United States Patent 10,188,644: Claim Scope, Expiration Risk, and Oxycodone Microparticle Patent Landscape
U.S. Patent No. 10,188,644 protects a narrow controlled-release oxycodone formulation and its manufacturing process. The core technology uses oxycodone or oxycodone myristate, myristic acid, beeswax, and carnauba wax. The microparticles are produced from a homogeneous melt and subjected to a defined curing sequence involving temperatures above and below an approximately 36°C inversion temperature.
The patent is commercially relevant to oxycodone extended-release products, particularly Xtampza ER, an abuse-deterrent oxycodone product marketed by Collegium Pharmaceutical. Its strongest protection is directed to the combination of composition, thermal processing, and post-manufacture dissolution stability. Its principal vulnerabilities are claim ambiguity, the unusual temperature language, and the difficulty of proving process limitations from a finished commercial product.
What does U.S. Patent 10,188,644 protect?
The patent has four principal claim groups:
| Claim group |
Claims |
Subject matter |
| Composition and process |
1-16 |
Oxycodone microparticles made from a wax-and-fatty-acid melt and cured by a temperature sequence |
| Capsules |
17-20 |
Capsules containing the claimed microparticle compositions |
| Microparticle product |
21 |
Solid or formulated microparticles made from the claimed melt and curing process |
| Therapeutic use |
22-28 |
Treatment of pain with the compositions, microparticles, or capsules |
The independent claims are claims 1 and 21. Claim 1 is a pharmaceutical composition claim with process-defined product limitations. Claim 21 is directed more directly to the microparticle product.
The claim architecture combines:
- A specified active pharmaceutical ingredient.
- A specified lipid and wax matrix.
- Formation from a substantially homogeneous melt.
- Conversion of the melt into solid microparticles.
- A curing step lasting at least approximately 48 hours.
- A sequential temperature treatment involving a first temperature above the inversion temperature and a second temperature below it.
This combination is narrower than a generic oxycodone extended-release formulation claim. A competing product would generally need to satisfy every material limitation of an asserted claim to create literal infringement.
Which formulation ingredients are required by the patent?
Claim 1 requires one of two active-ingredient configurations:
- Oxycodone with myristic acid, beeswax, and carnauba wax; or
- Oxycodone in the form of a fatty acid salt with beeswax and carnauba wax.
Claim 21 expressly identifies oxycodone or oxycodone myristate, beeswax, carnauba wax, and sufficient myristic acid to produce substantially homogeneous microparticles.
The principal formulation limitations are:
| Component |
Claim limitation |
| Oxycodone |
Required, generally 9 mg to 72 mg in dependent claims |
| Oxycodone fatty-acid salt |
Permitted as an alternative to free oxycodone |
| Myristic acid |
30 wt.% to 70 wt.% in claim 10; 40 wt.% to 60 wt.% in claim 11 |
| Beeswax and carnauba wax |
Combined 20 wt.% to 60 wt.% in claim 12; 30 wt.% to 50 wt.% in claim 13 |
| Melt |
Must be substantially homogeneous |
| Microparticles |
Must be formed from the melt |
| Curing |
At least approximately 48 hours |
| Temperature profile |
First temperature above inversion temperature, followed by a second temperature below it |
Claims 14-16 create narrower composition combinations. Claim 16 is particularly important because it combines the narrower oxycodone dose range, the narrower myristic-acid range, and the narrower combined-wax range.
How does the curing process limit infringement?
The curing process is the central technical limitation.
The claims require the microparticles to be cured at one or more temperatures from 25°C up to the inversion temperature, while also requiring curing first above the inversion temperature and later below it. Claim 7 identifies the inversion temperature as approximately 36°C.
Read literally, this language creates an internal tension:
- Claims 1 and 21 describe curing within a range ending at the inversion temperature.
- The same claims require a first curing temperature above the inversion temperature.
- The first step therefore appears outside the stated 25°C-to-inversion-temperature range.
This issue could affect claim construction, prosecution-history analysis, and validity. A court may construe the language to mean that the overall curing protocol includes a high-temperature step followed by a low-temperature curing step. The court could also treat the phrase as an inconsistency requiring resolution through the specification and prosecution history.
A competitor using the same ingredients but curing only below 36°C could have a non-infringement position if the high-temperature step is a mandatory limitation. Conversely, a competitor using a high-temperature step but no subsequent low-temperature cure could argue that the sequential limitation is absent.
What dissolution performance is protected?
Claims 2-6 add stability-based dissolution limitations. The product must show less change in dissolution after six months at 25°C and 60% relative humidity than otherwise identical uncured microparticles.
The dependent claims create progressively narrower performance thresholds:
| Claim |
Maximum change in mean drug release at four hours |
| 3 |
Less than 15% |
| 4 |
Less than 10% |
| 5 |
Less than 5% |
| 6 |
Less than 2.5% |
The test conditions include:
- USP Apparatus I
- 100 RPM where specified
- 900 mL dissolution medium where specified
- pH 4.5 sodium acetate buffer
- 0.03% Tween 20
- 37°C
- Six months at 25°C and 60% relative humidity
These claims offer potentially strong differentiation if the patent owner has reproducible comparative stability data. They also create litigation risk because the claims depend on testing methodology and comparison against uncured material.
The claims do not fully specify several potentially material variables, including:
- The initial and final dissolution values used to calculate change.
- Whether change means absolute percentage points or relative percentage change.
- The number of units tested.
- Acceptance criteria for variability.
- The precise composition of the “otherwise identical” uncured comparator.
- Whether the claim requires testing of commercial batches or laboratory batches.
Those omissions could create disputes over indefiniteness, enablement, or whether a defendant's product satisfies the claimed performance result.
How strong is the composition patent estate?
The estate is technically narrow but commercially meaningful.
Strengths
The claims combine multiple limitations that are difficult to assess from a label alone:
- Exact or closely related wax ingredients.
- Myristic acid or oxycodone myristate.
- Melt-based microparticle manufacture.
- A defined curing duration.
- A two-stage thermal sequence.
- In some claims, measurable dissolution stability.
A competitor may avoid literal infringement by changing any one of the following:
- Replacing myristic acid.
- Replacing beeswax or carnauba wax.
- Using a non-melt manufacturing process.
- Forming particles by spray drying, granulation, coating, or solvent evaporation.
- Omitting the above-inversion-temperature curing step.
- Using a different curing sequence.
- Using a different oxycodone salt.
- Altering the composition outside the claimed percentage ranges.
Weaknesses
The patent has several potential pressure points:
- The temperature language is internally difficult to reconcile.
- “Approximately 36°C” may create a boundary dispute over the inversion temperature.
- The relative dissolution limitations require a comparator and a defined testing protocol.
- Weight percentages may be disputed if the claim does not clearly identify whether they are based on the total composition, microparticles, or active-containing matrix.
- Product-by-process proof may be difficult if the finished microparticles do not retain an analytically identifiable signature of the manufacturing sequence.
- The claims do not cover every oxycodone extended-release formulation or every abuse-deterrent platform.
The strongest claims for enforcement are likely claims 14-16 and 18-20 if the accused product matches the listed dose and excipient ranges. The broadest commercial claim is claim 1, but it is also exposed to disputes concerning the thermal sequence.
What patent protects Xtampza ER?
Xtampza ER is an extended-release oxycodone product approved by the FDA under NDA 208090. The FDA labeling describes the product as an abuse-deterrent formulation using DETERx technology and identifies a portfolio of patents covering the product and related formulation technology (FDA, 2023).
Public FDA labeling has identified multiple U.S. patents associated with Xtampza ER, including:
| Patent |
General relevance |
| 8,486,972 |
Earlier oxycodone controlled-release and abuse-deterrent formulation technology |
| 8,808,726 |
Related controlled-release formulation claims |
| 9,072,742 |
Additional product and formulation protection |
| 9,649,283 |
Later continuation or related formulation coverage |
| 10,188,644 |
Cured oxycodone microparticle compositions and processes |
| 10,292,925 |
Related formulation or manufacturing coverage |
| 10,813,873 |
Later portfolio patent |
| 11,147,782 |
Later continuation or related product coverage |
| 11,234,918 |
Later portfolio protection |
The exact Orange Book listing and active status should be evaluated patent by patent because listing status can change through delisting, expiration, corrections, pediatric extensions, or regulatory updates. An Orange Book listing also does not establish that every claim in a patent reads on every strength or presentation of the approved product.
When does U.S. Patent 10,188,644 expire?
The patent grant date was January 29, 2019. The expiration date cannot be determined from the claims or grant number alone. It depends on the earliest effective nonprovisional priority date, patent-term adjustment, terminal disclaimers, and any applicable patent-term extension.
For commercial diligence, the relevant date is the adjusted expiration date shown in the USPTO Patent Center record and any applicable Orange Book entry. A continuation patent generally receives the term of the earliest claimed priority application, subject to statutory adjustments under 35 U.S.C. §§ 154 and 156.
The patent should therefore be treated as potentially extending into the early 2030s unless the official term calculation shows an earlier terminal date. The exact enforceable term requires the USPTO transaction history and terminal-disclaimer record.
What is the Orange Book status of the patent?
The patent is associated with the Xtampza ER product portfolio and is relevant to FDA-listed product protection. The Orange Book framework allows an NDA holder to list patents claiming:
- The approved drug substance.
- The approved drug product.
- A method of using the approved drug.
Patent 10,188,644 is most naturally characterized as a drug-product and formulation patent. Its claims cover the composition, microparticles, capsule dosage form, and treatment method rather than oxycodone as a new chemical entity.
An ANDA applicant seeking approval for a product that could be covered by the listed patent may need to submit one of four patent certifications:
- Paragraph I: no patent information is listed.
- Paragraph II: the listed patent has expired.
- Paragraph III: the applicant will wait until expiration.
- Paragraph IV: the patent is invalid, unenforceable, or will not be infringed.
Which companies are challenging the patent?
The supplied claim set does not identify a Paragraph IV notice, ANDA applicant, district-court complaint, settlement, or appellate decision directed specifically to U.S. Patent 10,188,644.
A current challenge assessment requires matching FDA ANDA activity with patent litigation records. The absence of an identified challenge in the supplied materials means that no named generic challenger or settlement should be attributed to this patent.
The principal potential challengers would be manufacturers pursuing generic oxycodone extended-release capsules, including firms with experience in controlled-release opioids. A Paragraph IV dispute would likely focus on:
- Whether the generic contains the claimed wax and myristic-acid combination.
- Whether its particles are prepared from a homogeneous melt.
- Whether it undergoes the claimed high-then-low temperature curing sequence.
- Whether the process limitations can be proven in the finished product.
- Whether the claims are indefinite or lack written-description support.
What generic launch risks exist?
Generic entry scenarios depend on both regulatory approval and patent litigation timing.
| Launch scenario |
Commercial effect |
| No ANDA challenge |
Entry is delayed until relevant patent and exclusivity barriers expire |
| Paragraph III certification |
Applicant accepts delayed launch until the listed patent term ends |
| Paragraph IV certification with no suit |
FDA approval may proceed after statutory review periods |
| Paragraph IV certification followed by timely suit |
Approval may be subject to a 30-month stay under Hatch-Waxman |
| Successful invalidity or non-infringement case |
Earlier generic entry becomes possible |
| Settlement with a permitted entry date |
Entry occurs on the negotiated date, subject to regulatory approval |
Xtampza ER is a small-molecule product. Biosimilar risk does not apply. Competitive risk comes from ANDA products, authorized generics, alternative extended-release oxycodone products, and non-oxycodone opioid formulations.
How does this patent compare with broader oxycodone patents?
Patent 10,188,644 is narrower than patents claiming oxycodone as an active ingredient or broadly claiming extended-release opioid dosage forms. It is stronger when the accused product uses the same DETERx-type microparticle architecture and weaker when the competitor uses a different release platform.
| Patent category |
Scope |
Relevance to Patent 10,188,644 |
| Oxycodone compound patent |
Active ingredient |
Usually expired or commercially weak for modern products |
| Broad controlled-release opioid patent |
Release mechanism or dosage form |
May cover competing platforms |
| Abuse-deterrent formulation patent |
Tamper resistance and physical properties |
Overlaps commercially but not necessarily literally |
| Wax-matrix microparticle patent |
Specific excipient and particle system |
Closest technical category |
| Manufacturing-process patent |
Melt formation, curing, particle production |
Critical to claims 1 and 21 |
| Method-of-use patent |
Treatment of pain |
Relevant to claims 22-28 but generally easier to design around |
What manufacturing and intellectual-property barriers remain?
The patent creates a barrier where a manufacturer must reproduce the commercial performance of the reference product while avoiding the claimed formulation and curing sequence.
The principal technical barriers are:
- Achieving controlled oxycodone release without the claimed wax system.
- Maintaining dissolution stability after storage.
- Demonstrating abuse-deterrent properties.
- Scaling a microparticle melt process without batch variability.
- Controlling particle size and drug distribution.
- Establishing bioequivalence through an ANDA.
- Producing sufficient evidence to support a paragraph IV non-infringement position.
A non-infringing alternative could use a different fatty acid, polymeric matrix, coating process, hot-melt extrusion system, or particle-formation technique. The commercial substitute must still satisfy FDA bioequivalence and quality requirements.
Key Takeaways
- U.S. Patent 10,188,644 covers cured oxycodone microparticles made from a myristic-acid and wax melt.
- The claims require oxycodone or an oxycodone fatty-acid salt, beeswax, carnauba wax, melt formation, microparticle formation, and a curing protocol.
- Claim 7 places the inversion temperature at approximately 36°C.
- Claims 1 and 21 contain potentially material tension between curing up to the inversion temperature and requiring a first step above it.
- Claims 3-6 add dissolution-stability performance thresholds ranging from less than 15% to less than 2.5% change.
- Claims 17-20 extend protection to capsules, while claims 22-28 cover treatment of pain.
- The patent is relevant to the Xtampza ER patent portfolio and has greater commercial importance as a product and process patent than as a broad oxycodone patent.
- Biosimilar competition is irrelevant because oxycodone is a small molecule.
- Generic risk will turn on ANDA certifications, patent listings, litigation, and the ability to design around the wax, myristic-acid, and thermal-curing limitations.
- The exact expiration date requires the USPTO term calculation, including priority, patent-term adjustment, and any terminal disclaimer.
FAQs
Does Patent 10,188,644 cover all extended-release oxycodone products?
No. It is limited to formulations and microparticles containing specified ingredients and made using specified melt and curing conditions.
Can a generic avoid the patent by removing myristic acid?
Potentially. Removing myristic acid may avoid literal infringement of claims requiring myristic acid, but the product must still satisfy FDA bioequivalence and may face other patents in the Xtampza ER portfolio.
Is oxycodone myristate expressly covered?
Yes. Claim 21 expressly identifies oxycodone or a myristate salt of oxycodone. Other claims refer more generally to a fatty-acid salt of oxycodone.
Does the patent claim abuse deterrence by itself?
Not expressly. The claims focus on microparticle composition, manufacturing, curing, dissolution stability, capsules, and pain treatment. Abuse-deterrent characteristics may be commercially relevant without being an independent claim limitation.
Would a different curing temperature avoid infringement?
Possibly, but the answer depends on the complete temperature history. A product using a different sequence may avoid the literal requirement of curing first above and then below the inversion temperature, subject to claim construction and the doctrine of equivalents.
References
-
U.S. Patent No. 10,188,644. (2019). Pharmaceutical compositions comprising cured microparticles. United States Patent and Trademark Office.
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U.S. Food and Drug Administration. (2023). Xtampza ER prescribing information. NDA 208090.
-
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Orange Book.
-
U.S. Patent and Trademark Office. (2024). Patent term adjustment and patent term extension information. https://www.uspto.gov
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Federal Food, Drug, and Cosmetic Act, 21 U.S.C. § 355.
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Patent Act, 35 U.S.C. §§ 154, 156.
