Details for Patent: 8,894,988

Which drugs does patent 8,894,988 protect, and when does it expire?

Patent 8,894,988 protects OXYCONTIN and is included in one NDA.

This patent has two hundred and twenty-one patent family members in forty countries.

Summary for Patent: 8,894,988

Title:	Tamper resistant dosage forms
Abstract:	The present invention relates to pharmaceutical dosage forms, for example to a tamper resistant dosage form including an opioid analgesic, and processes of manufacture, uses, and methods of treatment thereof.
Inventor(s):	William H. McKenna, Richard O. Mannion, Edward P. O'Donnell, Haiyong H. Huang
Assignee:	Purdue Pharma LP , Purdue Pharmaceuticals LP
Application Number:	US13/900,963
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 8,894,988
Patent Claim Types: see list of patent claims	Composition; Process; Device; Dosage form;

US Patent 8,894,988: Oxycodone Extended-Release Tablet Claims, Patent Scope and Generic Entry Risk

US Patent No. 8,894,988 protects a manufacturing process and product configuration for abuse-deterrent, extended-release opioid tablets made with high-molecular-weight polyethylene oxide, or PEO. The central limitation is a cured, shaped tablet containing approximately 4,000,000-molecular-weight PEO and an opioid, with curing at about 60 to 90°C after tablet formation.

The patent is most commercially relevant to Purdue Pharma’s reformulated OxyContin products. Its practical value depends on whether a competing product uses the same high-molecular-weight PEO matrix, comparable oxycodone strengths, and post-compression thermal curing. The reported Orange Book expiration date for the relevant OxyContin patent family was May 28, 2025, subject to the patent’s official term adjustments and regulatory listing status.

What does US Patent 8,894,988 protect?

The patent covers both the finished tablet and the process used to manufacture it. The claims are structured around five technical elements:

1. A shaped tablet containing an extended-release matrix.
2. At least one PEO polymer with an approximate rheological molecular weight of 4,000,000.
3. Oxycodone or another opioid analgesic.
4. Tablet formation before curing.
5. Thermal curing of the shaped tablet at approximately 60 to 90°C for 15 minutes to 10 hours.

The claims are not limited solely to oxycodone. Claim 1 targets specified oxycodone strengths, while claim 6 extends the formulation concept to opioid analgesics generally.

Core claim architecture

Claim group	Active ingredient	PEO requirement	Curing requirement	Additional limitation
Claims 1-5	Oxycodone or salt	At least 79%, 72%, 57% or 54%, depending on dose	60-90°C; 15 minutes-10 hours	Dosage-strength-specific
Claims 6-8	Opioid analgesic	At least 79%	60-90°C; 15 minutes-10 hours	Broad opioid formulation
Claims 9-14	Hydrocodone, hydromorphone, oxymorphone or morphine	At least 79%	Claims depend from claim 6	Active-specific species claims
Claims 15-18	Oxycodone	Same dose/PEO thresholds as claim 1	Inherited from claim 1	Repeats composition limitations
Claims 19-23	Oxycodone	Same dose/PEO thresholds	Compression expressly required	Process-specific
Claims 24-26	Oxycodone or opioid	As incorporated from parent claims	Convection curing	Equipment/process limitation
Claims 27-30	Oxycodone or opioid	As incorporated from parent claims	Curing required	At least 1% or 2% density reduction

What are the strongest independent claims in US 8,894,988?

Claims 1 and 6 are the principal independent product-and-process claims.

Claim 1 is commercially narrower but more directly relevant to OxyContin. It requires:

• Oxycodone or a pharmaceutically acceptable salt;
• approximately 4,000,000-molecular-weight PEO;
• dose-specific oxycodone quantities;
• minimum PEO percentages tied to dose;
• shaping the blend into a tablet; and
• curing the tablet after shaping.

Claim 6 is broader as to the active ingredient. It covers an opioid analgesic with at least 79% PEO, without the dose-specific oxycodone tiers in claim 1. Claims 9 through 14 identify hydrocodone, hydromorphone, oxymorphone and morphine embodiments.

Claims 19 and 24 through 30 add process limitations. These claims may be easier to design around because they require particular manufacturing steps, such as compression, convection curing or a measurable reduction in density.

How do the oxycodone dose limitations affect infringement?

The claim divides oxycodone formulations into four PEO thresholds:

Oxycodone amount	Minimum PEO concentration
5, 7.5, 10, 15, 20 or 30 mg	At least 79% by weight
40 mg	At least 72% by weight
60 mg	At least 57% by weight
80 mg	At least 54% by weight

The claim language is cumulative. A product must satisfy the applicable dose and PEO threshold, in addition to the polymer identity, tablet-shaping and curing requirements.

The use of percentage thresholds creates a direct formulation-design pathway around the patent. A competing manufacturer could assess:

• a lower concentration of the specified PEO;
• a different polymer molecular-weight grade;
• a mixture of PEO grades that does not meet the claimed rheological characterization;
• a non-thermal curing process;
• curing before tablet shaping;
• a different dosage strength;
• a non-tablet dosage form; or
• a matrix using a polymer other than PEO.

A design-around would need to be evaluated against the full claim language and the doctrine of equivalents. Changing only the trade name or supplier of the PEO would not ordinarily avoid the claim if the material has the claimed functional molecular-weight characteristic.

What does “approximate molecular weight of 4,000,000” mean?

The claims define the PEO by rheological measurements rather than by a conventional absolute molecular-weight test. That distinction is important.

A competing product could contain a polymer marketed with a nominal molecular weight different from 4,000,000 but still exhibit the rheological behavior covered by the claim. Conversely, a product labeled as “4,000,000 molecular weight” may not satisfy the claim if its measured rheological properties fall outside the relevant range.

The patent therefore creates an analytical issue involving:

• polymer supplier specifications;
• rheological test methodology;
• viscosity or flow behavior;
• lot-to-lot variation;
• molecular-weight distribution;
• polymer hydration and processing history; and
• whether the claim requires a specific numerical measurement or an approximate characterization.

For freedom-to-operate work, the polymer’s certificate of analysis is not sufficient by itself. The relevant polymer should be tested under the method disclosed or contemplated by the patent.

How does the curing step limit the patent scope?

The curing step is the patent’s principal process limitation. The tablet must be shaped first and then subjected to a temperature of approximately 60 to 90°C for 15 minutes to 10 hours.

Dependent claims narrow the process to:

• 30 to 90 minutes;
• 62 to 90°C;
• convection curing; and
• curing that reduces tablet density by at least 1% or 2%.

This sequencing matters. A process that heats the powder blend before compression, but does not cure the already shaped tablet, presents a stronger noninfringement position against claims requiring post-shaping curing.

The same issue applies to drying. Ordinary removal of residual moisture at an elevated temperature could potentially be characterized as curing if the process produces the claimed tablet and falls within the temperature and time ranges. Manufacturing records should therefore distinguish:

• pre-compression heating;
• post-compression curing;
• coating-drying operations;
• environmental conditioning;
• storage-related changes; and
• deliberate thermal treatment intended to alter matrix properties.

What formulations are protected by US 8,894,988?

The patent protects high-PEO extended-release matrix tablets containing opioid actives. The expressly identified opioid categories include:

Active	Claim coverage
Oxycodone	Claims 1-5, 15-23 and related claims
Hydrocodone	Claim 9
Hydromorphone	Claims 10-11
Oxymorphone	Claims 12-13
Morphine	Claim 14

The claims permit pharmaceutically acceptable salts. Oxycodone hydrochloride is specifically identified in claim 2. Hydromorphone hydrochloride and oxymorphone hydrochloride are identified in claims 11 and 13.

The patent does not require a particular coating in the independent claims. Claims 5 and 8 expressly permit a coating applied before or after curing. A coating therefore does not remove a formulation from the claim scope.

What is the relationship to reformulated OxyContin?

The claim set closely tracks the technical characteristics associated with reformulated OxyContin: a high-PEO matrix, extended release, tablet shaping and post-formation thermal curing. The reformulated product was developed to make crushing and dissolution more difficult than with the original oxycodone formulation.

The patent does not require every abuse-deterrent characteristic associated with the commercial product. It does not expressly require:

• a particular tablet shape;
• a particular color;
• a particular coating;
• a specific dissolution profile;
• a defined abuse-deterrence test result;
• a particular manufacturing site; or
• a particular brand.

Its scope is therefore formulation- and process-driven rather than brand-driven.

What was the Orange Book status of US 8,894,988?

US 8,894,988 was associated with the patent estate for reformulated OxyContin and was part of the broader patent framework covering extended-release oxycodone tablets. The Orange Book listing must be assessed together with the product’s approved strengths, use codes and other listed patents.[2]

The relevant commercial patent dates are summarized below.

Item	Reported status
Patent	US 8,894,988
Patent holder associated with OxyContin estate	Purdue Pharma L.P. and affiliated entities
Product relevance	Reformulated extended-release oxycodone
Core technology	High-PEO cured opioid matrix tablet
Reported Orange Book expiration	May 28, 2025
Regulatory pathway	NDA-based extended-release oxycodone product
Likely generic pathway	ANDA with Paragraph IV certification or post-expiration certification

The expiration date is distinct from FDA exclusivity. Patent expiration does not itself establish when an ANDA may launch. Regulatory exclusivity, court injunctions, settlements and any applicable pediatric extension can affect the effective entry date.

When did US 8,894,988 lose exclusivity?

The reported patent expiration date was May 28, 2025. The practical loss of exclusivity depended on:

• whether the patent remained enforceable after any terminal disclaimer or term adjustment;
• whether a pediatric extension applied;
• whether the patent was listed for the specific strength or indication challenged;
• whether a generic applicant obtained 180-day first-filer exclusivity;
• whether litigation produced a stay or injunction; and
• whether a settlement agreement delayed commercial launch.

The patent’s expiration should not be treated as proof that a generic could immediately market an identical product. FDA approval, controlled-substance scheduling compliance, manufacturing readiness and litigation resolution remain separate requirements.

Which companies challenged the OxyContin patent estate?

The OxyContin patent estate was challenged through ANDA litigation involving generic pharmaceutical companies, including Teva Pharmaceuticals and other major generic manufacturers. Public OxyContin litigation records include proceedings under the Hatch-Waxman framework involving Purdue and generic applicants.

Paragraph IV litigation generally tests one or more of the following positions:

• noninfringement based on different polymer concentration or grade;
• noninfringement based on the absence of post-compression curing;
• invalidity for anticipation;
• invalidity for obviousness;
• indefiniteness of the rheological molecular-weight limitation;
• lack of written description for the dose-specific PEO thresholds; and
• unenforceability based on prosecution conduct or inequitable conduct allegations.

A Paragraph IV certification is not itself proof that the patent is invalid. It creates a statutory basis for patent litigation and can trigger a 30-month FDA approval stay under the Hatch-Waxman Act.[3]

What patent litigation affects US 8,894,988?

The relevant litigation risk is concentrated in two categories.

Validity risk

The patent combines known extended-release opioid matrices with high-molecular-weight PEO and thermal treatment. An invalidity challenge would likely focus on whether the claimed combination was obvious in light of:

• prior PEO matrix tablets;
• prior opioid extended-release formulations;
• thermal curing or annealing methods;
• abuse-deterrent dosage-form references; and
• routine optimization of polymer concentration and processing temperature.

The dose-specific PEO thresholds could support a nonobviousness argument if the patent demonstrates an unexpected relationship between dose loading and polymer concentration. The strength of that argument depends on the comparative dissolution, crush-resistance and abuse-deterrence data in the patent record.

Infringement risk

Infringement risk is highest for a product that uses all of the following:

• oxycodone hydrochloride;
• one of the specified oxycodone strengths;
• at least the applicable PEO percentage;
• approximately 4,000,000-molecular-weight PEO;
• compression or shaping into a tablet; and
• post-compression curing at 60 to 90°C.

Risk is lower where the product uses a different matrix polymer, a lower PEO load, a different thermal process or a non-tablet dosage form.

How strong is the patent estate?

The patent is strongest against a close copy of the reformulated OxyContin manufacturing process. It is less dominant across the entire extended-release opioid market because the claims are tied to a specific polymer system and curing sequence.

Risk factor	Assessment
Product overlap with reformulated OxyContin	High
Dependence on high-molecular-weight PEO	High
Dependence on post-shaping thermal curing	High
Coverage of alternative polymers	Low
Coverage of non-tablet formulations	Low
Coverage of other opioids	Moderate, subject to claim 6 limitations
Ability to design around by process change	Moderate to high
Relevance after reported 2025 expiration	Primarily historical, unless term adjustment or related patents apply

The broader OxyContin estate included other patents directed to abuse-deterrent properties, extended-release formulations and related manufacturing concepts. A product that avoids US 8,894,988 may still encounter separate patent claims.

What generic launch scenarios existed?

Scenario 1: Launch after patent expiration

This is the lowest patent-risk scenario if the generic product receives FDA approval and no related unexpired patents or exclusivity periods block launch.

Scenario 2: Paragraph IV launch before expiration

A first filer could launch before expiration after prevailing in litigation, obtaining a favorable settlement date, or accepting potential damages exposure. Commercial launch would carry significant risk if the product practiced the claimed PEO-and-curing combination.

Scenario 3: Noninfringing reformulation

A generic applicant could develop a formulation using a different polymer grade, a lower PEO concentration or a different manufacturing sequence. This approach reduces infringement exposure but requires separate bioequivalence, abuse-deterrence and manufacturing validation work.

Scenario 4: At-risk launch

An applicant could launch after FDA approval while litigation remained unresolved. For a controlled-release opioid, the commercial and injunction risks would be substantial because a later finding of infringement could result in damages, an injunction or product withdrawal.

What manufacturing and IP barriers remain?

The most important manufacturing barrier is reproducing the matrix consistently at high PEO concentrations. High-molecular-weight PEO can create problems involving:

• poor powder flow;
• segregation;
• compression-force sensitivity;
• tablet weight variation;
• sticking and picking;
• thermal uniformity;
• curing-time control;
• dissolution variability; and
• scale-up from development equipment to commercial convection ovens.

The patent’s density-reduction claims create another process-control issue. A manufacturer seeking to avoid claims 27 through 30 would need reliable pre- and post-cure density measurements. Those measurements must account for tablet dimensions, coating, moisture loss and test conditions.

How does US 8,894,988 compare with alternative opioid patent estates?

Patent estate type	Primary protection	Design-around potential
US 8,894,988	High-PEO cured opioid matrix tablets	Moderate to high
Conventional extended-release opioid patents	Release profile, dosage form or excipient system	Variable
Abuse-deterrent coating patents	Coating composition and mechanical properties	Moderate
Manufacturing-process patents	Granulation, compression, curing or coating sequence	Often high if process can be changed
Method-of-use patents	Treatment indication or dosing regimen	Depends on label and physician use
Biologic patents	Not applicable to oxycodone tablets	Not applicable

Biosimilar risk is not relevant to this patent because oxycodone, hydrocodone, morphine and related products are small-molecule drugs. The competitive threat is from ANDA-based generic products, not biosimilars.

Key Takeaways

• US 8,894,988 covers cured extended-release opioid tablets using approximately 4,000,000-molecular-weight PEO.
• The most important limitations are the PEO concentration, opioid identity, tablet formation and post-shaping thermal curing.
• Oxycodone coverage is dose-specific, with PEO thresholds ranging from at least 79% for lower strengths to at least 54% for 80 mg tablets.
• The patent also covers hydrocodone, hydromorphone, oxymorphone and morphine embodiments.
• Coating does not avoid the claims because the patent expressly permits coating before or after curing.
• Claims requiring convection curing or density reduction are narrower and more vulnerable to process design-arounds.
• The patent was associated with the reformulated OxyContin patent estate.
• The reported Orange Book expiration date was May 28, 2025.
• Generic risk depends on the complete OxyContin patent estate, not US 8,894,988 alone.
• The principal freedom-to-operate variables are polymer grade, PEO concentration, curing sequence, curing temperature and dosage-form design.

FAQs

Does US 8,894,988 cover all oxycodone extended-release tablets?

No. It covers tablets meeting the specified PEO, dose, shaping and curing limitations. Extended-release oxycodone products using different polymers or manufacturing processes may fall outside the claims.

Can a generic avoid the patent by using a different PEO supplier?

Not necessarily. Supplier identity is not the controlling limitation. A polymer from another supplier may still infringe if it has the claimed rheological molecular-weight characteristic and is used at the required concentration.

Does tablet coating avoid infringement?

No. Claims 5 and 8 expressly contemplate a tablet coated before or after curing. A coating alone does not remove an otherwise infringing product from the claims.

Are hydromorphone and oxymorphone products covered?

They can be. Claims 10 through 13 expressly identify hydromorphone, hydromorphone hydrochloride, oxymorphone and oxymorphone hydrochloride, provided the other limitations of the incorporated claims are met.

Is a product outside the patent if it is heated after compression for drying?

Not automatically. Post-compression heating can raise infringement issues if it falls within the claimed temperature and time ranges and produces the claimed cured tablet. The purpose assigned to the heating step is less important than the actual process conditions and resulting product.

References

1. United States Patent and Trademark Office. (2014). U.S. Patent No. 8,894,988, Cured shaped articles and methods of making same.
2. U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations: Orange Book.
3. U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application process and patent certifications.
4. U.S. Code, 21 U.S.C. § 355(j). (2024). Abbreviated applications for new drugs.
5. Purdue Pharma L.P. (2010). OxyContin extended-release tablets prescribing information. FDA-approved labeling.

Drugs Protected by US Patent 8,894,988

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Knoa Pharma	OXYCONTIN	oxycodone hydrochloride	TABLET, EXTENDED RELEASE;ORAL	022272-001	Apr 5, 2010		RX	Yes	No	8,894,988		Y
Knoa Pharma	OXYCONTIN	oxycodone hydrochloride	TABLET, EXTENDED RELEASE;ORAL	022272-002	Apr 5, 2010		RX	Yes	No	8,894,988		Y
Knoa Pharma	OXYCONTIN	oxycodone hydrochloride	TABLET, EXTENDED RELEASE;ORAL	022272-003	Apr 5, 2010		RX	Yes	No	8,894,988		Y
Knoa Pharma	OXYCONTIN	oxycodone hydrochloride	TABLET, EXTENDED RELEASE;ORAL	022272-004	Apr 5, 2010		RX	Yes	No	8,894,988		Y
Knoa Pharma	OXYCONTIN	oxycodone hydrochloride	TABLET, EXTENDED RELEASE;ORAL	022272-005	Apr 5, 2010		RX	Yes	Yes	8,894,988		Y

International Family Members for US Patent 8,894,988

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	062511
Argentina	103463
Argentina	109796
Argentina	109797
Austria	11571