US Patent 8,337,888: Oxycodone Abuse-Deterrent Formulation Scope, Expiration, and Patent Landscape

US Patent 8,337,888 covers controlled-release oral oxycodone dosage forms that combine oxycodone, polyethylene oxide, extended therapeutic duration, and viscosity formation when the dosage form is dissolved in a small volume of aqueous liquid. The claims target abuse-deterrent behavior, particularly resistance to crushing, dissolution, heating, and injection-oriented preparation.

The patent is directed to a formulation platform rather than a single tablet strength. Its principal technical limitation is the combination of at least 12 hours of therapeutic effect with a polyethylene oxide-containing matrix that develops measurable viscosity after tampering.

What does US Patent 8,337,888 protect?

US 8,337,888 protects an oral controlled-release dosage form containing:

Approximately 2.5 mg to 320 mg of oxycodone or an acceptable salt;
Polyethylene oxide as a gelling agent;
A viscosity of at least approximately 10 centipoise after dissolution in 0.5 mL to 10 mL of aqueous liquid; and
At least 12 hours of therapeutic effect after oral administration.

Independent claim 1 establishes the core combination. The patent does not claim oxycodone alone, polyethylene oxide alone, or a conventional extended-release oxycodone tablet without the specified tamper-response characteristics.

The commercial significance of the claim is that the dosage form must satisfy both ordinary oral controlled-release performance and a tamper-resistance test. A product that forms a viscous mass when crushed and mixed with water but does not provide at least 12 hours of therapeutic effect would not meet the full combination in claim 1.

Core claim elements

Claim element	Scope
Active ingredient	Oxycodone or pharmaceutically acceptable salt
Oxycodone quantity	About 2.5 mg to about 320 mg
Release profile	Therapeutic effect for at least about 12 hours
Matrix component	Polyethylene oxide
Tamper condition	Dissolution in about 0.5 mL to about 10 mL aqueous liquid
Minimum viscosity	At least about 10 cP
Enhanced viscosity option	At least about 60 cP
Preferred liquid	Water
Preferred tampering	Crushing followed by dissolution
Heating embodiment	Dissolution with heating above 45°C

How do claims 2 through 10 narrow the polyethylene oxide scope?

Claims 2 through 4 define weight ratios between polyethylene oxide and oxycodone. Claim 2 is the broadest ratio limitation, while claims 3 and 4 progressively narrow the range.

Claim	Polyethylene oxide:oxycodone ratio
2	About 1:40 to 40:1
3	About 1:1 to 30:1
4	About 2:1 to 10:1

Claims 8 through 10 specify the molecular weight of the polyethylene oxide:

Claim	Polyethylene oxide molecular weight
8	About 1,000,000 to 10,000,000
9	About 1,000,000 to 7,000,000
10	About 5,000,000

These limitations are important because high-molecular-weight polyethylene oxide is responsible for rapid swelling and viscosity formation in a small volume of water. A competing formulation using a lower-molecular-weight polymer, another gelling agent, or a different abuse-deterrent mechanism may avoid the literal scope of claims 8 through 10, while still requiring analysis under the broader claims.

The claims use approximate numerical language. In an infringement dispute, the meaning of terms such as “about,” “effective amount,” and “at least” would depend on the specification, prosecution history, test method, and the accused product’s measured characteristics.

What oxycodone strengths are protected?

Claims 11 through 16 focus on oxycodone hydrochloride and identify the strengths most closely associated with commercial controlled-release oxycodone products.

Claim	Oxycodone hydrochloride amount
11	Oxycodone hydrochloride generally
12	About 10 mg to about 80 mg
13	About 10 mg
14	About 20 mg
15	About 40 mg
16	About 80 mg

The claims are drafted broadly enough that the listed strengths are dependent embodiments rather than the entire scope of the patent. Claim 1 reaches dosage forms containing up to approximately 320 mg of oxycodone or its salt, subject to the other requirements.

For a product containing 10 mg, 20 mg, 40 mg, or 80 mg of oxycodone hydrochloride, the most relevant claim analysis would focus on:

Whether the product uses polyethylene oxide;
The amount and molecular weight of that polymer;
Whether the crushed or dissolved product reaches the claimed viscosity;
Whether the product provides at least 12 hours of therapeutic effect; and
Whether the relevant ratios fall within claims 17 through 22.

What ratios are protected for oxycodone hydrochloride products?

Claims 17 through 22 provide a graduated ratio structure:

Claim	Polyethylene oxide:oxycodone hydrochloride ratio
17	About 1:40 to 40:1
18	About 1:1 to 30:1
19	About 2:1 to 10:1
20	About 1:15 to 15:1
21	About 1:8 to 8:1
22	About 1:3 to 3:1

Claims 17 through 22 are narrower than claim 11 because they require oxycodone hydrochloride and a specified polymer-to-drug ratio. The overlapping ranges create multiple fallback positions. A formulation outside claim 22 may still fall within claims 17, 18, or 19, depending on the actual ratio.

The practical consequence is that a generic developer cannot rely solely on a different tablet strength to avoid the patent. The polymer-to-oxycodone ratio must be evaluated separately for each strength.

What tampering methods are covered?

Claim 23 expressly covers viscosity obtained after crushing and dissolution in aqueous liquid. Claim 24 covers dissolution with heating above 45°C.

These claims address preparation techniques commonly associated with attempts to defeat controlled release:

Crushing the tablet;
Dissolving crushed material in water or another aqueous liquid;
Using a small liquid volume;
Heating the mixture; and
Preparing a viscous suspension that is difficult to draw into a syringe.

Claim 1 itself does not expressly require crushing or heating. It requires viscosity after the dosage form is subjected to tampering by dissolution. Claims 23 and 24 provide more specific embodiments and may be easier to apply when testing demonstrates the claimed result under those conditions.

The patent therefore covers more than mechanical crush resistance. Its claim structure addresses matrix behavior after dissolution, including the formation of a high-viscosity material in a limited volume of liquid.

How strong is the patent estate represented by US 8,337,888?

The individual patent has a technically focused claim set. Its strength is concentrated in the combination of:

Oxycodone;
A controlled-release oral dosage form;
Polyethylene oxide;
A defined viscosity response;
A small aqueous volume; and
A 12-hour therapeutic duration.

The estate is stronger against products that reproduce the same polyethylene oxide matrix and abuse-deterrent mechanism. It is weaker against products that use a different polymer, a non-gelling barrier technology, an insoluble matrix, a physical tablet structure, or a different route of controlled release.

Principal strength factors

Factor	Assessment
Product identity	Strong for polyethylene oxide oxycodone matrices
Dosage strengths	Broad, with specific 10 mg to 80 mg claims
Abuse-deterrent function	Strong where viscosity testing is reproducible
Polymer limitation	Narrows scope to polyethylene oxide-containing products
Functional language	Creates testing and claim-construction issues
Design-around potential	Moderate, especially with non-PEO technologies
Biosimilar relevance	None; oxycodone is a small-molecule drug
Manufacturing barrier	Moderate if the formulation relies on high-MW PEO processing

What is the Orange Book status of US 8,337,888?

The patent is associated with the controlled-release oxycodone product franchise, including OxyContin-related regulatory and patent activity. The relevant FDA product is OxyContin extended-release tablets, NDA 022272, held by Purdue Pharma-related entities. FDA Orange Book listings must be evaluated by NDA, patent-use code, and the specific reporting date because listed patents and use codes can change over time.[2]

An Orange Book listing does not establish validity or infringement. It affects the generic approval pathway by requiring an ANDA applicant to address the listed patent through:

Paragraph I certification;
Paragraph II certification;
Paragraph III certification; or
Paragraph IV certification.

For a listed patent that has expired, the Orange Book record may remain historically relevant, but it no longer creates a current patent-based 30-month stay for a newly filed Paragraph IV challenge.

When did US 8,337,888 lose exclusivity?

US 8,337,888 was granted on December 25, 2012. Its ordinary patent term was tied to the relevant family priority and filing dates. Public patent records associate the OxyContin controlled-release formulation family with a nominal expiration period in 2025, subject to patent-term adjustment, terminal disclaimers, and any applicable regulatory extension.[1]

The commercial exclusivity analysis has two separate components:

Exclusivity type	Relevance
Patent exclusivity	Determined by the enforceable expiration date of the patent and related family patents
FDA regulatory exclusivity	Determined by NDA approval, exclusivity codes, and product-specific FDA records
Orange Book protection	Depends on whether the patent remains listed and whether an ANDA certification triggers statutory provisions
Market exclusivity	Also affected by settlements, authorized generics, and approval timing

US 8,337,888 should not be analyzed in isolation. Related OxyContin formulation patents may have different claim categories, including controlled-release composition, manufacturing process, formulation architecture, and method-of-use claims. A generic product may avoid this patent yet remain exposed to another patent in the same family or product estate.

Which companies have challenged oxycodone extended-release patents?

The principal ANDA challengers in the controlled-release oxycodone market have included major generic manufacturers seeking approval for oxycodone extended-release tablets. Relevant litigation historically involved Purdue and its affiliates against generic companies pursuing products that could compete with OxyContin.

The most important legal issue in such cases is usually not whether the generic contains oxycodone. It is whether the proposed formulation practices the specific claimed combination of polyethylene oxide, controlled release, and tamper-induced viscosity.

A Paragraph IV certification can create patent litigation even when the generic applicant asserts non-infringement, invalidity, or both. Typical invalidity theories for this type of patent include:

Anticipation by an earlier controlled-release oxycodone formulation;
Obviousness based on opioid matrix systems and high-molecular-weight polymers;
Lack of written description for broad ratio and viscosity ranges;
Lack of enablement across the full 2.5 mg to 320 mg dosage range;
Indefiniteness involving “about,” “effective amount,” or test conditions; and
Inability to reproduce the claimed viscosity under a sufficiently defined protocol.

The supplied claims alone do not establish the outcome of any particular Paragraph IV case. Case-specific analysis requires the relevant complaint, ANDA notice letter, claim construction orders, expert testing, settlement terms, and final judgment.

What settlement agreements affect generic launch timing?

OxyContin-related patent settlements can determine whether a generic product launches before or after nominal patent expiration. Settlement terms may include:

A licensed entry date;
An authorized generic arrangement;
Restrictions on commercialization;
A covenant not to sue;
Withdrawal or dismissal of litigation; or
Entry conditioned on regulatory approval.

A settlement does not necessarily eliminate formulation risk. A license may cover a particular product, strength, or formulation but not a later product modification. Conversely, a generic company may secure launch rights while still needing to address separate patents listed for the same NDA.

The economic value of a settlement depends on the remaining patent term, expected generic price erosion, the number of approved competitors, opioid market controls, and the availability of an authorized generic.

What generic entry risks exist for US 8,337,888?

Generic entry risk is highest for a product that duplicates the commercial OxyContin matrix using high-molecular-weight polyethylene oxide. That product would face direct exposure under the core composition and viscosity claims.

Generic design	Risk under US 8,337,888
Same PEO matrix and similar oxycodone strengths	High
Same PEO matrix but different drug-to-polymer ratio	Moderate to high
PEO with a different molecular weight	Depends on claims 1-7 and 11-24
Non-PEO gelling polymer	Lower literal infringement risk
Non-gelling abuse-deterrent technology	Lower
Immediate-release or short-duration product	Outside the 12-hour limitation, but not necessarily outside other patents
Different active opioid	Outside the oxycodone limitation

The principal design-around route is to avoid polyethylene oxide while preserving controlled release and abuse deterrence. That approach may create separate regulatory and technical risks, including altered pharmacokinetics, dose dumping, extractability, tablet manufacturability, and comparative abuse-deterrence performance.

Does US 8,337,888 create biosimilar risk?

No. Oxycodone is a chemically synthesized small-molecule active ingredient. The relevant pathway is an ANDA under section 505(j) of the Federal Food, Drug, and Cosmetic Act, not a biosimilar application under the Public Health Service Act.

The competitive risks are generic substitution, Paragraph IV litigation, authorized generic entry, formulation design-arounds, and post-expiration price erosion. Biosimilar interchangeability and biologic manufacturing issues do not apply.

What manufacturing and intellectual-property barriers remain?

The patent creates manufacturing barriers where the product depends on:

Uniform distribution of high-molecular-weight polyethylene oxide;
Reliable compression of a viscous polymer matrix;
Consistent dissolution and release behavior;
Reproducible viscosity after crushing and extraction;
Control of polymer hydration;
Stable tablet hardness and friability; and
Strength-specific polymer-to-oxycodone ratios.

High-molecular-weight polyethylene oxide can complicate blending, granulation, compression, dissolution testing, and scale-up. A product may meet the release profile but fail the viscosity requirement, or meet the abuse-deterrent test but fail bioequivalence requirements.

The patent’s claims also create a product-testing issue. A complete freedom-to-operate analysis requires testing the finished dosage form under the relevant liquid volumes, temperatures, crushing conditions, dissolution times, and viscosity measurement methods.

Key Takeaways

US 8,337,888 covers oxycodone controlled-release oral dosage forms using polyethylene oxide to create viscosity after tampering.
Claim 1 requires oxycodone, polyethylene oxide, at least 12 hours of therapeutic effect, and at least approximately 10 cP viscosity in a small aqueous volume.
Dependent claims cover water, 1 mL to 3 mL liquid volumes, at least 60 cP viscosity, crushing, heating above 45°C, high-molecular-weight polyethylene oxide, and oxycodone hydrochloride strengths from 10 mg to 80 mg.
The strongest infringement risk is for generic products that reproduce the OxyContin-style polyethylene oxide matrix.
Non-PEO abuse-deterrent technologies offer the clearest design-around path, subject to separate patents and FDA requirements.
The patent’s nominal term was associated with the 2025 expiration period, but enforceability depends on the recorded term, patent-term adjustment, terminal disclaimers, and related patents.
Oxycodone has no biosimilar pathway. Generic competition proceeds through the ANDA framework.
Orange Book status, Paragraph IV litigation, settlement rights, and related OxyContin patents must be reviewed together rather than treating US 8,337,888 as the entire product estate.

FAQs

Does US 8,337,888 cover all extended-release oxycodone tablets?

No. The claims require polyethylene oxide and a specified viscosity response after dissolution, in addition to controlled-release oxycodone characteristics.

Can a generic avoid the patent by changing the oxycodone strength?

Not necessarily. Claims 1 through 4 cover broad amounts and ratios, while claims 12 through 16 identify specific oxycodone hydrochloride strengths. Strength changes must be assessed with the polymer ratio and measured viscosity.

Does using polyethylene oxide automatically infringe US 8,337,888?

No. Polyethylene oxide use alone is insufficient. The product must satisfy the relevant combination of active ingredient, controlled-release duration, polymer conditions, ratio or molecular-weight limitations where applicable, and viscosity limitations.

Is a 12-hour oxycodone product outside the patent if it resists crushing but does not become viscous?

Potentially, depending on the other claim elements. The core claims require a viscosity response. Crush resistance based on a different mechanism does not by itself satisfy the polyethylene oxide viscosity claims.

Are OxyContin formulation patents still commercially relevant after the 2025 term period?

Yes, for historical litigation, validity analysis, settlement interpretation, product development, and related-family review. Current launch risk depends on the enforceable status of each patent, Orange Book listings, regulatory exclusivity, and any continuing patent rights.

References

United States Patent and Trademark Office. (2012). United States Patent No. 8,337,888, controlled release oxycodone formulations.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (n.d.). OxyContin prescribing information and product labeling. Purdue Pharma L.P.
U.S. Food and Drug Administration. (2017). Abuse-deterrent opioids: Evaluation and labeling guidance for industry.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	2002319774	⤷ Start Trial
Brazil	0212019	⤷ Start Trial
Brazil	0212020	⤷ Start Trial
Canada	2455420	⤷ Start Trial
Canada	2456322	⤷ Start Trial
Germany	20220910	⤷ Start Trial
Germany	20220917	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,337,888

Summary for Patent: 8,337,888