Scope, Claims and US Patent Landscape for US Patent 8,846,090 (Oxycodone/Naloxone Oral Formulation With Ethylcellulose-Fatty Alcohol Diffusion Matrix)

US 8,846,090 claims an oral oxycodone (opioid agonist)/naloxone (opioid antagonist) fixed-dose formulation where both actives are embedded in a specific diffusion-controlled matrix built from ethylcellulose plus a fatty alcohol at 5-30% by weight. The claims tightly define (i) actives (oxycodone salt forms; naloxone salt forms), (ii) matrix composition (ethylcellulose and fatty alcohol species and loading), (iii) dosing ranges and actuator ratios (oxycodone:naloxone by weight), and (iv) release behavior language that is framed as “sustained, invariant, and independent” release governed by ethylcellulose and the fatty alcohol and not by certain other polymer technologies (e.g., polymethacrylate and “relevant amount” hydroxyalkylcellulose).

What is the protected product shape in plain terms?

A tablet (or oral formulation) that:

contains oxycodone + naloxone together,
uses a diffusion matrix containing ethylcellulose + a fatty alcohol,
uses specific weight fractions:
- fatty alcohol: 5-30% of total formulation (independent claim 1)
- ethylcellulose: 1-15% of total formulation (claim set 26 and dependent sub-range claims)
uses specific species for the fatty alcohol (dependent claims list a set and also single out stearyl alcohol)
targets a defined independent release relationship for both actives, stated as “sustained, invariant, and independent release” and attributed to ethylcellulose and fatty alcohol
avoids some other matrix families:
- “not based on a polymethacrylate” (claim 23)
- “does not comprise a relevant amount of a hydroxyalkylcellulose” (claim 24)

What exactly do the independent claims cover?

Independent Claim 1 (core breadth)

Claim 1 defines the broadest combination set:

Oral formulation comprising:

Opioid agonist: at least one of oxycodone and pharmaceutically acceptable salts
Opioid antagonist: at least one of naloxone and pharmaceutically acceptable salts
Diffusion matrix containing both actives and comprising:
- ethylcellulose
- at least one fatty alcohol
Matrix performance:
- configured to provide “sustained, invariant, and independent release” of opioid agonist and antagonist
Fatty alcohol loading:
- 5-30% by weight of total formulation

This is a relatively compact claim structure: it does not restrict tablet hardness, geometry, particle size, or the identity of excipients beyond the required matrix components and a few exclusions in dependent claims.

Independent Claim 26 (matrix composition focus)

Claim 26 repeats the formulation concept and limits the matrix composition in a specific way:

Same actives: oxycodone salts + naloxone salts
Same diffusion matrix: ethylcellulose + fatty alcohol
Same release language: “sustained, invariant, and independent release”
Explicit matrix loading:
- ethylcellulose present in 1-15% by weight of total formulation

Claim 26 is narrower than Claim 1 only in that it expressly constrains ethylcellulose, while Claim 1 expressly constrains fatty alcohol (5-30%). In practice, the two independent claims are complementary: the claim set overall pins both ethylcellulose and fatty alcohol within the recited regimes via dependent claims.

Which dependent claims provide the practical “design space” boundaries?

Below are the main dependent constraints that control formulation freedom and define likely infringement risk for close substitutes.

Fatty alcohol identity and loading

Fatty alcohol species (Claims 2, 27, 28):

lauryl alcohol
myristyl alcohol
stearyl alcohol
cetylstearyl alcohol
ceryl alcohol
cetyl alcohol

Stearyl alcohol singled out (Claims 3, 28):

“fatty alcohol is stearyl alcohol”

Fatty alcohol loading (Claims 18-19, plus general in Claim 1):

Claim 18: 15-20%
Claim 19: 10-25%
Claim 1 base: 5-30% (not limited to stearyl alcohol)

Ethylcellulose loading (Claims 16, 17, 41, 42)

Claim 16: ethylcellulose 1-15%
Claim 17: ethylcellulose 5-9%
Claim 41: ethylcellulose 3-12%
Claim 42: ethylcellulose 5-9% (overlap, redundant reinforcement in narrower window)

These ranges matter because they tie the release behavior language (“sustained, invariant, and independent”) to a specific hydrophobic matrix-former level.

Oxycodone and naloxone dose ranges

Oxycodone (mg) (multiple dependent claims):

Claim 5: 5-50 mg
Claim 11: 5-50 mg
Claim 9/34: 10-150 mg
Claim 10/35: 10-80 mg

Naloxone (mg) (multiple dependent claims):

Claim 7: 1-40 mg
Claim 32: 1-40 mg
Claim 9/34: 1-50 mg

Common pairing constraint (Claims 8, 33):

oxycodone HCl + naloxone HCl

Oxycodone:naloxone weight ratio (pharmacologically loaded control variable)

Multiple ratio claims define weight ratio boundaries:

Claim 12: 25:1 to 1:1
Claim 13: 5:1 to 1:1
Claim 14: exactly 5:1, 4:1, 3:1, 2:1, or 1:1
Claim 15: exactly 2:1
Claim 37-40 repeat the same ratio structure under Claim 26’s ethylcellulose framework
Claim 20/45 fix the ratio at 2:1 while also specifying stearyl alcohol and oxycodone and/or mg constraints

In practical competitive scenarios, this is one of the biggest levers. If a competitor changes the ratio out of the claimed windows, the formulation can avoid a broad swath of claim coverage.

What product forms and technology exclusions are built into the claim set?

Form factor

Claim 22: formulation is in the form of a tablet
Claim 47: same concept under Claim 26

Even if the primary invention is a tablet, the independent claim language already says “oral pharmaceutical formulation,” so “tablet” is a strengthening dependent claim for enforceability but not strictly required for infringement of the independent claims.

Technology exclusions

The claim set includes explicit limitations meant to differentiate from other controlled-release polymer systems:

Claim 23: matrix “not based on a polymethacrylate”
Claim 24: matrix does not comprise a relevant amount of a hydroxyalkylcellulose
Claims 25 and 50: sustained/invariant/independent release characteristics are determined by ethylcellulose and fatty alcohol

These provisions are important in freedom-to-operate (FTO) analysis because they target common industry substitution paths:

polymethacrylate-coated or methacrylate-based sustained release systems
hydroxyalkylcellulose-based gel matrices

Where is the claim “tightness” high, and where is it loose?

High tightness (fewer viable design-arounds)

These elements narrow the protected set significantly:

Must include ethylcellulose + a fatty alcohol in the diffusion matrix (independent claims)
Must meet specific wt% ranges:
- fatty alcohol: 5-30% (Claim 1)
- ethylcellulose: 1-15% (Claim 26)
Fatty alcohol must be one of the listed species in relevant dependent claims
The release behavior is constrained by claim language tying “invariant and independent release” to ethylcellulose + fatty alcohol
Oxycodone/naloxone dosing and ratio ranges are explicitly claimed in multiple dependent claims
Exclusions from polymethacrylate and “relevant amount” hydroxyalkylcellulose

Lower tightness (more room for excipients and processing variables)

These aspects are not comprehensively claimed:

No specific requirement for tablet shape, dimensions, or coating layers beyond being oral
No explicit particle size, process steps, or granulation method in the claim text you provided
No explicit exclusion of other excipients (e.g., fillers, binders, disintegrants), except the negative polymer-type exclusions in Claims 23 and 24

How broad is “independent release” in claim scope?

The claims use functional language:

“matrix is configured to provide sustained, invariant, and independent release of the opioid agonist and the opioid antagonist”
“sustained, invariant, and independent release characteristics … are determined by the ethylcellulose and the at least one fatty alcohol” (Claims 25 and 50)

From a patent landscape perspective, this phrasing is a double-edged sword:

It strengthens the invention narrative around a specific mechanism (ethylcellulose + fatty alcohol determine the release relationship).
It also gives claim scope leverage to capture formulations where competitors replicate the same functional release profile even if excipient selection differs, as long as the required matrix composition elements are present.

Competitive “at-risk” formulations mapped to claim elements

The table below shows which design choices are most likely to stay within the claimed envelope.

Design variable	Claim anchor(s)	At-risk zone
Actives	Claims 1, 26	Oxycodone (salts) + naloxone (salts) together in one oral formulation
Matrix polymer system	Claims 1, 26	Diffusion matrix with ethylcellulose + fatty alcohol
Fatty alcohol loading	Claim 1	5-30% by weight
Ethylcellulose loading	Claim 26	1-15% by weight (plus dependent sub-ranges)
Fatty alcohol identity	Claims 2-3, 27-28	Listed fatty alcohols; stearyl alcohol called out
Ratio	Claims 12-15, 37-40	25:1 to 1:1; with multiple dependent claims centered on 2:1
Dosing amounts	Claims 5, 7, 9-10, 34-35, 30-32	Multiple mg windows (5-50 mg oxycodone; 1-40 mg naloxone; up to 150 mg oxycodone depending on sub-claim)
Technology exclusions	Claims 23-24	Avoid polymethacrylate-based matrices; avoid “relevant amount” hydroxyalkylcellulose
Release mechanism attribution	Claims 25, 50	Release profile determined by ethylcellulose + fatty alcohol

Patent landscape: what other filings typically collide with this kind of claim set?

US 8,846,090’s claim architecture suggests a landscape with three collision zones:

1) Formulation patents around “oxy/ nalo” abuse deterrent fixed-dose products

This patent occupies a matrix-based controlled release space for oxycodone/naloxone with:

a defined diffusion matrix composition (ethylcellulose + fatty alcohol)
functional release behavior (“independent”)

In the market, multiple generations of abuse-deterrent oxycodone/naloxone formulations exist using different polymers and release strategies. The key competitive differentiators are:

polymer type (ethylcellulose vs other hydrophobic polymers)
whether fatty alcohol is present at 5-30% by weight
whether hydroxyalkylcellulose is present meaningfully
ratio (2:1 and other windows)

2) Controlled-release matrix patents using alternative polymers

The claim explicitly excludes:

polymethacrylates (Claim 23)
hydroxyalkylcellulose at relevant levels (Claim 24)

So the most likely direct design-around candidates are:

methacrylate-based diffusion or erosion systems
hydroxyalkylcellulose gel matrices
multi-polymer systems where ethylcellulose and the fatty alcohol combination is not present in the claimed proportional ranges

3) Mechanism-labeled diffusion matrix patents

Because claims use functional language tied to specific components, the landscape will also include:

patents claiming diffusion-controlled systems where release depends on a hydrophobic polymer and a lipid-like additive
patents describing “independent” release behavior for multiple drugs in the same matrix

In infringement analysis, you typically evaluate:

whether the competitor’s matrix includes both ethylcellulose and a fatty alcohol within the required wt% regimes
whether the release behavior for each drug is “independent” in the claimed sense (functional determination)
whether any technology exclusions are violated (polymethacrylate/hydroxyalkylcellulose)

Where the claim set is vulnerable to design-arounds (and where it is not)

Most viable design-arounds (based on the claim text provided)

Remove ethylcellulose from the diffusion matrix.
Remove fatty alcohol or reduce it below 5% by weight (Claim 1).
Use a diffusion matrix that is “based on polymethacrylate” or that includes “relevant amount” hydroxyalkylcellulose is likely to still be outside the claim due to explicit exclusions, though it could create other infringement risk with different patents.
Shift oxycodone:naloxone weight ratio outside broad windows (e.g., outside 25:1 to 1:1 or outside the narrower 5:1 to 1:1 and the common 2:1 dependent claims).

Less viable design-arounds

Changing only the fatty alcohol species while staying within the listed fatty alcohols.
Changing dosing quantities while staying within one of the dependent mg windows.
Maintaining ethylcellulose and fatty alcohol at the claimed weight fractions will usually keep the formulation inside the core claim theory even if other excipients differ.

Key Takeaways

US 8,846,090 covers oral oxycodone/naloxone formulations using a diffusion matrix of ethylcellulose + a fatty alcohol, with fatty alcohol at 5-30% (Claim 1) and ethylcellulose at 1-15% (Claim 26).
The claim set is tightened by explicit fatty alcohol species, mg dosing windows, and oxycodone:naloxone weight ratio constraints, with multiple dependent claims focusing on 2:1.
It includes functional release limitations requiring “sustained, invariant, and independent release” attributed to the ethylcellulose and fatty alcohol.
It includes technology exclusions: the matrix is not based on polymethacrylate and does not include a relevant amount of hydroxyalkylcellulose.
In landscape terms, infringement risk is highest for competitors that keep the same core polymer-lipid diffusion matrix at the claimed loadings and ratio regimes, even if excipient choices and process steps differ.

FAQs

1) What is the core novelty captured by the claims of US 8,846,090?

A controlled oral formulation where oxycodone and naloxone are released in a sustained, invariant, and independent manner using a diffusion matrix composed of ethylcellulose and a fatty alcohol at defined weight percentages.

2) Which components are mandatory in the independent claims?

Oxycodone (or salt) and naloxone (or salt), plus a diffusion matrix containing ethylcellulose and at least one fatty alcohol. The independent claims also impose key wt% constraints on fatty alcohol (Claim 1) and ethylcellulose (Claim 26).

3) Do dependent claims meaningfully narrow the fatty alcohol options?

Yes. Dependent claims list specific fatty alcohols (including stearyl alcohol) and impose additional fatty alcohol wt% ranges (including 10-25% and 15-20%).

4) Does the patent require a specific oxycodone:naloxone weight ratio?

Not in the independent claims as written, but multiple dependent claims require ratios such as 25:1 to 1:1, 5:1 to 1:1, and specifically enumerated options including 2:1.

5) What claim exclusions can guide design-arounds?

The matrix is not based on polymethacrylate (Claim 23) and does not comprise a relevant amount of hydroxyalkylcellulose (Claim 24).

References

[1] US Patent 8,846,090, “Oral pharmaceutical formulation comprising opioid agonist and opioid antagonist and diffusion matrix comprising ethylcellulose and fatty alcohol,” claims as provided in the prompt.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Germany	102 15 067	Apr 5, 2002
Germany	102 15 131	Apr 5, 2002

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
African Regional IP Organization (ARIPO)	2043	⤷ Start Trial
African Regional IP Organization (ARIPO)	2397	⤷ Start Trial
Argentina	039378	⤷ Start Trial
Argentina	039379	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,846,090

Summary for Patent: 8,846,090