United States Drug Patent 8,075,872: Scope, Claims, Expiration, and Patent Landscape

U.S. Patent No. 8,075,872 protects abuse-deterrent opioid dosage forms made by hot extrusion using high-molecular-weight polyalkylene oxide, principally polyethylene oxide, as a controlled-release matrix. The patent also covers manufacturing processes using extrusion pressure of at least 10 bar, temperatures below 180°C, inert-gas processing, and conversion of extrudate into tablets or other non-multiparticulate forms.

The patent issued on December 13, 2011, from an application claiming priority to August 27, 2003. Its 20-year patent term ran from the international/nonprovisional filing date and reached its ordinary expiration in August 2024, subject to any recorded patent-term adjustment. It therefore does not provide current U.S. exclusionary rights unless a specific term adjustment or other surviving right applies. The patent is directed to small-molecule opioid products, not biologics, and biosimilar law is not relevant.

What does U.S. Patent 8,075,872 protect?

The patent protects a combination of formulation architecture and manufacturing conditions.

Claim group	Subject matter	Commercial significance
Claims 1-18	Abuse-deterrent opioid dosage forms	Covers product composition, matrix, physical strength, extrusion, and optional aversive features
Claims 2-5	Tablet, polyalkylene oxide, and wax limitations	Narrows the dosage form and matrix materials
Claims 6-17	Irritants, viscosity agents, antagonists, emetics, dyes, and bittering agents	Covers chemical and sensory abuse-deterrence mechanisms
Claim 18	Spatial separation of opioid and antagonist, emetic, or bittering agent	Addresses correct administration versus tampering
Claims 19-26	Manufacturing process	Covers mixing, heating, extrusion, pressure, inert gas, die configuration, chopping, pelletizing, and tableting
Claims 27-30	Product-by-process and process-related dosage forms	Extends product coverage to dosage forms made under specified process conditions
Claim 31	Specific opioids	Narrows the opioid class to named compounds and salts or esters

The central inventive concept is a mechanically strong, controlled-release opioid matrix that resists crushing and other tampering. The matrix uses 30% to 99.9% by weight of a polyalkylene oxide having a molecular weight of approximately 4 million to 15 million g/mol.

How broad is independent claim 1?

Claim 1 is broad in drug identity but narrow in formulation and manufacturing requirements.

A product must contain all of the following elements:

One or more opioids with abuse potential.
Optional auxiliary pharmaceutical substances.
Between 30% and 99.9% by weight of a polyalkylene oxide.
A polyalkylene oxide molecular weight from approximately 4 million to 15 million g/mol.
Hydroxypropylmethylcellulose, hydroxypropylcellulose, or hydroxymethylcellulose.
A controlled-release matrix in which the opioid is embedded.
A dosage form that is not multiparticulate.
Thermoforming by extrusion.
Extrusion at or above the polymer softening point and below 180°C.
A breaking strength of at least 500 N.
No discoloration attributable to the extrusion process.

The claim does not require a particular opioid dose, antagonist, wax, tablet shape, release profile, or commercial brand. It can cover oxycodone, morphine, hydromorphone, oxymorphone, and other opioids if the remaining limitations are satisfied.

The principal infringement risk is therefore not the opioid alone. The risk arises from reproducing the specified high-molecular-weight polymer matrix, cellulose component, extrusion conditions, and mechanical-strength result in a single dosage form.

What technical limitations control infringement?

Polyalkylene oxide concentration

The claimed matrix must contain 30% to 99.9% by weight of the polyalkylene oxide. A formulation with less than 30% is outside claim 1 as written, although another claim or related family patent could potentially apply.

The upper limit leaves little room for other formulation components. At 99.9%, only trace quantities of other materials could be present, so most commercial embodiments would fall somewhere in the middle of the range.

Molecular weight

The polyalkylene oxide must have a molecular weight of approximately 4 million to 15 million g/mol. The preferred practical embodiment is high-molecular-weight polyethylene oxide.

This limitation is important because lower-molecular-weight polyethylene oxide, ordinary polyethylene glycol, and many conventional hydrophilic matrix polymers would not satisfy the claim. Molecular-weight characterization can become a material issue in litigation because supplier specifications, lot testing, viscosity data, and analytical methodology may produce different results.

Cellulose component

The dosage form must contain hydroxypropylmethylcellulose, hydroxypropylcellulose, or hydroxymethylcellulose. The claim does not require a particular grade or concentration.

A formulation using only polyethylene oxide and no claimed cellulose derivative would not literally meet claim 1. A patentee could still pursue an equivalents theory, but the expressly recited cellulose limitation would make that argument more difficult.

Mechanical strength

The dosage form must have a breaking strength of at least 500 N. This is a substantial physical-strength threshold and is central to the abuse-deterrent function.

Testing conditions matter. Relevant variables include:

Tablet geometry
Diameter and thickness
Orientation during testing
Instrument calibration
Compression rate
Conditioning and storage humidity
Whether the result is measured on an intact tablet or another molded form

A generic or follow-on manufacturer could reduce literal infringement risk by using a formulation that fails the 500 N threshold, but that change could also reduce resistance to crushing and alter the product's regulatory profile.

Non-multiparticulate form

Claim 1 excludes multiparticulate dosage forms. A conventional single tablet is the clearest covered form. Pellets, beads, granules, or capsules containing numerous discrete particles may fall outside claim 1, although claims 19-26 expressly address pelletizing and other process formats.

This creates a claim-construction issue. The patent covers an extrudate that is singulated and pressed into tablets, but the final product requirement in claim 1 is "not being in multiparticulate form." A product containing many drug-containing units may require separate analysis under the process claims or related patent family members.

What opioid products fall within claim 31?

Claim 31 narrows claim 1 to specified opioid compounds:

Oxycodone
Oxymorphone
Hydromorphone
Morphine
The specified substituted phenolic opioid compound
Physiologically acceptable esters
Physiologically acceptable salts

Claim 31 is commercially relevant to abuse-deterrent products containing morphine, oxycodone, hydromorphone, or oxymorphone. It does not cover every opioid product because the claim depends on the structural and salt/ester limitations stated in claim 31.

The claim does not itself require an antagonist such as naloxone or naltrexone. Antagonist inclusion is addressed through dependent claims and the spatial-separation limitation in claim 18.

What abuse-deterrent features are protected?

Claims 6-18 cover several classes of tamper-response components.

Nasal and pharyngeal irritants

Claims 6-11 cover substances intended to cause burning, itching, sneezing, secretion, or related effects when the dosage form is manipulated for nasal or oral abuse.

The claim set identifies constituents associated with garlic, capsicum, ginger, mustard, pepper, turmeric, nutmeg, and related hot-substance drugs. Named compounds include capsaicinoids, piperine, gingerols, mustard-oil-related compounds, sulfide compounds, myristicin, elemicin, isoeugenol, and safrole.

Viscosity-increasing agents

Claim 12 covers materials that form a gel when extracted with a minimum amount of aqueous liquid. The listed materials include:

Sodium carboxymethylcellulose
Polyacrylic acid
Pectin
Sodium alginate
Guar flour
Carrageenan
Gellan gum
Xanthan gum
Tragacanth
Sodium hyaluronate
Various galactomannans and plant-derived gums

This limitation targets extraction and injection or nasal-administration abuse by increasing the viscosity of the extracted material.

Opioid antagonists

Claim 13 identifies naloxone, naltrexone, nalmefene, nalid, nalmexone, nalorphine, naluphine, and related physiologically acceptable compounds.

Claim 18 adds a structural arrangement under which the opioid is spatially separated from the antagonist, emetic, or bittering agent. The intended commercial logic is that correct administration does not activate the deterrent, while tampering or improper administration does.

Emetics, dyes, and bitter agents

Claims 15-17 cover ipecac-derived emetics, apomorphine, physiologically acceptable dyes, aromatic oils, fruit flavors, denatonium benzoate, and mixtures of bitter substances.

These claims are narrower and more formulation-specific than claim 1. A product containing only a conventional opioid and polyethylene oxide matrix would not necessarily meet them.

What manufacturing process does U.S. Patent 8,075,872 claim?

Claims 19-26 cover a hot-extrusion process with the following principal steps:

Mix the opioid, high-molecular-weight polyalkylene oxide, and one of the specified cellulose materials.
Heat the mixture in an extruder.
Maintain the temperature at or above the polymer softening point but below 180°C.
Apply sufficient force to produce at least 10 bar of pressure immediately before the material exits the die.
Singulate and shape the plastic extrudate.
Use an inert-gas atmosphere for specified processing steps.
Optionally cool, reheat, chop, pelletize, or press the extrudate into tablets.

Claim 26 specifies nitrogen as the inert gas. Claims 21 and 22 cover coextrusion, separate extrusion, and dies with one or more bores. Claims 23-25 cover chopping, calender-roll shaping, pelletizing, and tableting.

Why the 10-bar pressure limitation matters

The process claims are not limited to the final dosage form's composition. A manufacturer can potentially infringe even where the finished product is difficult to characterize compositionally if the process uses the claimed materials and operating parameters.

Process evidence may include:

Extruder batch records
Temperature profiles
Pressure logs
Die design
Nitrogen-flow records
Standard operating procedures
Equipment validation files
Development reports
Technical-transfer documents

The phrase "immediately before emerging from the outlet orifice" focuses the pressure limitation on the extrusion zone rather than general equipment pressure elsewhere in the machine.

How do the product and process claims interact?

The product claims and process claims create overlapping but distinct enforcement positions.

A manufacturer may face product-claim exposure when its final tablet has the claimed composition, strength, and extrusion characteristics. It may face process-claim exposure when it uses the specified high-molecular-weight polymer, cellulose derivative, sub-180°C extrusion, at least 10 bar pressure, and claimed shaping steps.

Claim 27 is a product-by-process claim. It covers a dosage form obtainable by the process of claim 19. Product-by-process enforceability generally turns on the product limitations and the controlling law in the relevant jurisdiction, not solely on whether the accused manufacturer uses the identical process.

Claims 28-30 reinforce the relationship between the dosage form and the extrusion pressure, cooling, singulation, and press-molding steps.

When did U.S. Patent 8,075,872 lose exclusivity?

Event	Date
Priority date	August 27, 2003
U.S. grant	December 13, 2011
Ordinary 20-year term endpoint	August 2024
Current practical status	Expired after the ordinary patent term, absent applicable term adjustment

The patent's expiration is distinct from FDA regulatory exclusivity. Patent expiry does not determine whether an opioid product remains approved, marketed, or subject to other patents.

The patent also does not create an automatic period of market exclusivity for every product containing an opioid. A product must fall within the claims, and the patent must have been listed or otherwise enforceable against the relevant product or process during the applicable term.

What is the Orange Book status of U.S. Patent 8,075,872?

The Orange Book lists patents for approved drug products when the sponsor submits patents that meet FDA listing requirements. A formulation patent is not automatically listed for every opioid product that uses similar technology.

The relevant regulatory questions are:

Whether the patent was submitted for a particular approved product
Whether FDA accepted it for Orange Book listing
Whether it was listed as a formulation, composition, or method-of-use patent
Whether the listing remained active before expiration
Whether an ANDA applicant had to make a Paragraph IV certification

Because the patent is directed to a broad class of abuse-deterrent opioid dosage forms rather than a single active ingredient, Orange Book relevance depends on product-specific listing history. FDA's Orange Book remains the controlling source for current listing and delisting information.[1]

As of the patent's ordinary 2024 expiration, it should not present a current Orange Book patent barrier unless a separate listed right or enforceable term adjustment existed.

Were Paragraph IV challenges likely under this patent?

A Paragraph IV challenge would have been relevant only if the patent was listed against a specific reference-listed drug. An ANDA applicant could allege that the patent was invalid, unenforceable, or not infringed.

The strongest Paragraph IV positions would likely have focused on:

Prior art describing polyethylene oxide controlled-release opioid matrices
Earlier abuse-deterrent dosage forms using antagonists or irritants
Lack of novelty in combining opioid matrices with cellulose derivatives
Obviousness of high-molecular-weight polyalkylene oxide with conventional extrusion
Indefiniteness of "without discoloration"
Enablement across the full 4 million to 15 million g/mol polymer range
Whether the product actually achieves 500 N breaking strength
Whether the extrusion pressure and temperature limitations are present

The patentee's strongest response would have been the combined relationship between high molecular weight, high polymer loading, extrusion conditions, physical strength, controlled release, and absence of discoloration. An isolated prior-art reference showing only one or two of those features would not necessarily anticipate claim 1.

Which competing patent estates matter?

Grünenthal abuse-deterrent matrix estate

The patent belongs to the broader Grünenthal abuse-deterrent dosage-form technology platform. Related family members and continuation filings should be reviewed together because claim scope may shift among composition, process, formulation, and product-by-process claims.

The estate's technical center is:

High-molecular-weight polyethylene oxide
Thermoforming and hot extrusion
Mechanical resistance to crushing
Controlled release
Antagonist or aversive-agent incorporation
Non-multiparticulate tablets

Purdue Pharma OxyContin estate

Purdue's abuse-deterrent OxyContin patents cover a different commercial product and a separate patent family. Frequently cited members include U.S. Patent Nos. 8,337,886, 8,808,750, and 9,073,933, among others.

The comparison is important:

Issue	U.S. 8,075,872	Purdue OxyContin estate
Core product	Broad opioid dosage-form class	Oxycodone-specific commercial formulation
Polymer concept	High-molecular-weight polyalkylene oxide matrix	Product-specific abuse-deterrent formulation technology
Key performance concept	At least 500 N breaking strength and controlled release	Resistance to crushing, dissolution, and abuse manipulation
Drug scope	Broad opioid class, narrowed in claim 31	Primarily oxycodone products
Regulatory relevance	Product-specific Orange Book listing required	Directly associated with OxyContin regulatory history

A product can potentially avoid one estate while implicating another. Freedom-to-operate analysis must map the exact formulation and manufacturing process against both estates.

Morphine and antagonist products

Products combining morphine with sequestered naltrexone, such as Embeda-type technology, raise separate questions involving antagonist placement, release behavior, and extraction resistance. Claim 18 of the '872 patent is relevant to spatial separation, but other product-specific patents may control the commercial product.

How strong was the patent estate?

The estate was strongest against a product that reproduced the full technical combination:

Opioid
30% to 99.9% high-molecular-weight polyalkylene oxide
Specified cellulose derivative
Single, non-multiparticulate dosage form
Extrusion below 180°C
Breaking strength of at least 500 N
Controlled-release matrix
No discoloration

Its strength was lower against:

Low-molecular-weight polymers
Polyalkylene oxide concentrations below 30%
Multiparticulate products
Cold-compressed tablets
Products lacking the specified cellulose derivative
Dosage forms below the 500 N strength threshold
Formulations made without extrusion
Products using alternative abuse-deterrence mechanisms

The patent's practical value was therefore high for a specific manufacturing and formulation platform but lower as a general monopoly over abuse-deterrent opioids.

What generic entry risks existed?

Before expiration, generic entry risk depended on whether the ANDA product matched the reference product's formulation and whether the patent was listed.

Potential launch scenarios included:

Paragraph III certification: The applicant accepted the patent and delayed launch until expiration.
Paragraph IV certification: The applicant challenged validity, enforceability, or infringement.
Non-infringing formulation: The applicant used a different polymer, lower polymer loading, alternative manufacturing process, or multiparticulate architecture.
Authorized generic or settlement launch: The applicant entered under an agreement with the brand owner.
Post-expiration launch: The applicant launched after the patent term ended, subject to other listed patents and FDA requirements.

For a generic opioid, formulation design-around was technically feasible but commercially difficult. Changing the polymer or compression process could affect dissolution, abuse-deterrence testing, bioequivalence, tablet robustness, and FDA labeling.

What manufacturing and intellectual-property barriers remain?

The expiration of the '872 patent does not eliminate all barriers to commercial entry.

Manufacturing barriers

A follow-on manufacturer still needs to control:

High-molecular-weight polyethylene oxide processing
Polymer feed consistency
Extruder torque and pressure
Thermal degradation
Color stability
Uniform opioid distribution
Tablet compression after cooling
Dissolution over the intended release period
Scale-up from laboratory to commercial extruders

High-molecular-weight polyethylene oxide can be difficult to feed, blend, and extrude consistently. Its rheology can cause equipment-specific processing windows.

Regulatory barriers

Abuse-deterrent opioids may require:

ANDA or 505(b)(2) approval
Comparative dissolution data
Bioequivalence data
Abuse-deterrence characterization
Labeling support
Control of opioid manufacturing and distribution
Compliance with FDA postmarket requirements

FDA's abuse-deterrent guidance evaluates physical and chemical manipulation, extraction, insufflation, injection, and oral abuse routes.[2]

Remaining IP barriers

A complete freedom-to-operate review should include:

Active ingredient patents
Salt and polymorph patents
Formulation patents
Abuse-deterrence patents
Method-of-use patents
Manufacturing-process patents
Device or packaging patents
Orange Book listings
Patent term adjustments
Settlement agreements
Foreign counterparts

Geographic protection was limited to the United States for U.S. Patent 8,075,872. Foreign equivalents, where granted, had separate terms and legal status.

What is the commercial significance of the patent?

The patent's commercial value was tied to abuse-deterrent controlled-release opioids, a category influenced by FDA labeling policy, opioid litigation, payer scrutiny, and product substitution.

The patent could protect a platform applicable to several opioid products rather than a single branded medicine. That made it potentially relevant to licensing, formulation partnerships, and technology transfers. Its economic exposure depended on the sales of products actually practicing the claims, not on total opioid-market revenue.

After expiration, the patent no longer supports ongoing U.S. royalty or exclusionary claims based solely on its own rights. Existing licenses may still contain contractual provisions, but the patent's expired status generally removes the patent-law basis for preventing unlicensed practice in the United States.

Key Takeaways

U.S. Patent 8,075,872 covers abuse-deterrent opioid dosage forms made by hot extrusion.
Claim 1 requires a high-molecular-weight polyalkylene oxide, generally polyethylene oxide, at 30% to 99.9% by weight.
The polymer must have a molecular weight of approximately 4 million to 15 million g/mol.
The product must contain a specified cellulose derivative and be a non-multiparticulate controlled-release dosage form.
The dosage form must have at least 500 N breaking strength and be produced without discoloration.
Claims 19-26 separately protect extrusion, pressure, inert-gas, singulation, pelletizing, and tableting processes.
Claims 6-18 cover irritants, viscosity agents, opioid antagonists, emetics, dyes, bitterants, and spatially separated deterrent components.
Claim 31 narrows the opioid to specified compounds including oxycodone, morphine, hydromorphone, and oxymorphone.
The patent's ordinary U.S. term expired in August 2024, absent applicable patent-term adjustment.
Biosimilar analysis is not relevant because the patent concerns small-molecule opioid dosage forms.
Current market-entry analysis must focus on other active formulation, method-of-use, manufacturing, and Orange Book-listed patents.

FAQs About U.S. Patent 8,075,872

Does U.S. Patent 8,075,872 cover all abuse-deterrent opioid tablets?

No. It covers products meeting the specific polymer, cellulose, extrusion, strength, controlled-release, and non-multiparticulate limitations. Abuse-deterrent tablets using different polymers or manufacturing processes may fall outside the claims.

Does a polyethylene oxide opioid tablet automatically infringe the patent?

No. The polyethylene oxide must generally fall within the claimed molecular-weight range and concentration range, and the product must satisfy the other limitations, including the cellulose component, extrusion conditions, controlled release, and 500 N breaking strength.

Can a multiparticulate opioid product avoid claim 1?

A multiparticulate product may avoid claim 1 because that claim expressly excludes multiparticulate dosage forms. Other process or related-family claims could still require separate review.

Is a product containing naloxone necessarily covered?

No. Naloxone is one of the listed antagonist options in claim 13, but infringement also requires the limitations of the claims from which claim 13 depends. The dosage form's polymer, cellulose, extrusion, strength, and release characteristics remain relevant.

Can a generic manufacturer use the disclosed extrusion process after patent expiration?

In the United States, the expired patent generally no longer prevents practice of its claimed process. The manufacturer must still evaluate other active patents, regulatory requirements, contractual restrictions, and foreign patent rights.

References

U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases
U.S. Food and Drug Administration. (2015). Abuse-deterrent opioids: Evaluation and labeling. https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/abuse-deterrent-opioids-evaluation-and-labeling
United States Patent and Trademark Office. (2011). U.S. Patent No. 8,075,872, Abuse-proofed dosage form.
United States Patent and Trademark Office. (2024). Patent term adjustment and patent term expiration guidance. https://www.uspto.gov/patents/laws/patent-term-adjustment-patent-term-extension-reinstatement sos.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Germany	103 36 400	Aug 06, 2003
Germany	10 2005 005 446	Feb 04, 2005

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	045352	⤷ Start Trial
Argentina	045353	⤷ Start Trial
Argentina	046994	⤷ Start Trial
Argentina	049083	⤷ Start Trial
Argentina	049839	⤷ Start Trial
Argentina	054328	⤷ Start Trial
Argentina	107985	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 8,075,872