United States Patent 10,702,529: Scope, Claim Analysis, Exclusivity and Patent Landscape for Lemborexant

U.S. Patent No. 10,702,529 protects oral once-daily dosage forms of lemborexant, marketed as Dayvigo, when the dosage form produces specified human pharmacokinetic exposure. The patent does not broadly claim the lemborexant molecule, every lemborexant formulation, or every use of lemborexant. Its central limitation is a dose-and-exposure relationship covering 2.5 mg to 10 mg once-daily products.

The patent is commercially important because it targets the approved Dayvigo dosing range and uses pharmacokinetic limitations that may complicate generic substitution even where the generic contains the same active ingredient.

What drug does U.S. Patent 10,702,529 cover?

Compound A is lemborexant, an orexin receptor antagonist with activity at both OX1R and OX2R. The chemical name in the claims is:

(1R,2S)-2-(((2,4-dimethylpyrimidin-5-yl)oxy)methyl)-2-(3-fluorophenyl)-N-(5-fluoropyridin-2-yl)cyclopropanecarboxamide.

Lemborexant is approved by the FDA under NDA 212028 as Dayvigo for the treatment of insomnia characterized by difficulties with sleep onset and/or sleep maintenance. The approved strengths are 5 mg and 10 mg tablets administered once nightly immediately before bedtime, with at least seven hours remaining before planned awakening (FDA, 2019).

The patent therefore relates directly to the commercial product and its approved dose strengths.

Patent identification

Item	Details
U.S. patent	10,702,529
Patent type	Pharmaceutical dosage form and pharmacokinetic exposure patent
Active ingredient	Lemborexant
Commercial product	Dayvigo
Relevant dosage range	2.5 mg to 10 mg once daily
FDA-approved strengths	5 mg and 10 mg
Core protection	Dose forms producing defined Cmax and AUC exposure
Issuance	July 7, 2020
Listed Orange Book expiration	March 17, 2037, subject to applicable statutory adjustments
Patent holder/commercial sponsor	Eisai Co., Ltd. and affiliated entities

The expiration date is the Orange Book-listed date associated with the Dayvigo patent listing and should be distinguished from the ordinary calculation based only on the issue date. The patent term generally derives from the earliest effective nonprovisional filing date, subject to patent-term adjustment and other statutory provisions (USPTO, 2024; FDA, 2024a).

What does claim 1 of U.S. Patent 10,702,529 protect?

Claim 1 has four principal limitations:

An oral dosage form.
A therapeutically effective amount of lemborexant.
A single daily dose of approximately 2.5 mg to approximately 10 mg.
Human pharmacokinetic performance within specified Cmax limits.

The claim requires a mean Cmax of approximately 3.0 ng/mL to approximately 7.2 ng/mL for each 1 mg of lemborexant after administration to human subjects.

On a simple dose-normalized basis, claim 1 corresponds to the following exposure ranges:

Dose	Approximate Cmax range under claim 1
2.5 mg	7.5 to 18.0 ng/mL
5 mg	15.0 to 36.0 ng/mL
10 mg	30.0 to 72.0 ng/mL

The word "comprising" makes the claim open-ended as to excipients. A product may contain additional excipients, coatings, disintegrants, binders, lubricants, surfactants or release modifiers without falling outside the claim solely because of those ingredients.

The claim is narrower than a composition claim covering any tablet containing lemborexant. A competing product must satisfy both the structural limitation, meaning lemborexant in an oral dosage form, and the claimed clinical exposure limitation.

How do claims 2 through 13 narrow the patent scope?

Claims 2 through 13 add dose-specific or exposure-specific limitations. The dependent claims concentrate on the FDA-approved 5 mg and 10 mg strengths.

Cmax claims

Claim	Dose	Required mean Cmax
1	2.5-10 mg	3.0-7.2 ng/mL per mg
2	5 mg	80%-125% of 23 ng/mL, or 18.4-28.75 ng/mL
3	10 mg	80%-125% of 36 ng/mL, or 28.8-45.0 ng/mL

Claims 2 and 3 are narrower than claim 1 because they require a specific dose and a specific reference exposure. They also create a potential claim-construction issue: the 10 mg range in claim 3 extends below and above some values that could be calculated from claim 1, but the dependent claim is interpreted together with claim 1. The narrower claim is likely intended to identify the observed clinical exposure for the marketed strengths.

AUC(0-24) claims

Claim	Dose	Required mean AUC(0-24)
4	2.5-10 mg	15.9-23.8 ng·hr/mL per mg
5	5 mg	80%-125% of 95 ng·hr/mL, or 76.0-118.75 ng·hr/mL
6	10 mg	80%-125% of 159 ng·hr/mL, or 127.2-198.75 ng·hr/mL

AUC(0-24) measures exposure from dosing through 24 hours. Claims 4 through 6 may be particularly relevant to a generic developer because a formulation can have an acceptable Cmax but fall outside the claimed AUC range, or satisfy the AUC limitation while producing a different peak concentration.

AUC(0-t) claims

Claim	Dose	Required mean AUC(0-t)
7	2.5-10 mg	19.1-51.1 ng·hr/mL per mg
8	5 mg	80%-125% of 128 ng·hr/mL, or 102.4-160.0 ng·hr/mL
9	10 mg	80%-125% of 284 ng·hr/mL, or 227.2-355.0 ng·hr/mL

AUC(0-t) measures exposure through the last quantifiable concentration. It is analytically different from AUC(0-24) and AUC(0-inf). The use of multiple AUC definitions increases the number of potential infringement theories but also creates dependence on study design, sampling duration and bioanalytical handling.

AUC(0-inf) claims

Claim	Dose	Required mean AUC(0-inf)
10	2.5-10 mg	19.8-53.1 ng·hr/mL per mg
11	5 mg	80%-125% of 149 ng·hr/mL, or 119.2-186.25 ng·hr/mL
12	10 mg	80%-125% of 311 ng·hr/mL, or 248.8-388.75 ng·hr/mL

AUC(0-inf) includes an extrapolated terminal component. This may make the limitation more sensitive to terminal half-life estimation and the percentage of AUC extrapolated beyond the last measured concentration.

Claim 13: late plasma concentration

Claim 13 requires a mean plasma lemborexant concentration of approximately 20 ng/mL or less at 8 to 10 hours after administration. This claim is directed to late exposure rather than only peak or total exposure.

The limitation may reflect an effort to maintain hypnotic efficacy while limiting next-day residual concentrations. It could be important in an infringement analysis because two products with similar Cmax and AUC values may produce different late-phase concentrations due to differences in dissolution, absorption rate or distribution.

What is the strongest patent claim?

Claim 1 is the broadest claim and the principal commercial claim. Its strengths are:

It covers the approved 5 mg and 10 mg doses.
It covers an oral dosage form rather than a narrowly defined tablet composition.
It uses an open-ended excipient limitation.
It captures products through pharmacokinetic performance, not only formulation ingredients.
It may reach nonidentical formulations that reproduce the claimed exposure profile.

Claims 2 through 12 provide fallback positions tied to specific clinical exposure values. Claim 13 provides another fallback position based on late plasma concentration.

The principal weakness is that the claims depend on pharmacokinetic results in human subjects. Infringement may require reliable clinical or bioequivalence data rather than inspection of the product label or qualitative analysis of the tablet. The scope may also depend on the meaning of "mean," "about," study conditions, fed or fasted state, sampling schedule, assay variability and the population used to generate the result.

What formulation characteristics are protected?

The patent does not require a particular excipient, manufacturing process, particle size, polymorph, coating or dissolution profile in the claims provided. It protects the finished oral dosage form when the form produces the specified exposure.

Potentially relevant formulation variables include:

Lemborexant particle size and solid-state form.
Tablet hardness and disintegration time.
Wet or dry granulation.
Binder and disintegrant selection.
Film coating.
Lubricant concentration.
Dissolution rate.
Food-effect behavior.
Absorption rate and terminal elimination.
Dose uniformity between 5 mg and 10 mg strengths.

A formulation that uses different excipients may still fall within the claims. Conversely, a formulation with the same excipients may avoid a particular dependent claim if its clinical exposure falls outside the specified range, although it could still infringe another claim.

Does the patent cover methods of use?

The claims supplied are dosage-form claims, not conventional method-of-treatment claims. They do not expressly recite treating insomnia, administering to a patient with insomnia, or improving sleep onset or sleep maintenance.

The patent can still affect a generic product intended for insomnia treatment because the product may be sold with a label corresponding to the patented dosage form. Under Hatch-Waxman, a generic applicant generally must address listed patents through a Paragraph IV certification, a statement that the patent is not infringed, invalid or unenforceable, or a certification that the applicant will wait until patent expiration (FDA, 2024b).

The patent should therefore be analyzed separately from earlier lemborexant composition-of-matter patents and any method-of-treatment or dosing patents.

What is the Orange Book status of U.S. Patent 10,702,529?

FDA Orange Book listings identify patents that the NDA holder represents as covering the approved drug, its formulation or an approved method of use. U.S. Patent 10,702,529 is listed for Dayvigo and is associated with a March 17, 2037 expiration date in the Orange Book patent table (FDA, 2024a).

The listing has three commercial effects:

An ANDA applicant must address the patent.
A Paragraph IV notice can trigger patent litigation under 21 U.S.C. § 355(j).
A timely infringement action can create a statutory 30-month stay of ANDA approval, subject to the Hatch-Waxman framework.

An Orange Book listing does not establish validity or infringement. It identifies the patent as one that the NDA holder believes is relevant to the approved product.

When does Dayvigo lose exclusivity?

Dayvigo has several different exclusivity concepts:

Exclusivity type	Relevance
New chemical entity exclusivity	FDA approval began in 2019; the NCE period is separate from patent term
Orphan exclusivity	Dayvigo is not generally treated as an orphan-drug product
Patent exclusivity	U.S. Patent 10,702,529 is listed through March 17, 2037
Data exclusivity	Regulatory exclusivity does not necessarily end on the same date as the patent
Pediatric exclusivity	Any six-month pediatric extension would depend on FDA-granted pediatric protection

The practical generic-entry date may be earlier than March 17, 2037 if a Paragraph IV challenge succeeds, a settlement permits an earlier launch, the patent is disclaimed or delisted, or a court determines that the patent is not infringed or is invalid.

What Paragraph IV risks exist for a generic lemborexant product?

A generic applicant could challenge the patent on several grounds.

Noninfringement

The applicant may argue that its product does not produce the claimed mean Cmax, AUC or late plasma concentration. This strategy is difficult if the ANDA relies on bioequivalence to Dayvigo because the generic product may inherently reproduce similar exposure.

The applicant could instead develop a formulation with a materially different pharmacokinetic profile, but that approach may create regulatory problems if the product fails the required bioequivalence standard.

Invalidity for indefiniteness

Potential issues include:

The meaning of "about."
The statistical meaning of "mean."
Whether the claims define a required study population.
Whether food state or fasting state is required.
The meaning of "after administration to human subjects."
Whether the sampling schedule is sufficiently specified.
How to evaluate AUC(0-t) when the terminal concentration is not measurable.
Whether claim 13's "at from 8 to 10 hours" identifies one time point or a time interval.

The claims use conventional pharmacokinetic terminology, which may support enforceability, but the absence of detailed test conditions could create litigation issues.

Written description and enablement

A challenger could argue that the patent does not adequately support the full 2.5 mg to 10 mg range or all combinations of dose, Cmax and AUC. The patentee would rely on clinical pharmacology data and the disclosure of the lemborexant dosage forms.

Obviousness

A challenger could combine prior art disclosing lemborexant, once-daily dosing, 5 mg and 10 mg clinical doses, and pharmacokinetic results. The central question would be whether the claimed exposure ranges were an inventive formulation result or an expected consequence of administering known doses of a known molecule.

Pharmacokinetic claims can be vulnerable when they merely describe inherent properties of a prior-art product. They are stronger when the exposure profile results from a nonobvious formulation or an unexpected dose-response relationship.

Which companies are challenging the Dayvigo patent?

No publicly identified commercial biosimilar challenge is relevant because lemborexant is a small-molecule drug and generic competition would proceed through the ANDA pathway, not the biosimilar pathway.

A public Orange Book listing does not disclose every ANDA filing or Paragraph IV notice. Unless an NDA holder files an infringement action, a generic applicant's identity and certification may remain confidential. No widely reported U.S. Paragraph IV litigation involving Patent 10,702,529 is identified in the cited public regulatory materials.

The absence of reported litigation does not eliminate future challenge risk. The patent's 2037 expiration date creates a long period during which an ANDA applicant could pursue an early invalidity or noninfringement strategy.

How does this patent compare with earlier lemborexant patents?

The Dayvigo patent estate can be divided into four technical layers:

Patent layer	Typical protection	Commercial importance
Composition of matter	Lemborexant and related chemical compounds	Broadest molecule-level protection
Solid-state and formulation	Polymorphs, salts, tablets, excipients and dissolution	Product-specific protection
Pharmacokinetic dosage form	Dose and human Cmax/AUC relationships	Protects marketed exposure profile
Medical use and dosing	Insomnia treatment, timing and patient administration	Supports label-based enforcement

U.S. Patent 10,702,529 is strongest against a generic that closely follows the Dayvigo dose and bioequivalence profile. It is less directly relevant to a different delivery system that produces substantially different exposure and is not required to match the Dayvigo pharmacokinetic profile.

What is the geographic coverage?

The patent provides protection only in the United States. Equivalent patent family members may exist in Japan, Europe, Canada, China, Australia and other jurisdictions, but their claim scope, expiration dates, prosecution history and enforceability must be assessed separately.

The U.S. patent does not prevent manufacture or sale outside the United States unless another jurisdiction has corresponding enforceable rights. U.S. importation, commercial manufacture, sale, offer for sale and certain activities related to ANDA development can create separate infringement questions under 35 U.S.C. §§ 271(a), 271(e) and related provisions.

What manufacturing and IP barriers remain after patent expiration?

Patent expiration will not automatically eliminate every market barrier. A generic entrant may still need to address:

FDA ANDA approval.
Bioequivalence to Dayvigo.
Tablet dose uniformity.
Stability and impurity controls.
Lemborexant solid-state characterization.
Manufacturing-scale dissolution performance.
Labeling and substitutability requirements.
Any unexpired formulation, method-of-use or regulatory exclusivity rights.

The key distinction is between a product that is chemically equivalent and a product that satisfies the patented exposure limitations. For Dayvigo, the regulatory requirement for bioequivalence may align closely with the patent's pharmacokinetic limitations, increasing the practical value of the patent even if individual claims face litigation vulnerabilities.

Key Takeaways

U.S. Patent 10,702,529 covers oral once-daily lemborexant dosage forms producing specified human pharmacokinetic exposure.
The patent directly targets the approved 5 mg and 10 mg Dayvigo strengths.
Claim 1 is the broadest claim; claims 2 through 12 add dose-specific Cmax and AUC limitations, while claim 13 covers late plasma concentration.
The claims do not require a specific excipient or manufacturing process.
The patent is listed in the Orange Book for Dayvigo with a March 17, 2037 expiration date.
Generic competition would proceed through the ANDA and Paragraph IV framework, not the biosimilar pathway.
The main litigation issues are likely to involve pharmacokinetic claim construction, inherency, obviousness, enablement, indefiniteness and the relationship between bioequivalence and infringement.
The patent is one layer of the broader lemborexant estate, which may also include composition, formulation, solid-state and use patents.

FAQs

Can a generic avoid U.S. Patent 10,702,529 by using different excipients?

Not necessarily. The claims are open-ended and do not require a particular excipient set. A product using different excipients may still infringe if it contains lemborexant in an oral dosage form and produces the claimed exposure.

Does a 5 mg generic tablet necessarily infringe the 5 mg claims?

No. Dose alone is insufficient. The product must also satisfy the relevant Cmax or AUC limitation, measured under an appropriate human pharmacokinetic analysis.

Is U.S. Patent 10,702,529 a composition-of-matter patent?

No. The claims provided are dosage-form claims limited by dose and pharmacokinetic performance. They do not broadly claim all lemborexant molecules or all compositions containing lemborexant.

Could a controlled-release lemborexant product avoid this patent?

Possibly, but only if its exposure profile falls outside the asserted claims and the product does not infringe other Dayvigo patents. A different release profile could also create FDA bioequivalence and labeling issues.

Does patent expiration guarantee immediate generic Dayvigo substitution?

No. FDA approval, ANDA requirements, bioequivalence, manufacturing readiness, state substitution rules and any other unexpired patents or regulatory exclusivities can affect the launch date.

References

Eisai Co., Ltd. (2019). Dayvigo (lemborexant) tablets, prescribing information. U.S. Food and Drug Administration.
U.S. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
U.S. Food and Drug Administration. (2024b). Abbreviated new drug application process and patent certifications. FDA.
U.S. Patent and Trademark Office. (2024). Patent term adjustment and patent term calculation guidance. U.S. Department of Commerce.
U.S. Patent No. 10,702,529. (2020). Oral dosage forms comprising lemborexant with defined pharmacokinetic exposure. U.S. Patent and Trademark Office.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Eisai Inc	DAYVIGO	lemborexant	TABLET;ORAL	212028-001	Apr 7, 2020		RX	Yes	No	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
Eisai Inc	DAYVIGO	lemborexant	TABLET;ORAL	212028-002	Apr 7, 2020		RX	Yes	Yes	⤷ Start Trial	⤷ 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	2015336463	⤷ Start Trial
Brazil	112017007063	⤷ Start Trial
Canada	2964504	⤷ Start Trial
China	107810006	⤷ Start Trial
European Patent Office	3209298	⤷ Start Trial
Spain	2843952	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,702,529

Which drugs does patent 10,702,529 protect, and when does it expire?

Summary for Patent: 10,702,529