Details for Patent: 9,597,281

Which drugs does patent 9,597,281 protect, and when does it expire?

Patent 9,597,281 protects EDLUAR and is included in one NDA.

This patent has twenty patent family members in twelve countries.

Summary for Patent: 9,597,281

Title:	Pharmaceutical formulations useful in the treatment of insomnia
Abstract:	There is provided a formulation suitable for transmucosal administration comprising a short acting hypnotic drug, which formulation provides a measurable plasma concentration of drug within 10 minutes of administration. The formulation is capable of providing sleep on demand, and preferably comprises particles of drug, for example zolpidem or a pharmaceutically-acceptable salt thereof and a mucoadhesion promoting agent, such as sodium carboxymethylcellulose, which particles of drug and mucoadhesive are presented upon the surface of larger carrier particles.
Inventor(s):	Anders Pettersson, Christer Nystrom, Susanne Bredenberg
Assignee:	Orexo AB
Application Number:	US13/870,737
Patent Claim Types: see list of patent claims	Use; Composition; Formulation; Device; Dosage form;

US Patent 9,597,281: Scope, Claim Construction, Exclusivity and Zolpidem Patent Landscape

US Patent 9,597,281 protects a specific sublingual zolpidem tablet platform rather than zolpidem generally. The asserted combination is a small tablet containing micronized zolpidem or zolpidem salt, carrier particles, and a mucoadhesion-promoting agent, with particles distributed on the carrier-particle surfaces. The independent claims also require pharmacokinetic and clinical outcomes, including measurable zolpidem in plasma within 10 minutes and sleep maintenance for at least six hours.[1]

The patent has its greatest commercial relevance to sublingual zolpidem products in the 5 mg to 12 mg dose range, particularly formulations using mannitol, croscarmellose sodium, microcrystalline cellulose, magnesium stearate, and approximately 80 mg tablets.

What does US Patent 9,597,281 cover?

The patent covers a method of administering a defined sublingual zolpidem formulation to treat insomnia or provide sleep on demand. It does not claim every zolpidem tablet, every sublingual dosage form, or zolpidem as an active ingredient.

The core elements are:

Claim element	Required limitation
Active ingredient	Zolpidem or a pharmaceutically acceptable salt
Dose	About 5 mg to about 12 mg per tablet
Dosage form	Tablet sized for placement under the tongue
Carrier	Particles with exterior surfaces
Particle architecture	Smaller zolpidem particles presented at least partly on carrier surfaces
Mucoadhesion agent	Smaller particles also presented at least partly on carrier surfaces
Pharmacokinetics	Measurable plasma concentration within 10 minutes
Tmax relationship	80 to 160 minutes between first measurable concentration and maximum concentration
Sleep effect	Plasma concentration capable of maintaining sleep for at least six hours
Administration	Sublingual placement under the tongue

The claim is therefore a combination claim. A competing product must satisfy the formulation, particle-distribution, dosage, administration, and outcome limitations to fall within the literal scope of claim 1 or claim 3.

How do independent claims 1 and 3 differ?

Claims 1 and 3 protect substantially the same formulation and pharmacokinetic profile but use different treatment objectives.

Claim	Protected use
Claim 1	Treating insomnia
Claim 3	Providing sleep on demand

Claim 1 expressly covers insomnia treatment and supports the dependent limitation for transient insomnia in claim 2. Claim 3 uses the broader commercial concept of sleep on demand, but it still requires the same tablet composition, sublingual administration, and specified plasma and sleep outcomes.

The two independent claims create alternative infringement theories. A product may be relevant under either the insomnia-treatment language or the sleep-on-demand language, subject to proof of all formulation and outcome limitations.

What formulation architecture is protected?

The most important technical limitation is the distribution of zolpidem and mucoadhesion-promoting particles on the exterior surfaces of larger carrier particles.

Carrier-particle system

The carrier particles are larger than the zolpidem and mucoadhesion-agent particles. Claim 18 specifies a carrier-particle weight-based mean diameter of approximately 150 micrometers to 400 micrometers. Claims 19 and 20 narrow the carrier to mannitol, including spray-dried mannitol.

Claim 21 requires the carrier to comprise approximately 70% to 85% by weight of the composition.

Zolpidem particle system

Claim 8 specifies microparticles. Claim 9 narrows the zolpidem microparticles to a weight-based mean diameter of approximately 1 micrometer to 10 micrometers.

Claim 10 requires zolpidem or its salt to comprise approximately 5% to 15% by weight of the composition. Claim 7 specifically identifies zolpidem hemitartrate.

Surface coverage

Claim 22 requires zolpidem particles to cover at least 90% of the carrier-particle exterior surfaces. Claim 23 narrows coverage to approximately 130% to 180%.

The coverage language is potentially significant in litigation. It may require particle-imaging, surface-area, particle-distribution, or manufacturing-record evidence. A formulation containing the same excipients but produced through a different granulation, coating, spray-drying, or blending process may not necessarily satisfy the surface-coverage limitations.

Mucoadhesion-promoting agent

Claims 11 and 12 identify sodium carboxymethylcellulose and croscarmellose sodium, respectively. Claim 13 specifies approximately 3.5% to 6.5% by weight.

The mucoadhesion agent is not merely an excipient in the claim structure. Its particle size and presentation on the carrier surfaces are part of the claimed architecture.

Tablet composition

The dependent claims identify:

Component	Limitation
Binder or disintegrant	Required by claim 14
Microcrystalline cellulose	Claim 15
Silicified microcrystalline cellulose	Claim 16
Binder loading	Approximately 2.0% to 3.0% by weight
Lubricant	Claim 24
Magnesium stearate	Claim 25
Tablet dimensions	Approximately 80 mg and 6 mm diameter

These limitations create narrower fallback positions. A product may avoid claims 15, 16, 25, or 26 while still raising risk under broader claims 1, 3, 4, 8, 11, 18, 19, or 21.

What pharmacokinetic outcomes are required?

Claims 1 and 3 contain three outcome limitations:

1. A measurable plasma concentration within 10 minutes.
2. A period of approximately 80 to 160 minutes between the first measurable concentration and maximum measured concentration.
3. A plasma concentration capable of maintaining sleep for at least six hours.

Claim 6 adds a fourth outcome: no decreased alertness or psychomotor impairment after at least seven hours of sleep.

These limitations may narrow literal infringement, but they create complex proof issues. The patent does not simply require a dissolution profile or a particular Cmax and Tmax. It requires a measured or functional clinical outcome tied to sublingual administration.

The phrase "capable of maintaining sleep" is functional and may require clinical, pharmacokinetic-pharmacodynamic, or product-label evidence. The phrase "measurable plasma concentration" raises analytical-method questions, including assay sensitivity, sampling intervals, lower limits of quantification, and treatment of a concentration measured at the first post-dose time point.

What dissolution characteristics are protected?

Claims 4 and 5 require rapid zolpidem release:

Claim	Dissolution requirement
Claim 4	At least 50% released within five minutes
Claim 5	At least 50% released within three minutes

The test is specified as a standard in vitro paddle apparatus using USP phosphate buffer at pH 6.8.

These claims are narrower than the independent claims because they require a particular dissolution result in addition to the formulation and pharmacokinetic limitations. A generic or competing product may challenge the claims by demonstrating that its formulation does not meet the three-minute or five-minute release threshold, although dissolution alone would not resolve the broader method claims.

How strong is the patent estate based on the claim structure?

The patent has moderate structural strength and potentially weaker enforcement predictability because the independent claims combine detailed composition limitations with outcome requirements.

Strength factor	Assessment
Specific particle architecture	Stronger protection against closely copied formulations
Defined excipient system	Supports product fingerprinting
Narrow dose range	Limits coverage to approximately 5-12 mg
Pharmacokinetic limitations	May distinguish conventional oral zolpidem
Clinical sleep-maintenance limitation	Raises proof burden
Functional "capable of" language	Potentially broad but fact-intensive
Surface-coverage limits	Technically difficult to assess
Method-of-treatment format	Requires proof of administration or induced infringement
Dependent dissolution claims	Useful fallback claims if testing is reproducible

The strongest practical position is likely against a product that copies the same excipient classes, particle sizes, tablet dimensions, and sublingual performance profile. The weakest position is against a conventional sublingual tablet using a different particle architecture and lacking the claimed plasma or sleep-maintenance profile.

When does US Patent 9,597,281 lose exclusivity?

Patent expiration cannot be determined from the claim text alone. The controlling date is generally 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers, patent-term extension, and any applicable continuity relationship.[2]

The issue date does not establish the expiration date. A continuation patent may share an earlier priority date with a parent application, and a terminal disclaimer may limit the term to another patent. The live status must be confirmed through the USPTO Patent Center and the patent’s continuity, maintenance-fee, terminal-disclaimer, and patent-term records.[3]

The patent’s enforceability also depends on maintenance-fee payment. Failure to pay a required fee can result in expiration for nonpayment, subject to statutory reinstatement procedures.

What is the Orange Book status of US Patent 9,597,281?

A patent is Orange Book-relevant only if it is listed by the NDA holder for an approved drug and falls within the FDA’s listing categories for drug substance, drug product, or approved method of use.[4]

The claim text suggests a drug-product and method-of-use relationship, but the claims alone do not establish that Patent 9,597,281 is listed for a particular zolpidem NDA. Orange Book relevance must be analyzed against the approved product, NDA holder, listed patent number, use code, and current listing status.

For sublingual zolpidem, the principal FDA-approved products historically include:

Product	Active ingredient	Dosage form	Commercial relevance
Edluar	Zolpidem tartrate	Sublingual tablet	5 mg and 10 mg strengths
Intermezzo	Zolpidem tartrate	Sublingual tablet	Low-dose middle-of-the-night treatment
Ambien and generic equivalents	Zolpidem tartrate	Immediate-release oral tablet	Not inherently within the sublingual claims

An ordinary oral zolpidem tablet would not meet the administration limitation. An approved sublingual product may still avoid the patent if its composition, particle distribution, dose, dissolution, or pharmacokinetic profile differs.

Which companies and products are most relevant?

Edluar and related sublingual zolpidem products

Edluar is the closest commercial comparator because it is a sublingual zolpidem tablet in 5 mg and 10 mg strengths. The overlap is strongest at the dosage-form and active-ingredient level. Patent risk depends on whether the marketed formulation uses the claimed carrier-particle architecture and whether it produces the claimed pharmacokinetic outcomes.

Intermezzo

Intermezzo is a sublingual zolpidem product but is directed to middle-of-the-night awakening and uses lower strengths than the approximately 5 mg to 12 mg range recited in claims 1 and 3. Its lower dose and different indication reduce literal overlap with the independent claims, although other patent families may be relevant.

Conventional generic zolpidem

Generic immediate-release oral zolpidem tablets generally do not satisfy the sublingual-administration requirement. A generic manufacturer developing a sublingual version would face substantially greater risk because it would need to address the tablet, particle, dissolution, pharmacokinetic, and clinical limitations together.

What Paragraph IV challenges and litigation risks exist?

A Paragraph IV certification would be relevant if an ANDA applicant seeks approval for a product referencing an NDA with a listed patent. The applicant would need to assert that the patent is invalid, unenforceable, or not infringed under the Hatch-Waxman framework.[5]

Potential invalidity and noninfringement positions include:

1. The accused tablet does not use carrier particles with zolpidem and mucoadhesion-agent particles presented on their exterior surfaces.
2. The zolpidem particle size falls outside the approximately 1-10 micrometer range.
3. The carrier is not mannitol or does not have the claimed size distribution.
4. The zolpidem dose is outside the 5-12 mg range.
5. The formulation does not release at least 50% within three or five minutes.
6. The product does not produce the claimed 10-minute plasma, 80-160-minute Tmax interval, or six-hour sleep outcome.
7. The claims are indefinite because terms such as "measurable," "capable of maintaining sleep," or surface "coverage" lack reproducible boundaries.
8. The claimed combination was obvious over prior sublingual zolpidem formulations, fast-dissolving tablets, micronized-drug carrier systems, and mucoadhesive excipient technology.[6]

The method claims also create a divided-infringement issue. Direct infringement requires administration of the product to a patient. A manufacturer may face induced-infringement exposure if its labeling or promotional materials direct the claimed sublingual use, but product composition alone does not automatically establish direct infringement of a treatment method.

What geographic coverage does the patent provide?

US Patent 9,597,281 provides US rights only. It does not block manufacture, sale, or use outside the United States. International risk must be evaluated through corresponding applications and national-phase patents in Europe, Canada, Australia, Japan, and other relevant markets.

The existence of a US patent does not establish that corresponding foreign patents were granted, remain in force, or have identical claims. Patent families frequently diverge during prosecution.

What manufacturing and IP barriers matter most?

The most difficult design-around issues are likely to involve:

• Achieving rapid sublingual dissolution without placing micronized zolpidem on carrier surfaces.
• Replacing mannitol with another carrier.
• Using a different mucoadhesive or disintegrant.
• Altering particle-size distributions.
• Producing a dose below 5 mg or above 12 mg where clinically acceptable.
• Using a tablet with a different weight or geometry.
• Delivering zolpidem through an oral film, spray, lozenge, capsule, or buccal system rather than the claimed tablet.
• Designing a pharmacokinetic profile outside the claimed time ranges.

A formulation design-around must be assessed against the broad independent claims first. Avoiding magnesium stearate or silicified microcrystalline cellulose would avoid only narrower dependent claims and may not eliminate the principal risk.

How does US Patent 9,597,281 compare with conventional zolpidem patents?

Patent category	Typical protection	Relationship to US 9,597,281
Zolpidem compound patents	Active pharmaceutical ingredient	Generally expired or historically foundational
Immediate-release oral tablets	Conventional oral formulations	Usually outside the sublingual method claims
Sublingual zolpidem patents	Sublingual delivery and rapid onset	Directly relevant
Low-dose middle-of-night products	Intermezzo-type use and strengths	Partly differentiated by dose and indication
Particle-engineering patents	Microparticles, carrier surfaces, dissolution	Technically relevant to the asserted architecture
Method-of-use patents	Insomnia, transient insomnia, sleep maintenance	Relevant where the product label directs the claimed use

What revenue exposure and generic-launch scenarios are most likely?

The patent’s commercial value depends on whether it covers the approved product actually sold by the patent owner or NDA holder. If the patent is listed against a currently marketed sublingual zolpidem product, a Paragraph IV challenge could trigger a 30-month stay under applicable Hatch-Waxman procedures, subject to statutory exceptions and litigation outcomes.[5]

Potential launch scenarios are:

Scenario	Commercial effect
Close formulation copy	High infringement risk and likely litigation
Conventional oral generic	Limited relevance to the patent
Sublingual design-around	Development cost and clinical bridging risk
Alternative oral film or spray	Lower literal risk, separate regulatory pathway
Patent invalidated	Earlier competitive entry
Patent not listed or not enforceable	Reduced Hatch-Waxman delay risk
Settlement with license	Controlled entry date, royalties, or supply restrictions

Revenue exposure is highest where the protected formulation is the only approved sublingual product in a defined insomnia indication. It is lower where patients can readily substitute conventional oral zolpidem or other hypnotics.

Key Takeaways

• US Patent 9,597,281 claims a sublingual zolpidem treatment method tied to a defined particle-on-carrier formulation.
• Claims 1 and 3 are the principal claims and differ mainly in the treatment objective.
• The most important technical limitations are micronized zolpidem, carrier-surface presentation, a mucoadhesion-promoting agent, rapid plasma appearance, and six-hour sleep maintenance.
• Claims 4 and 5 add rapid dissolution thresholds of at least 50% release within five or three minutes.
• Claims 7-26 create narrower positions covering hemitartrate, croscarmellose sodium, silicified microcrystalline cellulose, mannitol, magnesium stearate, particle sizes, surface coverage, and tablet dimensions.
• Conventional oral zolpidem products generally fall outside the sublingual method claims.
• Edluar is the closest commercial comparator; Intermezzo is differentiated by its lower-dose, middle-of-the-night use.
• Exact patent expiration, Orange Book listing, terminal-disclaimer effect, maintenance status, and litigation exposure require the current USPTO and FDA records.
• A credible design-around would normally change the particle architecture, carrier system, dosage form, or pharmacokinetic profile rather than only removing a narrow excipient limitation.

FAQs

Does US Patent 9,597,281 cover a 10 mg oral zolpidem tablet?

No. The independent claims require sublingual administration of a tablet placed under the tongue. A conventional swallowed 10 mg zolpidem tablet does not satisfy that limitation.

Does using zolpidem tartrate avoid the patent?

Not necessarily. Claim 7 expressly covers zolpidem hemitartrate, and the independent claims broadly cover zolpidem and pharmaceutically acceptable salts.

Can a competitor avoid the patent by replacing mannitol?

Potentially, but replacing mannitol addresses only the narrower mannitol-dependent claims. The broader claims do not expressly require mannitol, so the remaining particle, mucoadhesion, dose, administration, and outcome limitations must also be evaluated.

Are sublingual films covered by the patent?

The cited claims require a tablet sized for placement under the tongue. A film is not automatically within those claims, although separate patents or product-specific infringement theories may apply.

Does rapid dissolution alone establish infringement?

No. Rapid dissolution is required only by dependent claims 4 and 5. The independent claims also require the specified formulation architecture, dose, sublingual administration, pharmacokinetic profile, and sleep-maintenance outcome.

References

1. U.S. Patent No. 9,597,281, claims 1-26 (U.S. Patent and Trademark Office, 2017).
2. 35 U.S.C. § 154.
3. U.S. Patent and Trademark Office. (n.d.). Patent Center and patent term adjustment information.
4. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book.
5. 21 U.S.C. § 355(j).
6. 35 U.S.C. §§ 102, 103, 112.

Drugs Protected by US Patent 9,597,281

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Viatris	EDLUAR	zolpidem tartrate	TABLET;SUBLINGUAL	021997-001	Mar 13, 2009	AB	RX	Yes	No	9,597,281					METHOD OF TREATING INSOMNIA CHARACTERIZED BY DIFFICULTY WITH SLEEP ONSET
Viatris	EDLUAR	zolpidem tartrate	TABLET;SUBLINGUAL	021997-002	Mar 13, 2009	AB	RX	Yes	Yes	9,597,281					METHOD OF TREATING INSOMNIA CHARACTERIZED BY DIFFICULTY WITH SLEEP ONSET

Foreign Priority and PCT Information for Patent: 9,597,281

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	0423800.2	Oct 27, 2004

International Family Members for US Patent 9,597,281

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Cyprus	1118414
Cyprus	1119580
Denmark	1807156
Denmark	2340872
European Patent Office	1807156
European Patent Office	2340872
Spain	2610469