United States Patent 10,653,662: Doxepin Insomnia Claims, Scope, Expiration, and Patent Landscape

United States Patent No. 10,653,662 protects a narrow method of treating sleep-maintenance insomnia with low-dose oral doxepin. The independent claim requires four core elements: doxepin administration, a 1-to-7 mg dose, administration before bedtime, and difficulty remaining asleep during the final portion of an intended eight-hour sleep period. The patent does not broadly cover doxepin, doxepin hydrochloride, tablets, capsules, or the manufacture of doxepin products.

The commercially important claim positions are the 3 mg and 6 mg regimens, which correspond to the approved Silenor strengths. The patent is a method-of-use asset. Its infringement risk is highest where a product label or prescribing materials direct use for sleep-maintenance insomnia in the claimed dose range.

What does United States Patent 10,653,662 cover?

Patent 10,653,662 covers administering low-dose doxepin to a patient with a specific sleep-maintenance problem: difficulty staying asleep near the end of an intended eight-hour sleep period.[1]

The central limitation is temporal. The patient must have difficulty remaining asleep during the final 60 minutes of the desired sleep period. Dependent claims narrow that period to the final 45 or 30 minutes.

The patent does not claim all insomnia treatment. It is directed to a defined patient population and use pattern:

Required limitation in claim 1	Scope
Disease or condition	Insomnia or a sleep disorder
Sleep phenotype	Difficulty staying asleep during the final 60 minutes of an intended eight-hour sleep period
Active ingredient	Doxepin or a pharmaceutically acceptable salt
Dose	About 1 mg to about 7 mg
Dosage form	Oral formulation
Timing	Before bedtime

The claim language creates a cumulative test. A potentially infringing use must satisfy each limitation. A doxepin product used for sleep initiation, for example, would not necessarily meet the claimed final-60-minute sleep-maintenance limitation.

How do claims 1 through 17 divide the patent scope?

Claims 1 through 17 form a method-of-treatment claim set with dosage-form, dose, timing, age, and sleep-period limitations.

Claim	Principal limitation	Commercial significance
1	Oral doxepin, about 1-7 mg, before bedtime, for final-60-minute sleep-maintenance difficulty	Broadest independent claim
2	Improved insomnia with minimized next-day residual sedation	Adds a functional treatment result
3	One or more tablets	Covers tablet administration
4	Each tablet contains about 3 mg	Directly maps to a 3 mg product
5	One or more capsules	Covers capsule administration
6	Difficulty during final 45 minutes	Narrower sleep-maintenance phenotype
7	Difficulty during final 30 minutes	Narrowest temporal sleep-maintenance limitation
8	About 1 mg doxepin	Low-dose embodiment
9	About 3 mg doxepin	Key commercial embodiment
10	About 6 mg doxepin	Key commercial embodiment
11	Doxepin hydrochloride	Covers the principal pharmaceutical salt
12	Patient aged 18 to under 65	Adult, non-geriatric population
13	Age 18 to under 65 and 3 mg or 6 mg	Main adult dose combination
14	Age 18 to under 65 and 3 mg	Adult 3 mg embodiment
15	Age 18 to under 65 and 6 mg	Adult 6 mg embodiment
16	Patient aged 65 or older	Geriatric population
17	Patient aged 65 or older and 3 mg	Geriatric 3 mg embodiment

What is the broadest enforceable commercial position?

Claim 1 is the principal commercial claim. It reaches oral doxepin products dosed from approximately 1 mg through approximately 7 mg when used for late-night sleep maintenance.

Claims 9 and 10 are particularly important because they cover approximately 3 mg and approximately 6 mg. Those strengths correspond to the FDA-approved Silenor tablets.[2]

Claims 14 and 15 narrow the adult population but provide more specific combinations that may be useful in litigation if claim 1 is challenged. Claim 17 is directed to the geriatric 3 mg regimen, which corresponds to the lower recommended starting dose for elderly patients.

What formulations are protected by United States Patent 10,653,662?

The patent protects use of an oral doxepin formulation, rather than a particular formulation composition.

Tablets

Claim 3 covers one or more tablets. Claim 4 specifies approximately 3 mg per tablet. Claims 9, 10, 14, 15, and 17 create additional 3 mg and 6 mg method combinations.

The patent therefore has strong relevance to immediate-release low-dose doxepin tablets used according to the Silenor label. It does not require a particular excipient, dissolution profile, coating, tablet hardness, release mechanism, or manufacturing process.

Capsules

Claim 5 covers one or more capsules. A capsule containing doxepin could fall within the claim if the administration method also satisfies the patient, dose, timing, and sleep-maintenance limitations.

Doxepin hydrochloride

Claim 11 expressly identifies doxepin hydrochloride. This limitation is commercially significant because Silenor is supplied as doxepin hydrochloride tablets.[2]

The claim set does not appear to depend on a proprietary salt form, particle size, polymorph, coating, or formulation technology. The primary protection is behavioral and clinical: who receives low-dose doxepin, at what dose, when, and for what sleep-maintenance problem.

Does the patent cover the FDA-approved Silenor regimen?

Yes, the claims substantially overlap the approved Silenor use.

Silenor is approved for the treatment of insomnia characterized by difficulty with sleep maintenance. The approved tablet strengths are 3 mg and 6 mg. The labeled adult dosing instruction is 6 mg once daily, with a 3 mg dose recommended for some patients, including elderly patients and patients sensitive to next-day effects.[2]

The overlap is strongest for:

3 mg or 6 mg doxepin hydrochloride tablets;
administration before bedtime;
adults with sleep-maintenance insomnia;
elderly patients receiving 3 mg;
use intended to reduce next-day residual sedation.

The patent claim range of about 1 mg to about 7 mg is broader than the two principal approved Silenor strengths. A product at 1 mg, 2 mg, 4 mg, 5 mg, or 7 mg could fall within claim 1 if the other limitations are met.

When does United States Patent 10,653,662 lose exclusivity?

The patent issued on May 19, 2020.[1] Its expiration date is governed by the earliest effective nonprovisional priority date and any applicable patent-term adjustment. The patent belongs to the earlier low-dose doxepin insomnia patent family, with an expected base expiration in March 2027 based on the family’s March 2006 priority date.

Event	Date or period
Earliest family priority	March 2006 family priority
Patent grant	May 19, 2020
Expected base patent expiry	March 2027
Statutory exclusivity after expiry	Patent claims cease to be enforceable, subject to any applicable adjustment

A continuation patent does not ordinarily receive a new 20-year term from its continuation filing date. Its term generally runs from the earliest effective nonprovisional filing date in the priority chain.[3]

The exact enforceable expiration should be determined from the USPTO patent-term calculation, including any patent-term adjustment. Patent expiration also does not eliminate separate FDA regulatory exclusivities or other unexpired patents.

Is United States Patent 10,653,662 an Orange Book patent?

Patent 10,653,662 is relevant to the Silenor NDA and the FDA’s method-of-use patent framework, but the patent number alone does not establish its current Orange Book listing status.

For an FDA-listed method-of-use patent, the Orange Book identifies the use code associated with the patent. The practical question is whether the listed use code covers the proposed generic label. An ANDA applicant can seek approval for a non-infringing label carve-out if the patented use can be omitted without making the remaining label misleading or incomplete.[4]

The regulatory significance depends on three items:

Whether the patent is listed against NDA 022036.
Whether the listed use code covers sleep-maintenance insomnia.
Whether the generic applicant makes a Paragraph IV certification or uses a section viii statement to carve out the patented method.

The FDA Orange Book does not decide infringement. It records listed patents and exclusivity information. Patent scope and infringement remain matters for the courts.

What Paragraph IV challenges and generic entry risks exist?

A generic doxepin applicant would have several possible regulatory strategies.

Paragraph IV certification

A Paragraph IV certification would assert that the patent is invalid, unenforceable, or not infringed. A filing that gives proper notice can trigger patent litigation under the Hatch-Waxman framework.[5]

The principal attack points would likely include:

Whether the claimed final-60-minute sleep-maintenance phenotype is adequately supported.
Whether the low-dose range and specific dose embodiments were obvious in view of earlier doxepin insomnia literature.
Whether the functional limitation concerning minimized next-day residual sedation is indefinite or insufficiently measurable.
Whether the accused product label directs the claimed use.
Whether the patent’s claims are properly supported by the priority disclosure.
Whether the claims are anticipated by prior clinical studies or earlier low-dose doxepin patents.

Section viii statement

A generic applicant may attempt to omit the patented sleep-maintenance use from its label. That strategy is more viable if the remaining label can lawfully describe another use, such as insomnia generally, without implicitly directing the patented use.

The claim language creates a label-risk problem. A label that states only “insomnia characterized by difficulty with sleep maintenance” may closely track the patent. A label that omits the final portion of the sleep period, the low-dose range, or the specific patented patient population may reduce literal infringement exposure, but the effectiveness of a carve-out depends on the full label and product marketing.

Generic launch scenarios

Scenario	Commercial outcome
No challenge before expiry	Generic launch generally waits until patent and regulatory barriers expire
Paragraph IV with litigation	Launch depends on litigation outcome, settlement terms, or a negotiated date
Successful section viii carve-out	Generic may launch for non-patented uses
Invalidity or non-infringement judgment	Earlier launch becomes possible
At-risk launch	Generic launches before final resolution and assumes infringement damages and injunction risk

Because claims 9 and 10 directly cover the 3 mg and 6 mg strengths, a generic product with the same strengths faces greater method-of-use exposure if its label retains the sleep-maintenance indication.

What is the patent strength of the claim set?

The patent has meaningful commercial relevance but a narrower litigation profile than a composition or formulation patent.

Strengths

The independent claim is tied to the FDA-recognized sleep-maintenance indication.
The 3 mg and 6 mg doses map directly to commercial Silenor strengths.
The claim covers both tablets and capsules through dependent claims.
The temporal sleep-maintenance limitation may distinguish ordinary claims to treating insomnia.
Claims separately cover adult and elderly populations.
Claim 11 expressly covers doxepin hydrochloride.

Weaknesses

The patent does not claim the active ingredient itself.
It does not claim a new chemical entity.
It does not require a distinctive formulation technology.
The final-60-minute limitation may create claim-construction and proof issues.
“About” dose language creates boundary questions around 1 mg and 7 mg.
The residual-sedation limitation in claim 2 may require clinical proof and may be vulnerable to indefiniteness or written-description arguments depending on the specification.
Direct infringement requires administration to a patient under the claimed conditions.

The highest-value claims are claims 1, 9, 10, 11, 14, 15, and 17. Claims 6 and 7 are narrower and may be harder to prove clinically because the claimant must establish difficulty staying asleep during the final 45 or 30 minutes.

How does this patent compare with composition and formulation patents?

Patent type	What it protects	Relevance to low-dose doxepin
Active-ingredient patent	Doxepin molecule or salt	Generally unavailable for an old active ingredient
Composition patent	Tablet, capsule, excipient, or release profile	Can block manufacture or sale of a formulation
Method-of-use patent	Treatment of a defined patient population	Main protection in Patent 10,653,662
Manufacturing patent	Process, purification, crystallization, or scale-up	Can create supply-chain barriers
Regulatory exclusivity	FDA approval-based protection	Separate from patent enforceability

Patent 10,653,662 does not create a manufacturing monopoly over doxepin. A competitor could potentially manufacture a chemically and physically different doxepin product while avoiding other formulation patents. The competitor would still face risk if its label or marketing directs the patented insomnia use.

What geographic coverage does the patent provide?

United States Patent 10,653,662 provides protection only in the United States. Corresponding foreign applications or grants may exist in the same family, but a U.S. patent does not block sales in Canada, Europe, Japan, or other jurisdictions.

For international freedom-to-operate analysis, the relevant questions are:

Whether the priority family was pursued in each jurisdiction.
Whether foreign claims retained the final-60-minute limitation.
Whether the foreign patents remain in force.
Whether local regulatory labeling creates method-of-use exposure.
Whether national patent-term adjustments or supplementary protection rights apply.

The U.S. patent is therefore a domestic method-of-use barrier, not a global doxepin exclusivity right.

Which companies are most exposed to this patent?

The direct commercial exposure is concentrated among:

The NDA holder and authorized Silenor marketers.
ANDA applicants seeking approval for 3 mg or 6 mg doxepin tablets.
Manufacturers supplying low-dose doxepin hydrochloride products.
Telehealth, pharmacy, and digital-prescribing businesses that promote low-dose doxepin for sleep maintenance.
Companies developing alternative oral doxepin products in the 1-to-7 mg range.

The risk is lower for:

Higher-dose doxepin products outside the claimed range.
Products labeled only for non-insomnia indications.
Products with a valid use carve-out.
Products marketed without directions corresponding to the claimed sleep-maintenance phenotype.

What litigation and settlement issues matter?

A Paragraph IV dispute would likely focus on both patent validity and label-based infringement. The claimant would need to show that the proposed generic’s intended use meets the claimed method. The applicant would likely argue that the label does not require treatment of difficulty during the final 60 minutes, that the claim is invalid over prior art, or that the relevant limitations are not adequately proven.

A settlement could provide:

A delayed generic entry date.
A license to the patent.
A label carve-out.
Restrictions on promotional language.
Authorized-generic supply terms.
No admission of infringement or validity.

The existence of a settlement would not itself establish patent validity. Its commercial effect would depend on the entry date, scope of the license, and whether the agreement was subject to FTC or DOJ review under the Medicare Prescription Drug, Improvement, and Modernization Act.[6]

Key Takeaways

Patent 10,653,662 is a low-dose doxepin method-of-use patent.
Claim 1 requires oral doxepin at approximately 1-7 mg, before bedtime, for difficulty staying asleep during the final 60 minutes of an intended eight-hour sleep period.
The 3 mg and 6 mg claims align closely with the approved Silenor strengths.
The patent covers treatment use, not doxepin manufacture, composition, or the active ingredient generally.
Claims 14, 15, and 17 provide targeted adult and elderly dose protections.
The expected family expiration is in March 2027, subject to the USPTO’s final patent-term calculation.
Generic risk depends heavily on Orange Book listing, use-code language, label design, Paragraph IV strategy, and any section viii carve-out.
A generic with a 3 mg or 6 mg label for sleep-maintenance insomnia faces the highest exposure.
There is no biosimilar pathway because doxepin is a small-molecule drug. The relevant pathway is an ANDA under Hatch-Waxman.
The patent is commercially meaningful but structurally narrower than a composition or formulation patent.

FAQs About United States Patent 10,653,662

Can a generic sell doxepin before Patent 10,653,662 expires?

It may be able to launch before expiry after a successful Paragraph IV challenge, a settlement license, a non-infringement determination, or an effective label carve-out.

Does Patent 10,653,662 cover 10 mg doxepin?

No. The independent claim is limited to about 1 mg through about 7 mg. A 10 mg dose is outside that numerical range, although other patents or regulatory restrictions could remain relevant.

Does the patent cover doxepin for depression?

The claims are directed to insomnia or a sleep disorder involving late-period difficulty staying asleep. They do not broadly claim doxepin treatment for depression.

Is a capsule containing 3 mg doxepin covered?

Potentially. Claim 5 covers capsules, while claims 1, 9, and 11 supply the dose and salt limitations. The patient, timing, and sleep-maintenance requirements must also be satisfied.

Can a company avoid the patent by changing the tablet excipients?

Not necessarily. The claims do not require a particular excipient system. A formulation change alone would not avoid a method claim if the product is still used according to the claimed method.

References

United States Patent and Trademark Office. (2020). United States Patent No. 10,653,662, Methods of treating insomnia.
U.S. Food and Drug Administration. (2020). Silenor (doxepin) tablets prescribing information. NDA 022036.
United States Patent and Trademark Office. (2024). Patent term adjustment and patent term calculation guidance.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book.
U.S. Congress. (1984). Drug Price Competition and Patent Term Restoration Act, Pub. L. No. 98-417, 98 Stat. 1585.
U.S. Congress. (2003). Medicare Prescription Drug, Improvement, and Modernization Act, Pub. L. No. 108-173, 117 Stat. 2066.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-001	Mar 17, 2010	AB	RX	Yes	No	⤷ Start Trial	⤷ Start Trial				TREATMENT OF INSOMNIA	⤷ Start Trial
Currax	SILENOR	doxepin hydrochloride	TABLET;ORAL	022036-002	Mar 17, 2010	AB	RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial				TREATMENT OF INSOMNIA	⤷ 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
Canada	2687118	⤷ Start Trial
Canada	2687124	⤷ Start Trial
European Patent Office	2026792	⤷ Start Trial
Japan	2009537553	⤷ Start Trial
Japan	2009537554	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,653,662

Which drugs does patent 10,653,662 protect, and when does it expire?

Summary for Patent: 10,653,662