U.S. Patent 8,486,947: Scope, Claims, Expiration, Orange Book Status, and Pitolisant Patent Landscape
U.S. Patent No. 8,486,947 protects methods of treating excessive daytime sleepiness with a defined class of histamine H3-receptor ligands, including pitolisant and specified salts, stereoisomers, hydrates, polymorphs and related analogs. The patent is a method-of-use patent, not the primary composition-of-matter patent for pitolisant. Its listed term expired on February 16, 2022, removing the patent as a current barrier to U.S. generic entry, subject to any separately enforceable continuation, later patent or regulatory exclusivity.
What does U.S. Patent 8,486,947 protect?
The patent protects administering compounds having the following core architecture:
Ar-(CH2)3-O-(CH2)3-NR1R2
The required structural elements are:
| Structural element |
Limitation in the claims |
| First carbon chain |
Unbranched propyl group, -(CH2)3- |
| Connecting atom |
Ether oxygen, -O- |
| Second carbon chain |
Unbranched propyl group containing three carbon atoms |
| Terminal amine |
Saturated nitrogen-containing ring or defined substituted amine |
| Aromatic group |
Phenyl ring, unsubstituted or substituted |
| Substituents |
Halogen, alkyl, carbonyl-related groups, oximes, aldehydes, ketones and other listed substituents |
| Therapeutic use |
Excessive daytime sleepiness |
| Named disease settings |
Parkinson's disease, narcolepsy or sleep apnea |
| Covered forms |
Salts, hydrates, hydrated salts, polymorphs, optical isomers, racemates, diastereomers and enantiomers |
The claim set is therefore broader than pitolisant alone. It covers a genus of H3-receptor ligands and then narrows through ring structure, substitution pattern, aromatic substitution and specific examples.
Claim 13 is the most commercially important species claim. It specifically identifies:
3-(4-chlorophenyl)propyl-3-piperidinopropyl ether
That compound is pitolisant, generally marketed as pitolisant hydrochloride under the brand name Wakix.
How broad is independent claim 1?
Claim 1 has two separate limitations that must be satisfied for literal infringement:
- The administered compound must fall within the defined formula IIa.
- The patient must have excessive daytime sleepiness associated with Parkinson's disease, narcolepsy or sleep apnea.
The structural limitation is broad because the phenyl group can be unsubstituted or substituted by numerous chemical groups. The claim also expressly extends to pharmaceutically acceptable salts, hydrates, hydrated salts, polymorphs and optical forms.
The disease limitation materially narrows the claim. Administration of a covered molecule for an unrelated indication would not literally satisfy the claimed method unless the use also falls within the stated treatment of excessive daytime sleepiness.
The claim does not require:
- A particular dose;
- A particular route of administration;
- A specific treatment duration;
- A particular formulation;
- A particular degree of improvement;
- Monotherapy;
- A specific age group; or
- A requirement that the compound be pitolisant hydrochloride.
These omissions increase the potential breadth of the method claim. A product label that directs use of a covered compound for excessive daytime sleepiness in a listed disease could create method-of-use exposure, depending on the patent term and other claim-construction issues.
Which claims specifically cover pitolisant?
Pitolisant is directly identified by the narrower claims.
| Claim |
Commercial relevance |
| Claim 1 |
Broad genus covering the structural class and listed diseases |
| Claims 2-9 |
Narrow the terminal amine to saturated nitrogen rings, including piperidine and pyrrolidine derivatives |
| Claims 10-11 |
Narrow aromatic substitution to halogenated and carbonyl or oxime-substituted phenyl compounds |
| Claim 12 |
Lists pitolisant-related analogs and stereochemical forms |
| Claim 13 |
Specifically covers 3-(4-chlorophenyl)propyl-3-piperidinopropyl ether, the pitolisant structure |
| Claim 14 |
Covers hydrochloride, hydrobromide, hydrogen maleate and hydrogen oxalate salts |
| Claim 15 |
Covers combination treatment with an H3 ligand and another medication |
| Claims 16-17 |
Narrow treatment to symptoms, including sleep and vigilance disorders |
| Claim 18 |
Identifies specified anti-Parkinson medicines for combination therapy |
Claim 13 is the clearest claim directed to pitolisant itself in a therapeutic method. Claim 14 is important for pitolisant hydrochloride, the marketed pharmaceutical form.
What formulations are protected by U.S. Patent 8,486,947?
The patent does not claim a detailed tablet, capsule or controlled-release formulation. It protects the active compound and certain pharmaceutical forms used in the claimed method.
The relevant protected forms include:
- Pitolisant free base;
- Pitolisant hydrochloride;
- Other listed pharmaceutically acceptable salts;
- Hydrates and hydrated salts;
- Polymorphic crystalline structures;
- Optical isomers;
- Racemates;
- Diastereomers; and
- Enantiomers.
This is different from a formulation patent directed to excipients, dissolution characteristics, particle size, coating, release profile or tablet composition. A later patent could cover those attributes independently, but U.S. Patent 8,486,947 itself does not require a particular excipient system or dosage form.
What method-of-use patents are covered by the patent?
The patent reaches several therapeutic-use categories.
Excessive daytime sleepiness
This is the central indication. The claims encompass treating excessive daytime sleepiness in patients with:
- Narcolepsy;
- Parkinson's disease; and
- Sleep apnea, including obstructive sleep apnea under the later claim language.
Sleep and vigilance symptoms
Claims 16 and 17 narrow the use to symptoms of Parkinson's disease, dementia with Lewy bodies and vascular dementia, including sleep and vigilance disorders.
Combination treatment
Claim 15 covers administration of an H3-receptor ligand with a medication used to treat a listed neurological disorder. Claim 18 identifies anti-Parkinson drugs, including levodopa, ropinirole, lisuride, bromocriptine and pramipexole.
The combination claims are narrower than claim 1 and require proof of both the H3-ligand administration and the specified combination therapy. They are less likely to reach a product label limited to pitolisant monotherapy for narcolepsy.
When did U.S. Patent 8,486,947 lose exclusivity?
The patent's listed expiration date was February 16, 2022. The patent originated from a priority chain associated with Bioprojet's H3-receptor ligand research and was granted on July 23, 2013. The relevant term was calculated from the earliest nonprovisional or international filing date used for U.S. patent-term purposes, rather than the earliest priority claim.
| Event |
Date |
| Earliest disclosed priority |
February 16, 2001 |
| International or equivalent filing period |
2002 |
| U.S. patent grant |
July 23, 2013 |
| Listed patent expiration |
February 16, 2022 |
| FDA approval of Wakix |
August 14, 2019 |
Expiration ended the ability to enforce the patent against new U.S. acts of infringement. It did not eliminate potential claims for infringement occurring before expiration. It also did not eliminate later patents directed to other pitolisant uses, formulations, dosing regimens or manufacturing processes.
What was the Orange Book status of U.S. Patent 8,486,947?
The patent was associated with the FDA-approved use of pitolisant for excessive daytime sleepiness in adult patients with narcolepsy. Wakix was approved by FDA in 2019 under NDA 211150 for adults with narcolepsy to treat excessive daytime sleepiness.
The patent's commercial function was to provide use protection after approval of the product. It was not the principal basis for a 20-year composition-of-matter monopoly because the patent claims methods of treatment rather than pitolisant as a chemical compound per se.
An Orange Book listing can delay approval of an ANDA through the Hatch-Waxman litigation process. After the listed patent expired, the patent no longer supplied a prospective statutory stay against approval. Later Orange Book-listed patents, if any, must be analyzed separately by patent number, use code and expiration date.
Were Paragraph IV challenges relevant to this patent?
A Paragraph IV certification is used when an ANDA applicant asserts that a listed patent is invalid, unenforceable or will not be infringed. For a method-of-use patent, an ANDA applicant can also rely on a section viii statement that it will carve out the patented use from the proposed labeling.
For U.S. Patent 8,486,947, the commercially relevant risk was a narrow-label strategy directed to non-patented uses or a Paragraph IV challenge before the February 2022 expiration date. Because the patent covered narcolepsy-related excessive daytime sleepiness, a carve-out would have had to avoid the protected indication while remaining acceptable to FDA.
The patent's expiration substantially reduced the value of a Paragraph IV challenge. The principal current generic-entry questions instead concern:
- Later pitolisant patents;
- FDA-approved labeling;
- Regulatory exclusivity;
- Non-infringing labeling;
- Product-specific formulation patents; and
- Manufacturing or process patents.
Which companies challenged the Wakix patent estate?
The major public patent disputes involving Wakix have focused on Harmony Biosciences' broader patent estate, including later patents directed to pitolisant formulations, dosing and treatment methods. Publicly reported ANDA litigation has involved generic applicants, including Teva Pharmaceuticals, in disputes over Wakix-related patents.
U.S. Patent 8,486,947 should not be treated as equivalent to every patent asserted in Wakix litigation. A litigation complaint may assert several patents with different claims, expiration dates and infringement theories. The 8,486,947 patent's expiration in 2022 makes it materially less important than later patents with terms extending into the 2030s.
How does U.S. Patent 8,486,947 compare with later Wakix patents?
| Patent category |
Typical protected subject matter |
Commercial effect |
| U.S. 8,486,947 |
Broad H3-ligand method of use for excessive daytime sleepiness and neurological disorders |
Expired in 2022 |
| Composition patents |
Pitolisant or related H3-ligand chemical structures |
Potentially stronger early exclusivity, depending on term |
| Formulation patents |
Tablets, salts, crystalline forms, excipients or dissolution properties |
Can restrict substitutable products after composition expiry |
| Dosing patents |
Titration, maintenance dosing or patient-selection methods |
Vulnerable to labeling carve-outs and claim-construction defenses |
| Later narcolepsy patents |
Treatment of excessive daytime sleepiness or cataplexy |
May remain relevant to ANDA approval |
| Manufacturing patents |
Synthetic routes, intermediates and purification |
Creates process risk but usually does not block a different lawful manufacturing route |
The patent is strongest as a historical use patent because it captures the use of a structurally defined class in several neurological conditions. It is weaker as a current commercial barrier because the term has expired and the claims do not cover every later formulation or manufacturing feature.
How strong is the patent estate for pitolisant?
The patent estate should be analyzed in layers:
- Composition-of-matter protection for pitolisant and related compounds.
- Salt and solid-state protection.
- Method-of-use protection for narcolepsy, excessive daytime sleepiness and cataplexy.
- Formulation protection.
- Manufacturing-process protection.
- Regulatory exclusivity and pediatric exclusivity.
U.S. Patent 8,486,947 provided broad historical use coverage but is no longer the principal blocking right. Later patents may create more meaningful entry risk if they cover the approved product's indication or cannot be carved out of an ANDA label.
The core generic-entry risk after expiration is therefore not infringement of 8,486,947. It is the possibility that a generic applicant must address later Orange Book-listed patents through Paragraph IV litigation, a section viii carve-out or a negotiated settlement.
What generic launch scenarios exist for pitolisant?
A generic applicant could pursue one of three principal strategies:
Full-label ANDA
The applicant seeks approval for the same indication as Wakix. This approach creates the highest risk of infringement allegations under later use patents.
Carved-out label
The applicant removes patented indications or dosing instructions under a section viii statement. This strategy is more difficult if the remaining label would not support a commercially viable product.
Paragraph IV challenge
The applicant certifies that later listed patents are invalid, unenforceable or not infringed. A timely patent suit can trigger a 30-month stay, subject to the statutory requirements and the status of each listed patent.
The expired 8,486,947 patent should not independently prevent approval of a properly filed generic application. It may remain relevant to historical damages or litigation over pre-expiration conduct, but not to ordinary post-expiration launch rights.
What is the geographic coverage of the patent?
U.S. Patent 8,486,947 has territorial effect only in the United States. Corresponding members of the same international patent family could have covered the compound or therapeutic use in Europe and other jurisdictions, but each national right required separate maintenance and had its own term.
A U.S. generic launch analysis must therefore be separated from:
- European Patent Office rights;
- United Kingdom rights;
- Canadian rights;
- Japanese rights;
- Australian rights; and
- Any national supplementary protection certificate or pediatric extension.
No foreign patent can independently block a U.S. sale.
Key Takeaways
- U.S. Patent 8,486,947 is a method-of-use patent for H3-receptor ligands treating excessive daytime sleepiness.
- Claim 13 specifically covers pitolisant, while claim 14 covers important salt forms, including hydrochloride.
- The patent covers narcolepsy, Parkinson's disease and sleep apnea-related treatment uses.
- It does not claim a detailed tablet formulation or a manufacturing process.
- The listed U.S. expiration date was February 16, 2022.
- The patent is no longer a prospective U.S. exclusivity barrier.
- Later Wakix patents, Orange Book listings, formulation rights, dosing patents and regulatory exclusivities determine current generic-entry risk.
- A generic applicant's principal options are a full-label ANDA, a section viii carve-out or a Paragraph IV challenge to later patents.
FAQs
Does U.S. Patent 8,486,947 claim pitolisant hydrochloride?
Yes. Claim 13 identifies the pitolisant molecular structure, and claim 14 covers pharmaceutically acceptable salts including hydrochloride.
Is U.S. Patent 8,486,947 a composition-of-matter patent?
No. Its claims are directed to methods of treating excessive daytime sleepiness using a defined class of compounds. It does not claim pitolisant as a standalone chemical composition in the conventional composition-of-matter format.
Can a generic market pitolisant after expiration of U.S. Patent 8,486,947?
Expiration removes this patent as a post-expiration infringement barrier. The generic must still address any later patents, FDA requirements, labeling restrictions and applicable regulatory exclusivity.
Does the patent cover pitolisant for cataplexy?
The supplied claims focus on excessive daytime sleepiness and the listed neurological disorders. They do not expressly recite cataplexy as an independent claimed condition. Cataplexy coverage must be assessed under later patents and the approved labeling.
Are pitolisant polymorphs and hydrates included?
Yes. The claims expressly extend to polymorphic crystalline structures, hydrates, hydrated salts and stereochemical forms of the covered compounds.
References
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U.S. Patent and Trademark Office. (2013). U.S. Patent No. 8,486,947, Use of H3 receptor ligands for treating excessive daytime sleepiness. U.S. Department of Commerce. https://patents.google.com/patent/US8486947B2/en
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U.S. Food and Drug Administration. (2019). Wakix (pitolisant hydrochloride) prescribing information. FDA. https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/211150s000lbl.pdf
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U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA. https://www.accessdata.fda.gov/scripts/cder/ob/
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U.S. Food and Drug Administration. (2024). Drugs@FDA: Wakix NDA 211150. FDA. https://www.accessdata.fda.gov/scripts/cder/daf/
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U.S. Food and Drug Administration. (2024). Approved drug product patent and exclusivity information. FDA. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-product-patent-and-exclusivity-information
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U.S. Code, 35 U.S.C. §§ 154, 271 and 355. Patent term, infringement and abbreviated new drug applications. https://uscode.house.gov/ાવ્યો
