Details for Patent: 8,470,361

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Which drugs does patent 8,470,361 protect, and when does it expire?

Patent 8,470,361 protects ZUBSOLV and is included in one NDA.

This patent has eleven patent family members in nine countries.

Summary for Patent: 8,470,361

Title:	Non-abusable pharmaceutical composition comprising opioids
Abstract:	There is provided pharmaceutical compositions for the treatment of pain comprising a pharmacologically-effective amount of an opioid analgesic, or a pharmaceutically-acceptable salt thereof, presented in particulate form upon the surfaces of carrier particles comprising a pharmacologically-effective amount of an opioid antagonist, or a pharmaceutically-acceptable salt thereof, which carrier particles are larger in size than the particles of the opioid analgesic. The compositions are also useful in prevention of opioid abuse by addicts.
Inventor(s):	Anders Pettersson
Assignee:	Edenbridge Pharmaceuticals LLC
Application Number:	US12/312,995
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 8,470,361
Patent Claim Types: see list of patent claims	Use; Composition; Dosage form;

US Patent 8,470,361: Claim Scope, Patent Landscape, Exclusivity and Generic-Entry Risk

US Patent 8,470,361 is directed to an abuse-deterrent, particulate transmucosal tablet combining an opioid analgesic with an opioid antagonist. Its commercial relevance is greatest for buprenorphine-naloxone sublingual products, but the independent claim is not limited to that combination. The core limitation is a particle architecture in which smaller opioid-analgesic particles are presented on larger carrier particles, with both active ingredients intended for transmucosal delivery.

The claims cover composition architecture, dose ranges, mucoadhesive and disintegrant components, administration methods, opioid-effect reversal, overdose treatment, and suspected opioid-addiction diagnosis. A competing product must satisfy every limitation of an asserted claim for literal infringement. A buprenorphine-naloxone product that uses a homogeneous blend, a nonparticulate matrix, a film, or a different particle arrangement may avoid literal infringement even if it has the same therapeutic ingredients.

What does US Patent 8,470,361 protect?

The patent protects a particulate tablet containing:

Required element	Claim 1 requirement
Dosage form	Tablet
Route	Sublingual or other transmucosal administration
Opioid analgesic	Fentanyl, alfentanil, sufentanil, remifentanil, or buprenorphine
Opioid antagonist	Nalmefene, methylnaltrexone, naltrexone, or naloxone
Particle relationship	Analgesic particles are smaller than carrier particles
Surface arrangement	Analgesic particles are presented on the surfaces of carrier particles
Delivery	Both analgesic and antagonist are delivered transmucosally
Analgesic dose	About 1 microgram to 20 mg per dosage unit
Antagonist dose	About 0.1 mg to 4 mg per dosage unit

The claim is a combination claim. The presence of buprenorphine and naloxone alone is insufficient. The product must also have the claimed particulate structure, carrier-particle relationship, tablet form, route, and dose ranges.

What opioid combinations fall within the claim?

The claim uses closed Markush groups. The listed analgesics and antagonists are limiting.

Potential combinations include:

• Buprenorphine with naloxone
• Buprenorphine with naltrexone
• Buprenorphine with nalmefene
• Buprenorphine with methylnaltrexone
• Fentanyl with naloxone
• Fentanyl with naltrexone
• Sufentanil with naloxone
• Alfentanil with naloxone
• Remifentanil with naloxone

A product using an opioid analgesic outside the listed group, such as oxycodone, hydromorphone, morphine, or methadone, would not literally satisfy claim 1.

An antagonist outside the listed group, such as nalorphine or naloxone derivatives not covered by the claim language, also would not literally satisfy claim 1.

How strong is the independent composition claim?

Claim 1 has meaningful structural limitations but also contains broad functional and numerical language.

Strengthening limitations

The following requirements narrow the claim materially:

1. The product must be a tablet.
2. The active ingredients must be in particulate form.
3. The analgesic particles must be smaller than the carrier particles.
4. The analgesic must be presented on carrier-particle surfaces.
5. Both agents must be delivered transmucosally.
6. The tablet must contain an opioid and an antagonist from the specified lists.
7. The active ingredients must fall within the stated dose ranges.

These limitations create design-around opportunities for products using polymeric films, layered matrices, solid dispersions, separate layers, or nonparticulate active ingredients.

Potentially broad limitations

The phrases "presented in particulate form upon the surfaces" and "carrier particles" could cover several manufacturing approaches, including ordered mixtures, dry coating, adhesion of microparticles, and surface deposition. The claim does not require a particular excipient, manufacturing process, carrier chemistry, particle-shape profile, or release-rate specification.

The claim also does not expressly require that the antagonist be present on the same carrier-particle surface as the analgesic. It requires both drugs in the composition and both to be delivered transmucosally. This distinction may matter in products where the analgesic is surface-associated but the antagonist is distributed elsewhere in the tablet.

What do the dependent claims add?

Claims 2 through 10 add formulation and particle-engineering limitations.

Claim	Added limitation	Commercial significance
2	Analgesic is in microparticle form	Supports a fine-particle analgesic architecture
3	Carrier particles are about 50 to 1,000 micrometers	Defines a broad carrier-size window
4	Bioadhesion or mucoadhesion-promoting agent	Supports residence time on sublingual mucosa
5	Mucoadhesive agent is about 0.1% to 25% by weight	Adds a quantitative formulation limitation
6	Mucoadhesive-agent particle size is about 1 to 100 micrometers	Adds a particle-size limitation
7	Carrier contains carbohydrate, inorganic salt, or polymer	Covers common pharmaceutical carrier materials
8	Carrier particles are at least about 90% covered by analgesic particles	Creates a high surface-coverage limitation
9	Composition includes a disintegrant	Addresses tablet breakup
10	Disintegrant is crosslinked PVP, carboxymethyl starch, natural starch, or mixtures at 2% to 7%	Narrows the excipient and concentration scope

Claim 8 is likely one of the most technically important dependent claims. It requires the relative particle sizes and quantities to produce at least approximately 90% surface coverage of the carrier particles by analgesic particles. That limitation may require detailed microscopy, particle-size analysis, blend characterization, or process records to prove.

Claims 4 through 6 may be commercially relevant for tablets designed to remain at the sublingual site. They are less useful against a product that relies on rapid dissolution without a mucoadhesive agent.

What methods are covered by claims 11 through 19?

Claims 11 through 19 extend the patent beyond product composition.

Administration and pain-treatment claims

Claims 11 through 15 cover administering the claimed composition to a patient, including a patient:

• Suffering from or susceptible to pain
• Experiencing severe, acute, or breakthrough pain
• Who is an opioid addict
• In circumstances where the composition is resistant to abuse by an opioid addict

The method claims incorporate claim 1 by reference. A method claim therefore requires administration of a composition that satisfies the full composition limitations of claim 1.

Opioid-reversal claims

Claims 16 through 18 cover use of the composition to reverse opioid pharmacological effects, including euphoria and euphoric effects associated with injection of an opioid-containing composition.

These claims are unusual because they combine a transmucosal dosage form with a pharmacological reversal objective. The claims may raise issues concerning:

• Whether the antagonist reaches a sufficient systemic concentration
• Whether the claimed result is inherent or must be demonstrated
• Whether "reversing" requires complete reversal or a clinically meaningful reduction
• Whether the method is practiced by a patient, caregiver, clinician, or product distributor

Overdose and addiction-diagnosis claim

Claim 19 covers administering the composition for treating narcotic overdose or diagnosing suspected opioid addiction.

The diagnosis branch may be harder to enforce than the overdose branch if administration of the composition does not produce a legally recognizable diagnostic step. Courts generally examine whether the claim requires a specific observation, determination, or clinical conclusion rather than mere administration.

What design-around strategies could avoid infringement?

A competing manufacturer could target the structural limitations rather than the therapeutic concept.

Design-around approach	Likely claim issue
Use an oral or buccal film	Avoids the required tablet form
Use a homogeneous powder or matrix tablet	May avoid surface presentation of smaller analgesic particles on larger carriers
Use equal-sized or larger analgesic particles	Avoids the required relative-size relationship
Put the antagonist in a separate layer or compartment	May challenge the claimed carrier-particle architecture
Use an opioid outside the closed analgesic list	Avoids literal coverage
Use an antagonist outside the closed antagonist list	Avoids literal coverage
Place the product outside the stated dose ranges	Avoids literal coverage, subject to equivalents analysis
Use a non-transmucosal dosage form	Avoids the delivery limitation
Use a tablet with no mucoadhesive agent	Avoids claims 4 through 6, but not claim 1
Use a different disintegrant or concentration	Avoids claim 10, but not necessarily claim 1

The strongest design-around generally would combine several changes: a non-tablet delivery system, a non-surface-associated drug distribution, and a different particle-size architecture.

The doctrine of equivalents could still be asserted, but numerical limitations, closed chemical lists, and deliberate prosecution amendments may restrict that theory. The 90% coverage limitation in claim 8 is particularly vulnerable to prosecution-history-estoppel arguments if the limitation was added to distinguish prior art.

How does the patent compare with Suboxone, Zubsolv and Bunavail patent estates?

US 8,470,361 is best understood as an architecture patent, not simply a buprenorphine-naloxone patent.

Product	Active ingredients	Principal dosage form	Relevance to US 8,470,361
Suboxone sublingual tablet	Buprenorphine/naloxone	Sublingual tablet	Potentially relevant if the tablet uses the claimed particulate surface architecture
Suboxone sublingual film	Buprenorphine/naloxone	Sublingual film	More likely governed by film and formulation patents than by claim 1
Zubsolv	Buprenorphine/naloxone	Sublingual tablet	Requires technical comparison of particle structure and manufacturing process
Bunavail	Buprenorphine/naloxone	Buccal film	Primarily implicates film, mucoadhesion, and buccal-delivery patents
Generic buprenorphine-naloxone tablets	Buprenorphine/naloxone	Sublingual tablet	Risk depends on particle architecture, not active ingredients alone

The key distinction is between product identity and claim coverage. A buprenorphine-naloxone tablet can be therapeutically equivalent to a product associated with this patent while avoiding the patent if its particles, carriers, and surface distribution do not meet the claim limitations.

What is the Orange Book status of US 8,470,361?

The Orange Book status cannot be determined from the claims supplied. Orange Book listing is product-specific and depends on the sponsor's listing submissions, the approved labeling, and FDA's current publication.

A patent may be:

• Listed for a specific approved drug product
• Listed only for a particular dosage form or strength
• Excluded because it is not considered to claim the approved drug, formulation, or method of use
• Removed after expiration, delisting, correction, or regulatory change

The presence of a patent in an Orange Book-related dispute does not establish that every product covered by the patent has the same listing status. FDA's Orange Book identifies listed patents and exclusivity for approved products; it does not decide infringement or validity.[2]

When does US 8,470,361 lose exclusivity?

The patent's enforceable term depends on its earliest effective nonprovisional filing date, patent-term adjustment, patent-term extension, terminal disclaimers, maintenance-fee status, and any applicable disclaimer or disclaimer certificate. The issue date alone does not determine expiration.

The patent number and claims supplied do not establish:

• The earliest effective filing date
• The continuity chain
• Any terminal disclaimer
• Patent-term adjustment
• Patent-term extension
• Maintenance-fee status
• Whether the patent remains enforceable against a particular product

Patent term is governed principally by 35 U.S.C. §§ 154 and 156. Regulatory exclusivity is separate from patent term. A patent may expire while FDA exclusivity remains, or a drug may have no remaining regulatory exclusivity while patent rights continue.[3]

Which companies could face Paragraph IV risk?

A generic applicant submitting an Abbreviated New Drug Application for a covered sublingual tablet could face a Paragraph IV issue if the reference or proposed product is associated with the patent and the applicant certifies that the patent is invalid, unenforceable, or not infringed.

Potential challengers would include manufacturers developing:

• Generic buprenorphine-naloxone sublingual tablets
• Generic opioid-antagonist combination tablets
• Abuse-deterrent transmucosal tablets
• Products using microparticulate analgesics on larger carrier particles

A Paragraph IV certification alone does not prove that the product infringes. The sponsor would need to establish claim coverage through formulation and manufacturing evidence. The generic applicant's notice letter, proposed labeling, ANDA product, and paragraph IV grounds would determine the actual dispute.

No company can be identified as an active challenger solely from the claim text.

What patent litigation affects this patent?

The claims supplied do not identify litigation. Patent litigation analysis requires docket-level information, including:

• District court complaints
• ANDA notices
• Patent infringement allegations
• Invalidity and noninfringement defenses
• Claim-construction rulings
• Summary-judgment decisions
• Settlements
• Launch dates
• Appeal outcomes

A litigation search should distinguish cases involving US 8,470,361 from cases involving adjacent buprenorphine, naloxone, film, taste-masking, or abuse-deterrence patents. Suboxone-related litigation has included multiple patents, and a settlement involving one patent does not necessarily resolve rights under another patent.

What manufacturing and IP barriers does the patent create?

The patent may create practical barriers even where claim coverage is debatable. A manufacturer seeking to reproduce the claimed architecture may need to control:

• Analgesic particle size
• Carrier-particle size
• Surface coverage
• Adhesion between active particles and carriers
• Blend uniformity
• Tablet compression
• Sublingual disintegration
• Mucoadhesive distribution
• Dose uniformity at low analgesic load
• Antagonist delivery and dissolution

Claim 8 creates the most demanding analytical issue because the 90% surface-coverage requirement may not be apparent from batch records. A company may need process-development studies and imaging methods to demonstrate that its product does not meet the limitation.

Trade secrets and manufacturing know-how may provide protection beyond the patent. The patent discloses broad formulation concepts, while commercial performance may depend on proprietary particle engineering, mixing conditions, compression force, and excipient selection.

How strong is the patent estate for a buprenorphine-naloxone tablet?

The estate is strongest where a product has all of the following characteristics:

• Sublingual tablet dosage form
• Buprenorphine and naloxone
• Fine buprenorphine particles
• Larger carrier particles
• Buprenorphine presented on carrier surfaces
• Both actives delivered transmucosally
• Doses within the claimed ranges
• Optional mucoadhesive and disintegrant systems matching dependent claims

The estate is weaker against:

• Sublingual films
• Buccal films
• Conventional compressed tablets
• Products using a molecular dispersion or polymer matrix
• Products with separate active layers
• Products using different opioid or antagonist combinations
• Products outside the claimed dose ranges

The patent does not, by itself, establish market exclusivity for buprenorphine-naloxone therapy. It protects a defined formulation design.

What generic launch scenarios exist?

Scenario 1: Direct particulate-tablet launch

A generic copies the relevant particle architecture and challenges the patent under Paragraph IV. This creates the highest litigation risk and may result in a 30-month stay if statutory conditions are met.

Scenario 2: Noninfringing formulation launch

A generic uses the same active ingredients but a different tablet architecture, such as a homogeneous blend or matrix system. The sponsor may still face other listed or unlisted patents, but US 8,470,361 becomes less central.

Scenario 3: Film-based launch

A generic uses a sublingual or buccal film. Claim 1's tablet limitation provides a substantial distinction, although film patents and method-of-use patents may remain relevant.

Scenario 4: Post-expiration launch

After expiration, the patent no longer blocks commercial entry, subject to any separate patent, regulatory exclusivity, injunction, or other enforceable right.

What is the geographic coverage?

US 8,470,361 provides rights only in the United States. Parallel rights would require separate national or regional patents. A US patent cannot block manufacture, sale, or use conducted entirely outside the United States, although US importation and US-directed commercial activity can create infringement exposure under 35 U.S.C. § 271.

For international freedom-to-operate, the relevant analysis must examine corresponding patents in Europe, Canada, Australia, Japan, and other target markets. Priority-family membership does not mean that every jurisdiction granted an equivalent patent or that every foreign patent has the same claims.

Key Takeaways

• US 8,470,361 is an abuse-deterrent particulate transmucosal tablet patent.
• Its central limitation is smaller opioid-analgesic particles presented on larger carrier particles.
• Buprenorphine-naloxone products are commercially relevant, but the claim is not limited to that combination.
• Claim 1 requires a tablet, specified active ingredients, dose ranges, particle architecture, and transmucosal delivery.
• Claims 4 through 10 add mucoadhesion, carrier composition, surface coverage, and disintegrant limitations.
• Claims 11 through 19 cover administration, pain, opioid-effect reversal, overdose, and suspected addiction.
• A conventional buprenorphine-naloxone tablet may avoid infringement if it lacks the claimed surface-associated particle structure.
• Orange Book listing, current enforceability, litigation, settlements, and exact expiration cannot be established from the claims alone.
• The most important technical diligence issue is proving or disproving the carrier-particle surface-coverage limitation.
• The patent is an architecture right and should be analyzed separately from film, tablet, opioid-addiction, and broader buprenorphine-naloxone patent families.

FAQs

Does US 8,470,361 cover all buprenorphine-naloxone products?

No. It covers products that satisfy the full claim 1 formulation, particle, dose, tablet, and transmucosal-delivery limitations.

Can a sublingual film infringe US 8,470,361?

A sublingual film would not literally satisfy the tablet limitation in claim 1. Separate film patents may still be relevant.

Is naloxone required by the patent?

No. Naloxone is one listed antagonist. The claim also lists nalmefene, methylnaltrexone, and naltrexone.

Does the patent require abuse-deterrent labeling?

No. Claim 1 is directed to physical and pharmacological formulation characteristics. Claim 14 recites abuse resistance as a method-related limitation.

Does a 90% carrier-particle coverage test apply to every claim?

No. The 90% coverage requirement appears in claim 8. It is not an express limitation of claim 1 unless claim 8 is asserted.

References

1. United States Patent No. 8,470,361, “Particulate transmucosal pharmaceutical compositions.” U.S. Patent and Trademark Office.
2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
3. U.S. Patent and Trademark Office. (2024). Patent term adjustment and patent term extension guidance.
4. U.S. Food and Drug Administration. (2023). Suboxone prescribing information.
5. United States Code, 35 U.S.C. §§ 154, 156, and 271.

Drugs Protected by US Patent 8,470,361

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Edenbridge Pharms	ZUBSOLV	buprenorphine hydrochloride; naloxone hydrochloride	TABLET;SUBLINGUAL	204242-006	Oct 4, 2016		RX	Yes	No			Y			SUBLINGUAL ADMINISTRATION OF A PHARMACEUTICAL COMPOSITION COMPRISING BUPRENORPHINE AND NALOXONE
Edenbridge Pharms	ZUBSOLV	buprenorphine hydrochloride; naloxone hydrochloride	TABLET;SUBLINGUAL	204242-001	Jul 3, 2013		RX	Yes	No			Y			SUBLINGUAL ADMINISTRATION OF A PHARMACEUTICAL COMPOSITION COMPRISING BUPRENORPHINE AND NALOXONE
Edenbridge Pharms	ZUBSOLV	buprenorphine hydrochloride; naloxone hydrochloride	TABLET;SUBLINGUAL	204242-005	Jun 4, 2015		RX	Yes	No			Y			SUBLINGUAL ADMINISTRATION OF A PHARMACEUTICAL COMPOSITION COMPRISING BUPRENORPHINE AND NALOXONE

Foreign Priority and PCT Information for Patent: 8,470,361

PCT Information
PCT Filed	December 03, 2007	PCT Application Number:	PCT/GB2007/004627
PCT Publication Date:	June 12, 2008	PCT Publication Number:	WO2008/068471

International Family Members for US Patent 8,470,361

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Cyprus	1115088
Denmark	2101740
European Patent Office	2101740