matrix polymer, a solubility enhancer, and a listed pH-dependent release polymer.
• The most exposed product is a 600 mg once-daily tablet using HPMC, a listed solubility enhancer, and Eudragit L100-55 or a comparable listed polymer.
• Immediate-release oxcarbazepine products are generally outside the core claim scope.
• The patent presents meaningful Paragraph IV risk but leaves potential design-around routes through polymer selection, dosage frequency, matrix structure, and formulation architecture.
• Claims 14-16 create additional enforcement complexity because they depend on MHD pharmacokinetic measurements.
• The patent's statutory expiration cannot be established from the grant date alone.
• Current Orange Book listing, litigation, settlement, and generic-entry status must be determined from FDA, USPTO, PACER, and FTC records rather than inferred from the claims.

FAQs

Does US 9,119,791 cover all extended-release oxcarbazepine products?

No. The product must satisfy the specific combination of once-daily administration, homogeneous matrix structure, quantitative excipient ranges, and a listed pH-dependent release polymer.

Can a generic avoid US 9,119,791 by using a different enteric polymer?

Potentially. The release-promoting polymer limitation uses a closed list, but equivalence, prosecution history, and other patent claims could affect the result.

Does the patent cover Trileptal?

The patent does not ordinarily cover immediate-release Trileptal because its independent claim requires a once-daily pharmaceutical formulation with the specified controlled-release matrix.

Are MHD concentration claims composition claims?

No. Claims 14-16 are dependent method claims requiring treatment with an amount of oxcarbazepine that produces specified MHD steady-state or peak-trough values.

Is a biosimilar required to challenge Oxtellar XR?

No. Oxcarbazepine is a small-molecule drug. A follow-on product would generally use the ANDA pathway, or potentially a 505(b)(2) application, rather than the biosimilar pathway.

References

1. U.S. Food and Drug Administration. (2012). Oxtellar XR prescribing information. https://www.accessdata.fda.gov
2. United States Patent and Trademark Office. (2015). U.S. Patent No. 9,119,791. https://patents.google.com/patent/US9119791
3. U.S. Food and Drug Administration. (n.d.). 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. 21 U.S.C. § 355(j); 35 U.S.C. § 271(e)(2).m

Drugs Protected by US Patent 9,119,791

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Supernus Pharms	OXTELLAR XR	oxcarbazepine	TABLET, EXTENDED RELEASE;ORAL	202810-001	Oct 19, 2012	AB	RX	Yes	No	9,119,791					TREATMENT OF PARTIAL-ONSET SEIZURES
Supernus Pharms	OXTELLAR XR	oxcarbazepine	TABLET, EXTENDED RELEASE;ORAL	202810-002	Oct 19, 2012	AB	RX	Yes	No	9,119,791					TREATMENT OF PARTIAL-ONSET SEIZURES
Supernus Pharms	OXTELLAR XR	oxcarbazepine	TABLET, EXTENDED RELEASE;ORAL	202810-003	Oct 19, 2012	AB	RX	Yes	Yes	9,119,791					TREATMENT OF PARTIAL-ONSET SEIZURES

International Family Members for US Patent 9,119,791

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	E496623
Australia	2007242984
Canada	2597740
China	101489560
Germany	602007012236
European Patent Office	2026815