US Patent 10,251,896: Claim Scope, Patent Strength, Exclusivity and Competitive Landscape

US Patent 10,251,896 protects a treatment method using a bile acid together with a phenylbutyric-acid compound for neurodegenerative disease. Its commercial scope is broad at the disease and compound-class level but narrower at the dosing and combination level. The principal enforceable value is concentrated in combinations of TUDCA or related bile acids with 4-PBA, particularly where the treatment is directed to oxidative stress, redox imbalance, or mitochondrial dysfunction.

The patent does not, based on the claims provided, cover a bile acid or PBA administered alone. It also does not create product exclusivity for TUDCA, UDCA, 4-PBA, glycerol phenylbutyrate, or the other listed compounds as standalone products.

What does US Patent 10,251,896 claim?

The independent claim requires all of the following:

A method of treating a neurodegenerative disease.
Administration of a specified bile acid or pharmaceutically acceptable salt.
Administration of a specified PBA compound or pharmaceutically acceptable salt.
A bile-acid dose of approximately 10 to 50 mg/kg.
A PBA dose of approximately 10 to 400 mg/kg.
Administration of amounts sufficient to treat the disease.

The listed bile acids are:

Tauroursodeoxycholic acid, or TUDCA
Ursodeoxycholic acid, or UDCA
Chenodeoxycholic acid
Cholic acid
Hyodeoxycholic acid
Lithocholic acid
Glycoursodeoxycholic acid

The listed PBA compounds are:

4-Phenylbutyric acid, or 4-PBA
Glycerol phenylbutyrate, commonly associated with tri-4-PBA
2-(4-Methoxyphenoxy)acetic acid, or 2-POAA-OMe
2-(4-Nitrophenoxy)acetic acid, or 2-POAA-NO2
2-(2-Naphthyloxy)acetic acid, or 2-NOAA

The dependent claims narrow the invention to mammals, humans, named neurodegenerative diseases, oxidative-stress mechanisms, mitochondrial dysfunction, TUDCA-equivalent dosing, 4-PBA dosing, separate or concurrent administration, and once-, twice-, or three-times-daily dosing. [1]

How broad is the independent claim?

Claim 1 is a combination-treatment claim with a large Markush structure. A treatment may fall within its literal scope if it uses any one listed bile acid and any one listed PBA compound within the stated dose ranges.

The claim therefore covers numerous pairings, including:

Bile acid	PBA compound	Potential claim status
TUDCA	4-PBA	Within claim 1 if dose limits are met
TUDCA	Glycerol phenylbutyrate	Within claim 1 if the compound is construed as the claimed PBA
UDCA	4-PBA	Within claim 1 if dose limits are met
UDCA	Glycerol phenylbutyrate	Within claim 1 if dose limits are met
Cholic acid	4-PBA	Within claim 1 if dose limits are met
Lithocholic acid	4-PBA	Within claim 1 if dose limits are met
TUDCA	2-POAA-OMe	Within claim 1 if dose limits are met
TUDCA	2-NOAA	Within claim 1 if dose limits are met

The claim does not require a fixed ratio between the bile acid and PBA. It does not require a particular formulation, route of administration, treatment duration, biomarker, disease stage, or clinical endpoint. It also does not require the compounds to be combined in one dosage form.

That structure increases potential coverage but creates validity and enforcement pressure. A challenger could argue that the claim combines known compounds across broad therapeutic and chemical classes without sufficient support for every claimed species and disease.

Which diseases are covered?

Claim 4 identifies the following diseases:

Multiple sclerosis
Alzheimer’s disease
Huntington’s disease
Parkinson’s disease
Amyotrophic lateral sclerosis
Pick’s disease
Multi-infarct dementia
Creutzfeldt-Jakob disease
Dementia with Lewy bodies
Mixed dementia
Frontotemporal dementia

The independent claim is not expressly limited to that list. Claim 4 narrows the scope to those named diseases, while claim 1 uses the broader term “neurodegenerative disease.”

This distinction matters in litigation. A defendant treating a disease outside the claim 4 list may still face exposure under claim 1 if the disease qualifies as a neurodegenerative disease and the other limitations are satisfied. Claim 4 is more specific but may be easier to defend against an enablement or written-description challenge for the listed conditions.

What mechanisms and biomarkers are protected?

Claims 5 through 9 define mechanistic and functional limitations:

Disease caused by oxidative stress or mitochondrial dysfunction
Reduction of reactive oxygen metabolite-mediated oxidative damage
Reduction of hydrogen-peroxide-mediated damage
Promotion of redox homeostasis
Reduction of mitochondrial dysfunction

These claims may be valuable in research and clinical settings where treatment records include biomarker evidence. They also create proof issues. A patent owner would need to establish that the accused method satisfies the relevant functional limitation, particularly where the claim requires treatment “in an amount sufficient” to produce a biological result.

Claims 6 through 9 are narrower than claim 1 because they require a particular biological effect. They may provide fallback positions if a court limits the broad disease-treatment claim.

What dose ranges are protected?

The principal dose ranges are:

Component	Broad claimed range	Narrower dependent range
Bile acid	About 10-50 mg/kg	TUDCA equivalent of about 10-30 mg/kg
PBA	About 10-400 mg/kg	4-PBA equivalent of about 10-100 mg/kg
PBA, further narrowed	About 30-100 mg/kg	4-PBA

Claims 10 through 12 are important because they focus the patent on TUDCA and 4-PBA, the combination most likely to be relevant to commercial development.

The word “about” creates a boundary issue. Courts generally assess the term in the context of the specification, prosecution history, measurement method, and technical meaning. A dosing regimen slightly outside the stated range may still be disputed if it is technically equivalent, but a materially different dose provides a stronger noninfringement position.

The claims use mg/kg of body weight. A product label expressed in total daily grams would require conversion based on patient weight and dosing frequency. Divided daily doses can still fall within the claims if the total administered amount satisfies the relevant interpretation of the range.

Does the patent cover a fixed-dose combination product?

No fixed-dose combination is required.

Claim 13 covers separate administration. Claim 14 covers concurrent administration. The patent therefore reaches:

Two separate oral products taken together
Sequential administration during the same treatment regimen
A single co-formulated dosage form
Separate products administered at the same time
Separate products administered at different times, subject to claim construction

Claim 15 covers once-daily, twice-daily, and three-times-daily administration. It does not require any specific dosage form, release profile, excipient, capsule, tablet, liquid, infusion, or delivery device.

A formulation company could face method-of-use exposure even if its product formulation is independently novel. Conversely, a formulation patent would not necessarily block practice of the patented method if the formulation does not satisfy the claimed dose or compound limitations.

How strong is the patent estate?

The patent’s strength is mixed.

Stronger features

The most defensible commercial scope is likely:

TUDCA plus 4-PBA
Human treatment
Alzheimer’s disease, Parkinson’s disease, ALS, or another expressly identified condition
Doses within the narrower TUDCA and 4-PBA ranges
Concurrent or repeated administration
A documented oxidative-stress or mitochondrial-dysfunction endpoint

These limitations provide a more concrete infringement theory than the broad class-level claim.

Weaker features

The broadest claim has several vulnerability points:

It covers seven bile acids and five PBA compounds.
It extends across numerous neurodegenerative diseases.
It does not require a specific formulation or route.
It does not establish a fixed ratio or treatment duration.
It relies on broad functional language such as “sufficient to treat.”
The listed compounds have differing pharmacology, tolerability, metabolism, and clinical development status.

A validity challenge could focus on anticipation, obviousness, written description, enablement, indefiniteness, or lack of predictable results across the full genus. Under US patent law, a broad genus claim can be vulnerable where the disclosure does not reasonably support or enable the full claimed scope. [4]

The narrow TUDCA/4-PBA claims may have greater practical value if the specification reports combination data showing an unexpected effect, synergy, improved mitochondrial function, or superior oxidative-stress control compared with either agent alone.

What prior-art issues affect validity?

The relevant prior-art field contains several overlapping categories:

Prior-art category	Relevance
TUDCA and UDCA therapy	Establishes known bile-acid pharmacology and uses
4-PBA therapy	Establishes PBA’s known use as a chemical chaperone, ammonia-scavenging agent, and stress-response modulator
Sodium phenylbutyrate and glycerol phenylbutyrate	Establishes clinical dosing, formulations, and regulatory history
Neurodegenerative-disease use of TUDCA	May affect novelty or obviousness for bile-acid treatment
Neurodegenerative-disease use of PBA	May affect novelty or obviousness for PBA treatment
Combination therapy references	Most important prior art against claim 1
Oxidative-stress and mitochondrial-function studies	Relevant to the mechanistic dependent claims
Formulation and salt patents	Relevant to product design but not necessarily to the method claims

The central validity question is whether a skilled person would have been motivated to combine a bile acid and PBA for neurodegenerative disease, with a reasonable expectation of success, at the claimed dose ranges. Evidence of synergy or an unexpected result would support patentability. Broad experimental claims unsupported by disease-specific data would create risk.

What is the FDA status of the relevant compounds?

The compounds do not have equivalent regulatory positions.

Compound	FDA position relevant to this analysis
UDCA	Approved as ursodiol for specified hepatobiliary indications
4-PBA	Approved as sodium phenylbutyrate for urea-cycle disorders
Glycerol phenylbutyrate	Approved as RAVICTI for urea-cycle disorders
TUDCA	No widely established FDA-approved therapeutic product for the claimed neurodegenerative indications
2-POAA-OMe, 2-POAA-NO2, 2-NOAA	No comparable FDA-approved status identified in the claim set

BUPHENYL and RAVICTI approvals do not authorize the claimed neurodegenerative uses. FDA approval for a compound in one indication does not eliminate method-of-use patent risk in another indication. [2, 3]

What is the Orange Book status?

The patent claims supplied are method-of-treatment claims covering combinations for neurodegenerative disease. They are not, by themselves, evidence that the patent is listed in the FDA Orange Book.

The Orange Book generally lists patents submitted for approved drug products and approved uses, including qualifying drug-substance, drug-product, and method-of-use patents. A patent directed to an unapproved TUDCA/PBA neurodegenerative combination would not automatically qualify for listing against BUPHENYL, RAVICTI, or an ursodiol product. [5]

The practical result is:

No automatic Orange Book barrier to a generic 4-PBA or glycerol phenylbutyrate product for its existing approved indication.
Potential regulatory-patent exposure if a sponsor seeks approval for a covered neurodegenerative use.
Potential litigation under a Paragraph IV certification if the patent is listed against a relevant approved drug and method of use.

Are Paragraph IV challenges likely?

A Paragraph IV challenge would be relevant only if the patent is listed in the Orange Book for a reference product and the ANDA applicant seeks approval for a use covered by the listed patent.

For this patent, a Paragraph IV pathway is less straightforward because:

The claimed combination includes compounds that may not be the reference product.
TUDCA is not the active ingredient in BUPHENYL or RAVICTI.
The patent covers neurodegenerative uses rather than the approved urea-cycle indications of phenylbutyrate products.
A generic applicant may use a section viii statement to omit a patented method from its label where permitted.
A commercial launch involving promotion, labeling, or physician instructions for the covered combination could still create infringement exposure.

The more likely challenge route for a company developing a TUDCA/PBA product is a declaratory judgment, inter partes review where available, or district-court invalidity defense rather than a conventional ANDA dispute.

What generic and biosimilar entry risks exist?

This is a small-molecule patent. Biosimilar procedures do not apply.

Generic-entry risk divides into three scenarios:

Generic 4-PBA or glycerol phenylbutyrate for existing indications

A generic product for urea-cycle disorders would not necessarily practice the patent. Risk increases only if the product label, promotional activity, or actual use targets a claimed neurodegenerative combination.

New 4-PBA product for neurodegenerative disease

A sponsor developing 4-PBA for ALS, Parkinson’s disease, Alzheimer’s disease, or another covered condition could face the patent if it also administers a listed bile acid within the claimed range.

TUDCA/PBA combination product

This is the highest-risk scenario because it directly maps onto claim 1. The sponsor would need to evaluate literal infringement, doctrine-of-equivalents risk, validity, freedom to operate, and possible licensing.

What patent landscape surrounds TUDCA and PBA?

The landscape is fragmented across four patent themes:

Compound and salt protection for bile acids and PBA derivatives.
Formulation protection for oral, liquid, delayed-release, and combination products.
Method-of-use protection for neurological, metabolic, hepatic, and mitochondrial disorders.
Manufacturing and purification protection.

US Patent 10,251,896 is most relevant to the fourth category of use: administering the two classes together for neurodegenerative disease.

It does not appear, from the claims supplied, to claim:

A new chemical entity
A specific crystalline form
A particular polymorph
A defined excipient system
A sustained-release composition
A manufacturing process
A biomarker-defined patient population
A specific fixed ratio
A particular route such as intrathecal or intravenous delivery

Those areas may support separate patent protection and could create layered freedom-to-operate barriers even if US 10,251,896 is invalidated or expires.

When does US Patent 10,251,896 lose exclusivity?

The exact expiration date cannot be calculated from the issued claims alone. US utility patents generally expire 20 years from the effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and applicable priority rules. The issue date, April 9, 2019, does not determine the expiration date. [1, 6]

The relevant diligence points are:

Exclusivity item	Assessment
Patent type	US utility patent
Patent number	10,251,896
Issue date	April 9, 2019
Ordinary term	20 years from effective nonprovisional filing date
PTA/PTE	Must be checked in the USPTO record
Orange Book exclusivity	Not established by the claims
FDA regulatory exclusivity	Not created by this patent
Biosimilar exclusivity	Not applicable

Regulatory exclusivity is separate from patent exclusivity. FDA orphan-drug, new-chemical-entity, clinical-investigation, or pediatric exclusivity would depend on a later product approval and would not arise solely from this patent. [7]

What litigation and licensing issues affect the patent?

The principal litigation theory would be method infringement under 35 U.S.C. § 271, including direct infringement by practicing the treatment method and possible induced infringement through labeling, protocols, investigator instructions, or promotional materials. [6]

The most important evidence would include:

The prescribed or administered compounds
Patient weight and dose calculations
Treatment frequency
Whether both agents were administered
Disease indication
Product labeling and promotional materials
Clinical protocols
Biomarker results for oxidative stress or mitochondrial dysfunction
Physician and sponsor intent

No licensing arrangement is established by the claims provided. A commercial developer would likely seek either a license for a direct TUDCA/4-PBA program or a covenant not to sue, particularly if the program uses the narrower TUDCA and 4-PBA dose ranges.

Key Takeaways

US 10,251,896 is a combination method patent, not a standalone product patent.
Its core coverage is a bile acid plus a PBA compound for neurodegenerative disease.
TUDCA plus 4-PBA is the clearest commercial embodiment.
Claims 10 through 12 provide narrower protection around TUDCA and 4-PBA dosing.
Separate, concurrent, and up to three-times-daily administration are expressly covered.
The patent does not require a fixed-dose combination, specific formulation, route, or treatment duration.
Broad genus coverage creates potential written-description, enablement, obviousness, and indefiniteness challenges.
BUPHENYL and RAVICTI approvals do not authorize the claimed neurodegenerative uses.
The patent does not automatically create an Orange Book barrier for existing phenylbutyrate products.
Biosimilar law is irrelevant because the claimed products are small molecules.
Exact patent expiry requires the effective filing date and any PTA, PTE, or terminal-disclaimer information.

FAQs

Does US 10,251,896 cover TUDCA alone?

No. The asserted method must administer both a listed bile acid and a listed PBA compound within the claim limitations.

Does taking UDCA and sodium phenylbutyrate potentially infringe?

Yes, if the treatment is for a covered neurodegenerative disease and the administered amounts fall within the claim’s dose ranges or a narrower applicable claim.

Does the patent cover RAVICTI?

It can cover a method using glycerol phenylbutyrate if the other claim elements are satisfied. The patent does not claim RAVICTI as a product.

Can a company avoid the patent by administering the two drugs at different times?

Not necessarily. Claim 13 expressly addresses separate administration, while claim 14 addresses concurrent administration. The timing and regimen would require claim-specific analysis.

Is a clinical trial using TUDCA and 4-PBA automatically blocked?

No. Clinical-trial activity, research exemptions, investigator conduct, sponsor instructions, and commercial promotion raise different legal issues. A trial protocol that practices the claimed method can still create patent risk, particularly outside any applicable statutory exemption.

Sources

United States Patent and Trademark Office. (2019). U.S. Patent No. 10,251,896, methods of treating neurodegenerative disease.
U.S. Food and Drug Administration. (n.d.). BUPHENYL (sodium phenylbutyrate) prescribing information.
U.S. Food and Drug Administration. (n.d.). RAVICTI (glycerol phenylbutyrate) prescribing information.
United States Patent and Trademark Office. (2023). Manual of Patent Examining Procedure, including written description, enablement, obviousness, and claim-construction principles.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
35 U.S.C. §§ 154, 271, 282.
U.S. Food and Drug Administration. (n.d.). Small business and industry assistance: Exclusivity and patent provisions.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Amylyx	RELYVRIO	sodium phenylbutyrate; taurursodiol	FOR SUSPENSION;ORAL	216660-001	Sep 29, 2022		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial				TREATMENT OF AMYOTROPHIC LATERAL SCLEROSIS (ALS) IN ADULTS	⤷ 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	2014242123	⤷ Start Trial
Australia	2019200658	⤷ Start Trial
Australia	2021201770	⤷ Start Trial
Australia	2022221410	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,251,896

Which drugs does patent 10,251,896 protect, and when does it expire?

Summary for Patent: 10,251,896