Generic entry timeline

Dayvigo generics — when can they launch?

Dayvigo (LEMBOREXANT) · Eisai · 8 active US patents · 0 expired

Earliest patent expiry

2031-09-20

5 years remaining

Full patent estate to

2035-10-21

complete protection through 2035

FDA approval

2019

Eisai

Where Dayvigo sits in the generic timeline

Mid-term cliff: earliest active US patent for Dayvigo expires in 2031 (~5 years). Generic developers typically begin ANDA bioequivalence studies 3-4 years ahead of this date. Paragraph IV filings + Hatch-Waxman 30-month stays may shift the effective entry by another 18-36 months.

Under US Hatch-Waxman, a generic enters via an ANDA (Abbreviated New Drug Application) and may file with one of four Paragraph IV certifications attacking the brand's listed patents. If the brand sues within 45 days, a 30-month FDA approval stay is triggered. First Para IV filer typically gets 180-day market exclusivity.

Patent estate by type — active patents

Method-of-use patents only carve out specific indications; generics can launch with a "skinny label" omitting those uses. Composition-of-matter patents block the molecule itself.

Method of Use — 4 patents
Formulation — 4 patents

FDA U-codes carved out by Dayvigo patents

Method-of-use patents are listed against specific FDA Patent Use Codes ("U-codes") representing carved-out indications. Generics can launch with a label that omits these uses.

U-code	Description
`U-2791`	(no description)

Sample patent estate

Showing 6 of 8 active US patents. View full estate on the Dayvigo drug page →

US8268848 Method of Use · expires 2031-09-20

USPTO title: Cyclopropane compound
US8268848 Method of Use · expires 2031-09-20

USPTO title: Cyclopropane compound
US10702529 Formulation · expires 2035-10-21

This patent protects compositions and methods for treating insomnia using a specific compound as an orexin receptor antagonist.

USPTO title: Compositions and methods for treating insomnia
US11026944 Formulation · expires 2035-10-21

This patent protects compositions and methods for treating insomnia using a specific compound as an orexin receptor antagonist.

USPTO title: Compositions and methods for treating insomnia
US10188652 Method of Use · expires 2035-10-21

This patent protects compositions and methods for treating insomnia using a specific compound as an orexin receptor antagonist.

USPTO title: Compositions and methods for treating insomnia
US10188652 Method of Use · expires 2035-10-21

This patent protects compositions and methods for treating insomnia using a specific compound as an orexin receptor antagonist.

USPTO title: Compositions and methods for treating insomnia

Sources

FDA Orange Book — patents listed against Dayvigo (NDA filed 2019)
Dayvigo drug profile — full patent estate, indications, clinical trials, pricing
Eisai patent portfolio
Patent cliff 2031 — every drug losing US exclusivity that year

Patent term extensions (PTR, pediatric exclusivity), Hatch-Waxman 30-month stays, and FDA regulatory exclusivity (NCE/ODE/PED) may shift the effective generic entry date. Not legal advice.

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