US Patent 10,478,442: Fenfluramine and Stiripentol Combination Patent Analysis

US Patent 10,478,442 protects a narrow treatment protocol for Dravet syndrome involving fenfluramine administered with stiripentol. Its strongest commercial relevance is the low-dose fenfluramine regimen used when Fintepla is coadministered with stiripentol and clobazam. The patent does not broadly cover fenfluramine, stiripentol, Fintepla, or all Dravet syndrome treatments.

The patent issued on November 19, 2019, and is listed in FDA Orange Book records with an expiration date of June 27, 2035.[1][2] The claims are method-of-treatment claims, so the principal enforcement targets are manufacturers, prescribers, specialty pharmacies, health systems, and patients or caregivers whose coordinated conduct may satisfy the claimed treatment steps.

What does US Patent 10,478,442 cover?

The patent covers administering fenfluramine together with stiripentol to treat seizures in a patient with Dravet syndrome, with specific claims directed to a daily fenfluramine dose of 0.2 mg/kg/day.

Claim	Principal limitation	Scope
1	Dravet syndrome; fenfluramine at 0.2 mg/kg/day; stiripentol; seizure amelioration	Core combination-treatment claim
2	Same treatment, plus a patient exhibiting a gene mutation	Genotype-linked treatment claim
3	Claim 2 limited to eight listed genes	Narrower genetic subgenus
4	Determine that the patient has a Dravet-associated mutation, then administer both drugs	Patient-selection and treatment claim
5	Claim 4 limited to eight listed genes	Narrower diagnostic-selection claim
6	Dravet syndrome; fenfluramine within a stated dose range; stiripentol; seizure amelioration	Dose-range combination claim

The protected combination is:

Fenfluramine or a pharmaceutically acceptable salt;
Stiripentol or a pharmaceutically acceptable salt;
A patient diagnosed with Dravet syndrome, for the principal claims;
Adjunctive seizure treatment;
Fenfluramine administered at or around 0.2 mg/kg/day for the principal claims; and
Seizure amelioration.

The claims do not require a particular formulation, route of administration, age, treatment duration, seizure subtype, response threshold, or stiripentol dose, except that stiripentol must be administered at an “effective dose.”

How should the US 10,478,442 claims be construed?

Claim 1 is the principal commercial claim

Claim 1 requires a patient diagnosed with Dravet syndrome to receive both fenfluramine and stiripentol. It is the broadest independent claim because it does not require genetic testing or a specific mutation.

The fenfluramine limitation is dose-specific. A regimen that uses materially less or more than 0.2 mg/kg/day may fall outside the literal scope of claim 1, subject to claim construction and possible doctrine-of-equivalents arguments. The claim uses “0.2 mg/kg/day,” which ordinarily describes the total daily dose normalized to body weight.

Claim 1 does not require clobazam. That matters because the FDA-approved Dravet syndrome use of stiripentol is generally associated with concomitant clobazam, while the patent claim itself requires only stiripentol.[3]

Claims 2 and 3 add genetic limitations

Claim 2 requires the patient to exhibit a mutation in a gene, but does not identify the gene in the independent claim. Claim 3 limits the mutation to one of eight genes:

SCN1A
SCN1B
SCN2A
SCN3A
SCN9A
GABRG2
GABRD
PCDH19

SCN1A is the most commercially important gene in this list because pathogenic SCN1A variants are strongly associated with Dravet syndrome. Claims 2 and 3 may be difficult to practice without genetic information, but the claims do not expressly require that the mutation be proven to be pathogenic, causal, germline, de novo, or heterozygous.

Claims 4 and 5 require a determination step

Claims 4 and 5 require determining that the patient has a mutation associated with Dravet syndrome before administering fenfluramine and stiripentol.

This creates a factual infringement issue. A genetic test performed by a laboratory, followed by treatment prescribed by a neurologist, may involve multiple actors. Liability would depend on how the steps are attributed under US divided-infringement principles and whether one party directs or controls the complete method.[4]

The “associated with Dravet syndrome” language in claim 4 is broader than the eight-gene list in claim 5. Claim 4 could cover mutations outside the listed genes if they are shown to be associated with Dravet syndrome, while claim 5 is limited to the enumerated genes.

Claim 6 contains a material drafting issue

As supplied, claim 6 recites fenfluramine administered in a dose of “0.5 mg/kg/day to 0.2 mg/kg/day.” Read literally, that range is reversed because 0.5 is greater than 0.2.

The likely intended range may have been 0.05 mg/kg/day to 0.2 mg/kg/day, which would be consistent with low-dose fenfluramine dosing used with stiripentol. The issued patent record, prosecution history, certificate of correction record, and claim construction would control whether the wording can be corrected or otherwise interpreted. On the claim text provided, the range has an internal numerical inconsistency and creates a substantial validity and enforceability issue for claim 6.

What dose does the patent protect?

The commercial center of gravity is the 0.2 mg/kg/day fenfluramine dose used with stiripentol.

Fintepla labeling provides a maximum recommended dosage of 0.2 mg/kg/day when fenfluramine is administered with stiripentol and clobazam. The corresponding maximum without stiripentol is higher.[3]

Treatment context	Patent relevance	FDA label relevance
Fenfluramine alone	Generally outside claims 1-6 because stiripentol is required	Approved for Dravet syndrome and Lennox-Gastaut syndrome
Fenfluramine plus stiripentol	Core patent territory	Low-dose regimen is label-relevant
Fenfluramine plus stiripentol plus clobazam	Core patent territory	Particularly important because this is the labeled stiripentol regimen
Stiripentol without fenfluramine	Outside the claims	Diacomit-approved treatment context
Fenfluramine above 0.2 mg/kg/day with stiripentol	Potentially outside literal claims 1-5	May conflict with labeled maximum dosing
Fenfluramine below 0.2 mg/kg/day with stiripentol	Potentially outside claim 1, depending on claim 6 construction	May still be clinically used during titration

The patent therefore aligns closely with the low-dose coadministration protocol rather than with the broader Fintepla product label.

What patents protect Fintepla and the fenfluramine product?

US Patent 10,478,442 is one layer of the Fintepla patent estate. It protects a clinical use combination rather than the active ingredient itself.

Product and formulation protection

A complete Fintepla freedom-to-operate analysis must distinguish:

Fenfluramine active-ingredient patents;
Fenfluramine hydrochloride composition claims;
Oral solution formulation claims;
Stability and pharmaceutical composition claims;
Container and dosing-device claims;
Dravet syndrome method-of-use claims;
Lennox-Gastaut syndrome method-of-use claims;
Combination claims involving stiripentol or clobazam;
Pediatric dosing and titration claims.

US 10,478,442 does not expressly claim the Fintepla oral solution, a particular concentration, an excipient system, a bottle, a syringe, or a manufacturing process. A competing manufacturer could therefore avoid this patent in principle by using a different clinical regimen, but that would not eliminate exposure under separate product, formulation, or method patents.

Manufacturing and formulation barriers

The patent creates no direct manufacturing barrier. It does not claim:

Synthesis of fenfluramine;
Synthesis of stiripentol;
Purification of either active ingredient;
Preparation of fenfluramine hydrochloride;
A specific oral-solution formulation;
A particular analytical specification;
A device for dispensing the product.

The main barrier is use of the combination regimen in the United States. A generic fenfluramine product could face a separate regulatory and patent challenge if its proposed labeling instructs use with stiripentol for Dravet syndrome.

When does US Patent 10,478,442 lose exclusivity?

Event	Date or status
Earliest priority date reported for the patent family	June 27, 2014
Patent grant	November 19, 2019
Orange Book patent expiration date	June 27, 2035
Patent term status	Unexpired as reflected in the cited FDA records
Pediatric exclusivity	Product-specific regulatory exclusivity must be analyzed separately
US market impact	Combination-method protection may continue after other Fintepla patents expire

The June 27, 2035 expiration date is the relevant Orange Book date for the patent listing. A patent’s enforceability can be affected by terminal disclaimers, patent-term adjustment, disclaimer filings, reexamination, post-grant proceedings, or litigation outcomes. The Orange Book listing is the operative regulatory reference for ANDA certification analysis.[2]

What is the Orange Book status of US 10,478,442?

The patent is listed for Fintepla in the FDA Orange Book as a patent relevant to the approved drug product and its use.[2] Its commercial importance is greater than its claim count suggests because an ANDA applicant seeking approval for fenfluramine with labeling that includes the patented combination may need to address the listing through a Paragraph IV certification.

The listing does not mean every fenfluramine product infringes. The relevant question is whether the proposed ANDA labeling would induce use of fenfluramine with stiripentol in the claimed patient population and dose.

A product designed for a non-infringing indication or regimen could present a different analysis, but labeling cannot be evaluated separately from foreseeable physician prescribing, product instructions, and other Orange Book patents.

Which companies are challenging US 10,478,442?

No publicly reported Paragraph IV litigation against this patent is identified in the supplied record. The absence of reported litigation does not establish that no ANDA certification has been filed, because FDA certification activity and patent litigation can occur on different timelines.

The principal potential challengers would be generic pharmaceutical companies seeking approval for:

Fenfluramine hydrochloride oral solution;
A therapeutic equivalent to Fintepla;
A product labeled for Dravet syndrome;
A product whose labeling includes dosing with stiripentol.

Potential litigation theories would include:

Invalidity based on anticipation or obviousness;
Lack of written description or enablement;
Indefiniteness, particularly concerning “effective dose” and the reversed range in claim 6;
Noninfringement based on dose, diagnosis, labeling, or absence of stiripentol;
Failure of the patent claims to cover the applicant’s proposed labeling.

How strong is the patent estate for the fenfluramine-stiripentol combination?

The estate is commercially meaningful but technically narrow.

Strength factor	Assessment
Alignment with labeled dosing	Strong for the 0.2 mg/kg/day stiripentol regimen
Disease specificity	Strong; claims are limited principally to Dravet syndrome
Combination requirement	Limits scope but directly targets an important clinical use
Formulation coverage in this patent	None apparent from the supplied claims
Genetic claims	Potentially useful but narrower and dependent on testing evidence
Dose flexibility	Limited for claims 1-5; claim 6 has a numerical drafting problem
Manufacturing protection	None apparent
Generic-label exposure	Material if the ANDA label instructs coadministration with stiripentol
Biosimilar exposure	Not applicable because Fintepla is a small-molecule drug
Geographic scope	United States only

The strongest claim is likely claim 1 because it avoids the additional genetic-testing requirements in claims 2-5. Its weakness is the fixed 0.2 mg/kg/day limitation. The patent does not cover every dose of fenfluramine used with stiripentol.

Claims 2-5 may provide fallback protection if genetic testing is routinely performed and documented, but they create proof burdens. The patent owner would need to establish the mutation, the relevant diagnosis or association with Dravet syndrome, the administration of both drugs, and seizure amelioration.

What Paragraph IV and generic-launch risks exist?

A generic applicant could pursue several launch strategies.

Strategy 1: Challenge the patent directly

The applicant could file a Paragraph IV certification asserting that the patent is invalid, unenforceable, or not infringed. A timely infringement action by the patent owner could trigger the Hatch-Waxman 30-month stay, subject to statutory exceptions and court rulings.[5]

Strategy 2: Omit the patented combination from labeling

A generic applicant could attempt a section viii carve-out or other labeling strategy that omits use with stiripentol. This approach would reduce exposure to US 10,478,442 but could conflict with other use patents or with FDA requirements for a complete, non-misleading label.

Strategy 3: Avoid the claimed dose

A product label could avoid the 0.2 mg/kg/day regimen. This strategy is complicated by the clinical importance of the low-dose regimen and by potential claim 6 coverage if the corrected range is interpreted as 0.05 to 0.2 mg/kg/day.

Strategy 4: Launch after patent expiry

Absent a successful challenge or design-around, the clearest date for unrestricted launch against this listed patent is after June 27, 2035. Earlier entry could occur through settlement, license, judgment, or successful noninfringement strategy.

What litigation and settlement issues affect the patent?

The patent’s principal litigation risks are claim-specific rather than product-wide.

A litigation complaint would likely focus on whether the accused labeling:

Identifies Dravet syndrome;
Recommends or instructs use with stiripentol;
Specifies a fenfluramine dose of 0.2 mg/kg/day;
Instructs treatment of patients who have relevant mutations;
Encourages seizure treatment that satisfies the “ameliorated” limitation.

Settlement terms could permit an agreed generic entry date before June 27, 2035, subject to antitrust scrutiny and the terms of the settlement. No publicly reported settlement affecting US Patent 10,478,442 is identified in the supplied record.

How does US 10,478,442 compare with competing-drug patent estates?

Product	Active ingredient	Drug type	Biosimilar issue	Relevance to US 10,478,442
Fintepla	Fenfluramine hydrochloride	Small molecule	No	Directly implicated
Diacomit	Stiripentol	Small molecule	No	Required combination component
Epidiolex	Cannabidiol	Small molecule	No	Competing Dravet treatment; separate estate
Depakote and related valproate products	Valproate compounds	Small molecule	No	Broad epilepsy competition
Briviact	Brivaracetam	Small molecule	No	Alternative antiseizure therapy
Diacomit plus fenfluramine	Stiripentol plus fenfluramine	Combination regimen	No	Core claimed use

There is no biosimilar pathway for Fintepla because fenfluramine is a small-molecule active ingredient. Competition will arise through ANDAs, 505(b)(2) applications, off-label prescribing, and alternative antiseizure products rather than biosimilar applications.[6]

What is the commercial exposure associated with this patent?

Jazz Pharmaceuticals acquired Zogenix in 2022 for approximately $1.1 billion, with Fintepla as a principal commercial asset.[7] The patent’s revenue exposure is therefore tied to Fintepla sales in Dravet syndrome, particularly patients receiving stiripentol-based adjunctive therapy.

The patent does not cover the entire Fintepla market. Patients treated without stiripentol, patients treated for Lennox-Gastaut syndrome, and patients receiving doses outside the claimed regimen may fall outside US 10,478,442. Separate patents and regulatory exclusivities may still protect those markets.

What geographic coverage does US 10,478,442 provide?

The patent has territorial effect only in the United States. It does not establish protection in Europe, Japan, China, Canada, or other jurisdictions.

Foreign protection must be assessed through the corresponding PCT and national-phase family members. The US claims should not be assumed to match foreign claims because national prosecution can produce different disease, dosing, genotype, and combination limitations.

Key Takeaways

US Patent 10,478,442 is a US method-of-treatment patent for fenfluramine plus stiripentol in Dravet syndrome.
The core dose limitation is 0.2 mg/kg/day of fenfluramine.
Claim 1 is the broadest and most commercially important claim.
Claims 2-5 add mutation and genetic-testing limitations, with eight genes identified in dependent claims.
The patent does not claim fenfluramine composition, Fintepla oral solution, stiripentol manufacture, or a manufacturing process.
The Orange Book expiration date is June 27, 2035.
Fintepla is a small molecule, so biosimilar risk is not applicable.
Generic risk is concentrated in ANDA labeling that instructs fenfluramine use with stiripentol for Dravet syndrome.
Claim 6, as supplied, contains a reversed dose range of 0.5 to 0.2 mg/kg/day and presents a material claim-construction issue.
No publicly reported Paragraph IV litigation or settlement affecting this patent is identified in the supplied record.
The patent is important for a specific clinical segment, but it does not by itself block all fenfluramine competition.

FAQs About US Patent 10,478,442

Does US Patent 10,478,442 cover Fintepla for all Dravet syndrome patients?

No. The claims require coadministration of fenfluramine with stiripentol. Fintepla treatment without stiripentol is outside the literal scope of the principal claims.

Does the patent require clobazam?

No. The claims require stiripentol but do not require clobazam. Clobazam may be clinically relevant to the FDA-labeled stiripentol regimen, but it is not a stated patent limitation.

Can a generic avoid the patent by using a different fenfluramine dose?

Potentially, but the result depends on the final construction of the claims and the scope of claim 6. Claims 1-5 expressly focus on 0.2 mg/kg/day, while claim 6 contains the reversed range quoted in the question.

Are SCN1A mutations required for infringement?

No. Claim 1 does not require a genetic mutation. SCN1A and the other listed genes become relevant only to the narrower genetic claims.

Does the patent protect treatment outside the United States?

No. US Patent 10,478,442 is enforceable only in the United States. Foreign counterparts require separate jurisdiction-by-jurisdiction analysis.

Sources

United States Patent and Trademark Office. (2019). U.S. Patent No. 10,478,442, methods of treating Dravet syndrome.
U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations, Orange Book: Fintepla.
U.S. Food and Drug Administration. (2024). Fintepla (fenfluramine) oral solution prescribing information.
United States Court of Appeals for the Federal Circuit. (2015). Akamai Technologies, Inc. v. Limelight Networks, Inc., 797 F.3d 1020.
U.S. Food and Drug Administration. (2024). Abbreviated new drug application approvals and patent certifications under the Hatch-Waxman Act.
U.S. Food and Drug Administration. (2024). Biosimilar and interchangeable biosimilar products.
Jazz Pharmaceuticals plc. (2022). Jazz Pharmaceuticals completes acquisition of GW Pharmaceuticals and Zogenix-related corporate filings.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Ucb Inc	FINTEPLA	fenfluramine hydrochloride	SOLUTION;ORAL	212102-001	Jun 25, 2020		RX	Yes	Yes	10,478,442*PED	⤷ Start Trial			Y		⤷ 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	2014261329	⤷ Start Trial
Australia	2019203448	⤷ Start Trial
Australia	2019203832	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,478,442

Which drugs does patent 10,478,442 protect, and when does it expire?

Summary for Patent: 10,478,442