DAYVIGO Drug Patent Profile

When do Dayvigo patents expire, and what generic alternatives are available?

Dayvigo is a drug marketed by Eisai Inc and is included in one NDA. There are four patents protecting this drug and one Paragraph IV challenge.

The generic ingredient in DAYVIGO is lemborexant. One supplier is listed for this compound. Additional details are available on the lemborexant profile page.

DrugPatentWatch^® Generic Entry Outlook for Dayvigo

Dayvigo was eligible for patent challenges on April 7, 2024.

By analyzing the patents and regulatory protections it appears that the earliest date for generic entry will be October 21, 2035. This may change due to patent challenges or generic licensing.

There is one Paragraph IV patent challenge for this drug. This may lead to patent invalidation or a license for generic production.

Indicators of Generic Entry

Summary for DAYVIGO

US Patents:	4
Applicants:	1
NDAs:	1

Paragraph IV (Patent) Challenges for DAYVIGO

Tradename	Dosage	Ingredient	Strength	NDA	ANDAs Submitted	Submissiondate
DAYVIGO	Tablets	lemborexant	5 mg	212028	1	2026-07-14

US Patents and Regulatory Information for DAYVIGO

DAYVIGO is protected by four US patents and one FDA Regulatory Exclusivity.

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Eisai Inc	DAYVIGO	lemborexant	TABLET;ORAL	212028-001	Apr 7, 2020		RX	Yes	No			Y	Y
Eisai Inc	DAYVIGO	lemborexant	TABLET;ORAL	212028-002	Apr 7, 2020		RX	Yes	Yes			Y	Y
Eisai Inc	DAYVIGO	lemborexant	TABLET;ORAL	212028-001	Apr 7, 2020		RX	Yes	No			Y

International Patents for DAYVIGO

When does loss-of-exclusivity occur for DAYVIGO?

Based on analysis by DrugPatentWatch, the following patents block generic entry in the countries listed below:

Australia

Brazil

Canada

China

European Patent Office

Israel

Japan

Mexico

Russian Federation

Singapore

South Korea

Spain

Generics may enter earlier, or later, based on new patent filings, patent extensions, patent invalidation, early generic licensing, generic entry preferences, and other factors.

See the table below for additional patents covering DAYVIGO around the world.

Country	Patent Number	Title	Estimated Expiration
Australia	2015336463
Brazil	112017007063
Canada	2964504

Dayvigo (lemborexant) Investment Scenario and Patent-to-Commercial Fundamentals (2026)

Last updated: July 27, 2026

Executive summary: Dayvigo (lemborexant) is an Eisai sleep franchise asset with FDA approval in adults for insomnia, generating revenue exposure to 2020s payer pressure, class competition from other orexin antagonists, and exclusivity risk tied to patent term and potential generic or “at-risk” entry timing. The investment case hinges on (1) whether orexin-antagonist demand continues to shift to lemborexant versus suvorexant and other comparators, (2) the pace of new competitors and formulary tightening, and (3) the strength and enforceability of Dayvigo’s patent estate across key oral solid dosage forms and any extended-protection changes.

---

What is Dayvigo (lemborexant) and how is it positioned commercially?

Dayvigo (lemborexant) is an orexin receptor antagonist for treatment of insomnia in adults. The commercial thesis for investors is that lemborexant targets the orexin pathway with a differentiated efficacy-tolerability profile versus older hypnotics, supporting formulary pull and repeat prescribing.

Key market positioning variables

• Indication breadth within insomnia (adult patient population under the approved label)
• Dosing convenience (tablet dosing regimen depends on the approved label)
• Clinical positioning versus:
  • Other orexin antagonists: suvorexant (Belsomra, Merck) and alternative agents in the class
  • Non-orexin hypnotics: Z-drugs, benzodiazepines, and related sedative-hypnotics
• Payer behavior: step edits, prior authorization, and preferential formulary placement for select orexin antagonists

Commercial drivers investors typically underwrite

• Script growth rate and share capture within insomnia treatment
• Retention (treatment persistence) and adherence to the label
• Net price trend and rebate intensity from Medicare Part D, Medicaid managed care, and commercial PBMs
• Cannibalization and share migration within the orexin antagonist segment

---

How do Dayvigo’s competitors affect lemborexant revenue risk?

Orexin antagonist peer set

• Belsomra (suvorexant): direct orexin antagonist competitor
• Other orexin-targeting agents: risk includes substitution during formulary decisions and prescriber switching

What drives substitution

• Formulary status by PBM and integrated delivery networks
• Clinical messaging and head-to-head outcomes in insomnia populations
• Safety and next-day impairment perception, prescriber familiarity, and patient preference
• Patient switching costs: stable responders tend to remain, but payer edits accelerate switches

Revenue exposure framework

• If Dayvigo loses formulary status to a peer orexin antagonist, revenue risk is typically sharp due to high switching elasticity after coverage changes.
• If Dayvigo maintains “preferred” status within the class, risk trends toward gradual erosion from incremental competition rather than abrupt volume declines.

---

What is the FDA and Orange Book status of Dayvigo (lemborexant)?

Regulatory milestone structure investors focus on

• NDA approval and listed patents in the FDA Orange Book
• Supplemental NDA changes that can add patent listings (including formulation or method claims)
• Exclusivity listings:
  • Hatch-Waxman patent term extension (PTE) where applicable
  • Non-patent exclusivities (if present for the specific NDA or supplement)

Orange Book-driven diligence

• Identify:
  • Active ingredient(s): lemborexant
  • Drug product(s): dose forms and strengths
  • Listed patents by use and formulation
  • Expiration dates by patent number
• Then map:
  • Which patents are “but-for” barriers for a generic or 505(b)(2) entrant
  • Whether any listed patents are likely to be the subject of Paragraph IV challenges

(Orange Book listing details were not provided in the prompt. Without listing-level patent numbers and dates, a complete and accurate patent-to-date exclusivity schedule cannot be constructed in this response.)

---

When does Dayvigo lose exclusivity and what are the generic entry timing risks?

Exclusivity depends on two layers

1. Patent term (including any PTE and patent expiration by listed patent)
2. Regulatory exclusivities (if any were granted to the NDA)

Investment timing logic

• If the relevant listed patents expire earlier than any PTE-enhanced barrier, generic launch risk can shift earlier.
• If patent coverage extends through multiple “core” patents across dosage forms or methods-of-use, entry is less likely to be complete and may remain design-around-driven.

Typical investor scenarios

• Base case: Continued branded dominance within insomnia while peer orexin competition caps growth and pricing.
• Bear case: One or more high-impact listed patents face an invalidity or non-infringement posture in Paragraph IV litigation, allowing earlier generic entry or authorized 505(b)(2) competition.
• Upside case: Patent estate sustains a longer “thicket” and settlement agreements delay market entry beyond the earliest theoretical expiration.

(A precise exclusivity and generic launch timeline cannot be produced without Orange Book patent numbers and expiration dates.)

---

How strong is the patent estate for Dayvigo (lemborexant)?

How to underwrite “patent estate strength”

• Coverage density: number of Orange Book-listed patents per drug product
• Legal fragility:
  • Composition of matter strength vs. dependent formulation/method claims
  • Claim breadth and vulnerability to design-arounds
• Practical enforceability:
  • Whether patents map cleanly to product structure and approved dosing
  • Whether competitors can launch with alternative formulations or manufacturing processes

What investors need to see in the record

• Patents are commonly grouped into:
  • Core active ingredient claims (composition)
  • Salt/polymorph or crystal form claims
  • Formulation claims (immediate-release oral tablets, excipient systems, coating systems)
  • Method-of-use claims (insomnia treatment, specific dosing regimen)

(Without Orange Book listing data or specific patent numbers, a complete patent-strength scoring model cannot be calculated here.)

---

What patents protect lemborexant formulations and dosing regimens?

Typical formulation and product-scoped coverage

• Tablet composition and excipient selection
• Dissolution profile and release characteristics
• Solid-state properties affecting bioavailability and PK
• Manufacturing process claims that can be used as injunction leverage

Dosing and method-of-use coverage

• Claims tying orexin antagonism to insomnia endpoints
• Dose timing and patient selection features (as supported by label and clinical data)

(Again, the prompt does not include Orange Book patent numbers or formulation-specific listings for Dayvigo.)

---

What patent litigation affects Dayvigo (lemborexant) and how does it shape settlement risk?

Litigation impact channels

• Patent infringement findings and injunction outcomes
• Settlement agreements:
  • Carve-outs tied to approval timing
  • Delayed launch dates for generics
  • Licensing terms for certain entrants or limited product scopes
• Brand-to-brand settlement dynamics (authorized entrants with negotiated exclusivity windows)

Investor questions tied to litigation

• Which patents were asserted and which were dismissed
• Whether the court stayed matters pending appeal
• Whether a final judgment changed the expected entry date

(No litigation docket details were provided; a complete litigation map cannot be stated accurately.)

---

Are there Paragraph IV ANDA or 505(b)(2) challenges for Dayvigo?

What Paragraph IV challenges usually signal

• A generics company believes it can:
  • Not infringe or invalidate a listed patent
  • Launch at a risk date while fighting remaining litigation
• The NDA holder faces:
  • Infringement posture and settlement leverage
  • Market share loss if at-risk launch occurs

What investors track

• Notice dates
• Asserted patents
• Section viii carve-outs and “skinny” labels
• The presence of first-filer exclusivity and forfeiture triggers

(No Paragraph IV notice data was included in the prompt; this response cannot list specific challengers or dates.)

---

What is the biosimilar or biologics angle for Dayvigo?

Dayvigo is a small-molecule oral drug, so biosimilar frameworks are not applicable. The relevant generic framework is ANDA/505(b)(2) under Hatch-Waxman.

---

How does Dayvigo compare with Belsomra (suvorexant) for market share and payer acceptance?

Competitive comparison lenses

• Prescriber switching behavior after a coverage decision
• Patient-reported next-day impairment and sleep quality durability
• PBM formulary tiers and step therapy rules for insomnia drugs
• Brand awareness and detailing intensity

Investment read-across

• If the market views the class as interchangeable, volume is more sensitive to price and tier placement.
• If lemborexant has better persistence outcomes in real-world settings, it can defend share even in competitive formularies.

(No real-world claims or payer formulary datasets were provided, so no quantitative share and persistence analysis is included.)

---

What are the manufacturing and IP barriers for generic lemborexant?

Potential IP and technical barriers

• Tablet formulation and dissolution characteristics that maintain therapeutic exposure
• Manufacturing controls that preserve bioequivalence across scale-up
• Solid-state form control if covered by patents
• Stability and shelf-life constraints affecting generic product feasibility

Regulatory barrier

• ANDA requires demonstrating bioequivalence to the reference listed drug
• If certain patents block ANDA approval or delay final approval, launch timing can shift even after submission

(No product development or ANDA technical detail was provided.)

---

Investment scenario analysis: bull, base, bear cases for Dayvigo (lemborexant)

Bull case

• Dayvigo sustains preferred formulary status versus orexin competitors.
• Pricing erosion is slower than peers, with manageable rebate pressure.
• Patent estate and any litigation outcomes extend practical exclusivity and delay generic launch.
• Growth is supported by ongoing physician adoption and high persistence.

Base case

• Moderate share gains or stable share in a growing insomnia market segment.
• Payer pressure reduces net pricing but maintains volumes.
• Generic/alternative competition begins after expected patent/potential settlement delays, with partial brand erosion rather than abrupt drop.

Bear case

• Tier downgrade or strict step edits reduce prescriptions.
• Orexin peer competitors capture formulary preference.
• High-impact patents are invalidated or designed around, triggering earlier than expected competitive erosion.

(A quantified financial forecast is not produced because the prompt did not include Dayvigo revenue, segment financials, or market share metrics.)

---

Key patent-and-regulatory diligence checklist for an investment decision

1. Orange Book:
   • Listed patents by dosage form and strength
   • Patent expiration and any PTE-adjusted dates
2. Exclusivity:
   • Any non-patent exclusivities tied to the NDA or supplements
3. Litigation and notices:
   • Paragraph IV filings, asserted patents, and litigation outcomes
4. Settlement:
   • Any negotiated entry dates, launch restrictions, or licensing terms
5. Competitive landscape:
   • Orexin class peer formulary status and pricing dynamics
6. Formulation and manufacturing:
   • Whether generics must design around formulation-specific barriers

(This checklist identifies the correct diligence fields but cannot supply the underlying Dayvigo dates and patent numbers.)

---

Key Takeaways

• Dayvigo’s investment profile depends on branded share retention under payer pressure and the practical durability of its patent estate rather than label-level clinical efficacy alone.
• The risk window for generic entry is driven by Orange Book-listed patents and any litigation/settlement delays; these specifics must be mapped to precise expiration dates to underwrite timing.
• Near-term upside is constrained primarily by orexin-class competition, while downside is driven by formulary tier changes and any earlier-than-expected patent clearance.

---

FAQs

1. What is the fastest likely path for generic lemborexant entry under Hatch-Waxman?
2. How do payer step edits for insomnia drugs change prescription volumes for orexin antagonists?
3. What patent types most often block ANDA approval for oral small-molecule insomnia drugs?
4. How does real-world persistence with lemborexant affect long-term branded revenue compared with suvorexant?
5. What deal structures are most common in insomnia drug patent settlements (launch dates, carve-outs, licensing)?

---

References (APA)

1. FDA. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. U.S. Food and Drug Administration. https://www.accessdata.fda.gov/scripts/cder/daf/
2. FDA. Drugs@FDA. U.S. Food and Drug Administration. https://www.accessdata.fda.gov/scripts/cder/daf/