United States Patent 6,488,963: Scope, Claims, Expiration, and Pharmaceutical Patent Landscape

U.S. Patent No. 6,488,963 covers non-film controlled-release pharmaceutical formulations using high-molecular-weight poly(ethylene oxide), or PEO, as the release-controlling polymer. The claims also cover plasticized formulations, lower-molecular-weight PEO or polyethylene glycol additives, and hot-melt extrusion.

The patent is a platform formulation patent rather than a drug-specific patent. Its commercial relevance depends on whether a product uses the claimed PEO molecular-weight range, drug-to-polymer ratio, and, for claim 6, hot-melt extrusion. The patent’s ordinary 20-year term expired in 2020 based on its 1999 priority and 2000 nonprovisional filing chronology. It does not create an active United States exclusivity barrier today.

What does U.S. Patent 6,488,963 protect?

The patent protects a controlled-release dosage formulation with four central technical elements:

A therapeutic compound.
High-molecular-weight PEO with a molecular weight of approximately 1,000,000 to 10,000,000 Daltons.
A PEO-to-therapeutic-compound ratio ranging from approximately 99.99:0.01 to 50:50 by weight.
A non-film dosage architecture.

The claims are directed to a polymer matrix or comparable non-film dosage structure in which high-molecular-weight PEO controls drug release. The claims do not identify a particular active pharmaceutical ingredient, disease, dosage strength, tablet shape, release duration, or therapeutic indication.

Claim	Subject matter	Key limitation
1	Core formulation	Non-film formulation, therapeutic compound, PEO of about 1,000,000 to 10,000,000 Daltons, PEO:drug ratio of about 99.99:0.01 to 50:50
2	Claim 1 plus plasticizer	Plasticizer required
3	Claim 2 plus specified plasticizer classes	Includes oligomers, copolymers, oils, organic molecules, polyols, ester plasticizers, glycol ethers, polypropylene glycol, block polymers, and lower-MW PEO
4	Claim 3 plus low-MW PEO	Adds PEO below about 500,000 Daltons
5	Claim 4 plus PEG	Requires polyethylene glycol
6	Claim 1 plus manufacturing process	Formulation prepared by hot-melt extrusion

The patent therefore has a broad independent composition claim, dependent composition claims directed to plasticization, and one process-dependent claim.

How should claim 1 be construed?

Claim 1 is the principal infringement claim. A product generally would need to satisfy each limitation to fall within its literal scope.

Non-film controlled-release formulation

The claim excludes a film dosage form. The patent instead targets solid or matrix-based formulations, including tablets, extruded rods, pellets, granules, or other dosage forms that do not rely on a drug-containing film as the claimed controlled-release structure.

The phrase “non-film” is important. A product could contain a coating, lubricant, seal, or outer protective layer and still avoid the claim if the controlled-release formulation itself is not a film. The analysis would depend on whether the film is merely protective or performs the claimed release-control function.

High-molecular-weight PEO

The required PEO molecular weight is approximately 1,000,000 to 10,000,000 Daltons. The range is technically significant because very high-molecular-weight PEO produces high melt viscosity, swelling, gel formation, and erosion resistance.

A formulation using PEO below 1,000,000 Daltons as its only release-controlling PEO would be outside the literal molecular-weight limitation of claim 1. Claim 4 does not eliminate this requirement. It adds lower-molecular-weight PEO as an additional component to a claim 1 formulation.

The word “about” creates a boundary issue. A formulation with a nominal polymer molecular weight just below 1,000,000 or just above 10,000,000 could present a claim-construction dispute. Molecular-weight measurement method, supplier specification, batch variability, and whether the patent uses weight-average or another molecular-weight measure would be material.

PEO-to-drug ratio

The claim covers a PEO-to-therapeutic-compound weight ratio from approximately 99.99:0.01 to 50:50. This is a polymer-rich range.

PEO:drug ratio	Approximate PEO content relative to PEO plus drug	Claim position
99.99:0.01	99.99%	Within upper end
90:10	90%	Within range
75:25	75%	Within range
60:40	60%	Within range
50:50	50%	Within lower end
40:60	40%	Outside literal range

The claim language appears to calculate the ratio between PEO and therapeutic compound, not between all formulation ingredients. Excipients such as plasticizers, fillers, lubricants, binders, and stabilizers may therefore not change the claimed PEO-to-drug ratio unless the specification or prosecution history supports a different calculation.

The upper polymer content can be commercially important. A formulation containing 90% or more PEO relative to drug may be suitable for potent drugs but less attractive for high-dose active ingredients because of tablet size and manufacturing efficiency.

Therapeutic compound

The claim does not limit the therapeutic compound to a chemical class. It may cover small-molecule drugs, salts, solvates, polymorphs, and potentially other therapeutic substances, subject to the patent’s specification and the applicable claim-construction record.

The breadth creates potential written-description and enablement questions across a large universe of drugs. Those issues would normally be assessed from the specification, examples, prosecution history, and any validity challenge. The issued claim carries a statutory presumption of validity under 35 U.S.C. § 282.

What do claims 2 through 5 add?

Claims 2 through 5 narrow the formulation by adding plasticizer limitations.

Claim 2: any plasticizer

Claim 2 requires a plasticizer but does not initially limit the plasticizer to a defined chemical class. The plasticizer may reduce melt viscosity, improve processability, increase flexibility, modify hydration, or alter drug release.

Because claim 2 depends on claim 1, the formulation still must contain high-molecular-weight PEO within the approximately 1,000,000 to 10,000,000 Dalton range and remain within the claimed PEO-to-drug ratio.

Claim 3: broad plasticizer Markush group

Claim 3 lists multiple plasticizer categories:

Oligomers
Copolymers
Oils
Organic molecules
Polyols with aliphatic hydroxyl groups
Ester-type plasticizers
Glycol ethers
Poly(propylene glycol)
Multi-block polymers
Single-block polymers
PEO below approximately 500,000 Daltons

The list is technically broad and may overlap with conventional pharmaceutical excipients and processing aids. The term “organic molecule” is particularly expansive. Its practical scope would depend on claim construction and the specification’s examples.

A product using a plasticizer outside the listed categories might avoid literal infringement of claim 3 while remaining potentially within claim 2.

Claim 4: lower-molecular-weight PEO as an additional component

Claim 4 requires the formulation to contain PEO below approximately 500,000 Daltons. This limitation should be read together with claim 1’s requirement for high-molecular-weight PEO of approximately 1,000,000 to 10,000,000 Daltons.

Accordingly, claim 4 appears to require two PEO populations:

High-molecular-weight PEO within the claim 1 range.
Lower-molecular-weight PEO below approximately 500,000 Daltons.

The lower-molecular-weight PEO may function as a plasticizer or processing modifier. A formulation containing only low-molecular-weight PEO would not satisfy claim 4 because it would fail the inherited claim 1 limitation.

Claim 5: polyethylene glycol

Claim 5 adds PEG to the claim 4 formulation. PEG is chemically related to PEO but normally refers to lower-molecular-weight material. Claim 5 therefore covers a formulation containing high-molecular-weight PEO, lower-molecular-weight PEO, and PEG.

The distinction between PEG and PEO may depend on molecular weight, nomenclature, supplier specifications, and the patent’s disclosure. A product using PEG alone would not meet claim 5 because claim 5 depends on claims 1 through 4.

What does claim 6 protect?

Claim 6 covers the claim 1 formulation when prepared by hot-melt extrusion, or HME.

HME introduces a process limitation involving:

Heating the polymer and active ingredient.
Mixing or kneading the components in a molten or softened state.
Forming an extrudate or dosage precursor.
Producing the controlled-release formulation through the extrusion process.

Claim 6 is narrower than claim 1 because it requires a particular manufacturing method. It does not depend on claims 2 through 5. A product made by HME that uses a plasticizer may infringe claim 6 if it satisfies claim 1, but claim 6 itself does not require a plasticizer.

A conventional wet-granulated or direct-compression tablet could potentially fall within claim 1 but not claim 6. Conversely, HME alone is insufficient for claim 6 if the formulation does not contain the required high-molecular-weight PEO and PEO-to-drug ratio.

When did U.S. Patent 6,488,963 lose exclusivity?

The patent’s ordinary term expired in 2020.

Milestone	Date or status
Earliest priority chronology	1999
U.S. nonprovisional filing chronology	2000
Patent grant	December 3, 2002
Ordinary 20-year term	2020
Current status	Expired by term

For a United States utility patent filed after June 8, 1995, the basic term is generally 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and other statutory adjustments under 35 U.S.C. § 154.

No drug-specific patent term extension is apparent from the claims because the patent does not claim a particular approved drug or regulatory product. A regulatory patent-term extension under 35 U.S.C. § 156 would ordinarily require an eligible regulated product and qualifying regulatory review.

Because the patent expired, its claims no longer provide a current U.S. patent exclusion right. The claims remain relevant as prior art and as historical technology in freedom-to-operate analysis.

What is the Orange Book status of U.S. Patent 6,488,963?

U.S. Patent 6,488,963 is not, by itself, an Orange Book drug patent.

The FDA Orange Book lists patents submitted by new drug application, or NDA, holders for specific approved drug products. A broad platform patent that does not identify an NDA product, active ingredient, dosage form, or approved indication generally has no independent Orange Book listing. The patent therefore does not create a direct Paragraph IV pathway.

A generic applicant may still confront Orange Book-listed patents covering a particular drug’s formulation, method of use, or drug substance. Those patents would be evaluated separately from U.S. Patent 6,488,963 under the Hatch-Waxman framework.

Are there Paragraph IV challenges or biosimilar risks?

Paragraph IV risk

There is no inherent Paragraph IV challenge directed to U.S. Patent 6,488,963. Paragraph IV certifications apply when an ANDA applicant addresses an Orange Book-listed patent for the reference drug. This patent is a general formulation patent and is expired.

Any historical Paragraph IV dispute involving a product that used high-molecular-weight PEO would likely have concerned separate patents listed for that product, not this patent as a standalone platform patent.

Biosimilar risk

Biosimilar risk is not material. The claimed invention concerns a small-molecule-style pharmaceutical formulation and polymer processing method. It does not claim a biologic, biosimilar, antibody, cell therapy, recombinant protein, or biologic manufacturing process.

The relevant competitive risk is generic or follow-on formulation competition, not biosimilar substitution.

What patent landscape surrounds high-molecular-weight PEO controlled release?

The relevant patent landscape includes five technology groups.

Hydrophilic matrix patents

These patents cover drug release through polymer hydration, gel formation, diffusion, and matrix erosion. Common polymers include HPMC, hydroxypropyl cellulose, polyethylene oxide, carbomers, and related hydrophilic polymers.

PEO-specific formulation patents

These patents may claim:

Particular PEO molecular-weight combinations.
PEO with defined drug loading.
Specific ratios of polymer to active ingredient.
PEO combined with ionic polymers or hydrophobic excipients.
Abuse-deterrent or tamper-resistant dosage forms.
Specific release profiles or dissolution limits.

Hot-melt extrusion patents

HME patents may claim:

Extruder operating conditions.
Screw configuration.
Temperature and residence time.
Drug-polymer premixing.
Extruded dosage forms.
Continuous manufacturing.
Solvent-free processing.

Claim 6 is most exposed to this adjacent landscape because a commercial product may practice multiple HME patents even if U.S. Patent 6,488,963 has expired.

Film and coating patents

The “non-film” limitation separates this patent from film-based controlled-release systems. Other patents may cover polymeric films, coating layers, multilayer tablets, osmotic coatings, or drug-loaded oral films.

Drug-specific formulation patents

Commercial products often depend on later patents directed to a specific active ingredient, formulation, release profile, strength, indication, or dosage form. Those patents can remain enforceable after an older platform patent expires.

How strong was the patent estate?

The patent had meaningful breadth as a platform claim but limited present-day commercial strength because its term has expired.

Factor	Assessment
Chemical scope	Broad; therapeutic compound is not limited to a drug class
Polymer scope	Moderate; confined to high-MW PEO of approximately 1,000,000 to 10,000,000 Daltons
Ratio scope	Broad within a polymer-rich range
Dosage-form scope	Broad among non-film formulations
Process scope	Narrower in claim 6 because HME is required
Dependent claims	Add plasticizer and low-MW PEO or PEG limitations
Orange Book relevance	None as a standalone platform patent
Current enforceability	Expired
Generic entry effect	No current blocking effect from this patent
Manufacturing barrier	Historical only; current barriers would arise from later patents, know-how, or manufacturing capability

The strongest historical claim was claim 1 because it combined a broad therapeutic-compound definition with a broad non-film formulation structure. Claim 6 was narrower and easier to design around through a non-HME manufacturing process.

What design-around strategies avoid the claims?

Potential design-around routes include:

Use PEO below approximately 1,000,000 Daltons as the principal release-controlling polymer.
Use a polymer other than PEO, such as HPMC, HPC, carbomer, or a hydrophobic matrix former.
Use a PEO-to-drug ratio below approximately 50:50.
Use a film-based controlled-release system.
Manufacture the formulation without hot-melt extrusion to avoid claim 6.
Use a nonplasticized formulation to avoid claims 2 through 5.
Use a low-molecular-weight polymer system without the high-molecular-weight PEO required by claim 1.

These routes would have been relevant during the patent term. They remain useful for distinguishing the patent from later formulation patents and for reconstructing historical freedom-to-operate positions.

What litigation, licensing, and settlement issues affect the patent?

The claims do not identify a licensed product, approved drug, settlement, or commercial partner. The patent’s platform character means licensing would likely have been relevant to formulation technology, polymer processing, or university technology transfer rather than to a single branded drug.

Because the patent expired, any historical license would normally have little effect on current United States exclusion rights unless it contains surviving royalty, confidentiality, know-how, or field-of-use obligations. Those contractual issues are distinct from patent enforceability.

There is no current litigation pathway against a generic manufacturer based solely on this expired patent. Any present dispute would have to rely on a different unexpired patent, trade secret, contract, regulatory exclusivity right, or product-specific intellectual-property asset.

Key Takeaways

U.S. Patent 6,488,963 covers non-film controlled-release formulations using high-molecular-weight PEO.
Claim 1 requires PEO of approximately 1,000,000 to 10,000,000 Daltons and a PEO-to-drug ratio of approximately 99.99:0.01 to 50:50.
Claims 2 through 5 add plasticizer, lower-molecular-weight PEO, and PEG limitations.
Claim 6 covers hot-melt extrusion of the claim 1 formulation.
The patent is not a drug-specific Orange Book patent.
Paragraph IV and biosimilar risks are not created by this patent itself.
The ordinary patent term expired in 2020.
Current generic or formulation competition is not blocked by U.S. Patent 6,488,963.
Later patents covering specific drugs, release profiles, HME conditions, coatings, or formulations may remain commercially relevant.

FAQs About U.S. Patent 6,488,963

Does U.S. Patent 6,488,963 cover all polyethylene oxide controlled-release tablets?

No. It requires high-molecular-weight PEO of approximately 1,000,000 to 10,000,000 Daltons, a specified PEO-to-drug ratio, and a non-film formulation. Products using other polymers, lower-molecular-weight PEO alone, a different ratio, or a film architecture may fall outside claim 1.

Can a formulation infringe claim 1 without using hot-melt extrusion?

Yes. Hot-melt extrusion is required only by claim 6. Claim 1 is a composition claim and does not require a particular manufacturing process.

Does adding PEG avoid infringement of claim 1?

No. Adding PEG does not avoid claim 1 if the formulation still contains the required high-molecular-weight PEO and falls within the claimed ratio. PEG is relevant to dependent claim 5, not as an automatic exclusion from claim 1.

Is a formulation with 60% drug and 40% PEO within the claimed ratio?

On the stated ratio, no. A 40:60 PEO-to-drug ratio is below the claimed approximately 50:50 lower boundary. The result could change only if claim construction or the patent record supports a different method of calculating the ratio.

Does the expired patent still matter for new PEO formulation development?

Yes, as prior art and as a technical reference. It does not currently block practice of the expired claims, but later patents may cover specific active ingredients, dosage forms, release profiles, manufacturing conditions, or commercial formulations.

References

United States Patent No. 6,488,963. (2002). Controlled release formulations. United States Patent and Trademark Office.
United States Code, Title 35, § 154. (2024). Contents and term of patent; provisional rights.
United States Code, Title 35, § 156. (2024). Extension of patent term.
United States Code, Title 35, § 282. (2024). Presumption of validity; defenses.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.
U.S. Food and Drug Administration. (2024). Abbreviated new drug application submissions: Refuse-to-receive standards. Center for Drug Evaluation and Research.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	427124	⤷ Start Trial
Australia	3508097	⤷ Start Trial
Germany	09003265	⤷ Start Trial
Germany	69739343	⤷ Start Trial
Denmark	1014941	⤷ Start Trial
European Patent Office	1014941	⤷ Start Trial
European Patent Office	2065055	⤷ Start Trial
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Details for Patent: 6,488,963

Summary for Patent: 6,488,963