United States Patent 11,154,521: Scope, Claims, and Patent Landscape for Oral Sodium Phenylbutyrate Taste-Masked Layered Particles
What is the core claim scope of US 11,154,521?
US 11,154,521 is directed to an oral pharmaceutical composition built from layered particles containing:
1) a seed core
2) a drug layer comprising sodium phenylbutyrate (SPB)
3) a taste-mask coating comprising a specific polymer: polymer formed from dimethylaminoethyl methacrylate, butyl methacrylate, and methyl methacrylate
The claims tighten the structure through quantitative composition ranges and particle-size constraints. Claim 1 functions as the independent “platform” claim; subsequent claims narrow into specific materials (seed excipients, binder/plasticizer grades), coating add-ons (talc, seal coating), performance (dissolution, plasma exposure), and dosage form (unit dose; powder/granules).
Claim 1 (Independent): What does it require, in exact terms?
Claim 1 requires all of the following:
A. Particle architecture
- A pharmaceutical composition for oral administration of sodium phenylbutyrate
- Comprising a plurality of layered particles
- Each layered particle includes:
- (i) seed core
- (ii) drug layer comprising sodium phenylbutyrate
- (iii) taste-mask coating comprising the defined polymer
B. Particle size distribution constraint
- A volume-based particle size distribution where:
- at least 90% of layered particles are < 500 μm
(Claim 21 narrows this further to < 400 μm for at least 90%.)
C. Composition by weight (global formulation ranges)
- Seed core: about 10% to 20% of total weight
- Sodium phenylbutyrate: greater than 60% of total weight
- Taste-mask coating: about 5% to 25% of total weight
D. Polymer identity constraint
- Taste-mask coating polymer is “a polymer formed from” three monomer-derived components:
- dimethylaminoethyl methacrylate
- butyl methacrylate
- methyl methacrylate
This monomer-definition is a key scope limiter. It is not written as “a polymer selected from” a list; it is written as a polymer “formed from” those three monomers.
How do the dependent claims narrow or expand scope?
Below is a structured map from Claim 1 into enforceable sub-scopes.
Which dependent claims define the coating/binders/plasticizers?
Taste-mask coating magnitude and polymer class
- Claim 2: taste-mask coating is about 5% to 10% of total weight.
- Claim 17: taste-mask coating polymer range is reiterated in the full composition: about 5% to 10% of the defined polymer.
Drug layer excipients
- Claim 4: drug layer comprises SPB + binder + plasticizer.
- Claim 5: binder is hydroxypropyl methylcellulose (HPMC).
- Claim 6: plasticizer is polyethylene glycol (PEG) MW 5,000 to 7,000.
- Claim 7: detailed drug layer composition:
- SPB ~65%
- HPMC 5% to 7%
- PEG (5,000 to 7,000) 0.1% to 1%
Seal coating between drug layer and taste-mask coating
- Claim 14: further comprises a seal coating between drug layer and taste-mask coating.
- Claim 15: seal coating about 1% to 5% by total weight.
- Claim 16: seal coating comprises a water-soluble polymer.
Talc and additional coating components
- Claim 8: taste-mask coating further comprises plasticizer and talc.
- Claim 9: plasticizer in the coating is PEG (MW 5,000 to 7,000).
- Claim 13: talc is < 4% by total weight of composition.
Seed core identity
- Claim 10: seed core comprises microcrystalline cellulose (MCC).
How do the dependent claims define overall formulation ranges?
The strongest “quantitative envelope” is Claim 17, which reads like a consolidated preferred embodiment:
Claim 17 full composition lock-in
- SPB: about 65% by total weight
- HPMC: 8% to 10% by total weight
- PEG (5,000 to 7,000): 0.5% to 3% by total weight
- MCC in seed core: 10% to 20% by total weight
- Talc in taste-mask coating: < 4% by total weight
- Defined taste-mask polymer: 5% to 10% by total weight
This is the tightest combination constraint in the set. It narrows both material identity (HPMC, MCC, PEG, talc) and numeric loading.
Additional broad ranges that align with the composition:
- Claim 11: composition further comprises about 8% to 10% HPMC
- Claim 12: further comprises about 0.5% to 3% PEG (5,000 to 7,000)
What performance-based claims materially change scope?
These claims link formulation identity to in vivo and in vitro outcomes. They can be important in both infringement and validity challenges, because they introduce technical criteria.
Bioequivalence / comparative bioavailability
- Claim 20: upon administration, composition is bioequivalent to an SPB formulation without a taste-mask coating.
This frames a regulatory-type standard into a claim outcome.
Taste test comparison
- Claim 23: scores favorably in a taste test compared to an SPB formulation without a taste-mask coating.
This is a comparative performance metric.
Plasma exposure timing
- Claim 24: upon administration, has greater SPB levels in plasma at 30 minutes compared to a modified release SPB formulation.
This targets early exposure versus modified-release comparators.
Dissolution behavior under pH/time
Two constraints appear to bracket release across pH:
- Claim 25: less than 15% SPB dissolves in neutral pH over 10 minutes
- Claim 26: at least 95% SPB dissolves at an acidic pH over 60 minutes
Taken together, the claims aim for “minimized neutral pH dissolution” and “robust acidic dissolution.”
What formulation forms are claimed?
- Claim 22: formulated in unit dosage form
- Claim 27: composition is a powder or granules
These restrict physical form and support oral solid dosage manufacture.
Does the claim set include a glidant option?
Yes:
- Claim 18: composition further comprises a glidant
- Claim 19: glidant is silica
This is a standard oral solid excipient option, but it can matter for process and formulation equivalence.
How broad is the independent claim in practice?
Claim 1 is broad in one dimension and narrow in another.
Broad elements
- “Plurality of layered particles” is not restricted to a specific manufacturing technique (no method steps in the text you provided).
- Seed core is not limited to MCC in Claim 1; MCC appears in Claim 10.
- Drug layer excipients beyond SPB are not required in Claim 1 (binder/plasticizer are required only in Claim 4).
- Performance assertions (bioequivalence, taste score, dissolution timing) are dependent, not required for Claim 1.
Narrow elements
- The taste-mask coating must contain the polymer “formed from” three specified monomers (dimethylaminoethyl methacrylate, butyl methacrylate, methyl methacrylate).
- Particle size distribution is constrained to at least 90% < 500 μm (or < 400 μm under Claim 21).
- Global composition ranges in Claim 1 are strict:
- Seed core 10% to 20%
- SPB > 60%
- Taste-mask coating 5% to 25%
Net: Claim 1 covers a formulation class defined by layered structure + specific polymer + particle size + mass balance ranges.
What is the enforceable “infringement map” for Claim 1?
For a competitor’s oral SPB product to fall within Claim 1, it must satisfy every required element:
Element-by-element checklist
1) Oral SPB composition
2) Comprised of layered particles (seed core + drug layer + taste-mask coating)
3) Taste-mask coating polymer is the one “formed from” dimethylaminoethyl methacrylate, butyl methacrylate, methyl methacrylate
4) Volume-based particle size distribution: ≥90% layered particles <500 μm
5) Mass fractions meet:
- seed core ~10% to 20%
- SPB >60%
- taste-mask coating ~5% to 25%
If any one element is missing, a strict literal infringement argument for Claim 1 fails based on claim construction principles.
Where are the likely design-arounds?
The claims provide clear “attack surfaces” for competitors trying to avoid literal scope.
Potential design-around levers
- Polymer identity: using a different taste-mask polymer not formed from the specified three monomers.
- Particle size distribution: shifting the particle distribution such that fewer than 90% of layered particles fall below 500 μm (or 400 μm for the narrower dependent claim).
- Mass balance: adjusting seed core %, coating % to fall outside the Claim 1 ranges.
- Layer architecture: changing from layered particles into an alternative morphology (e.g., matrix tablets, coacervates, different granule designs) so the product cannot be characterized as “layered particles” with the required strata.
- Excipient-specific dependent claims: using non-HPMC binders or non-PEG 5,000 to 7,000 plasticizers if one targets avoidance of dependent claims (though Claim 1 can still be implicated if those excipient constraints are not required for the independent claim).
How does the patent landscape typically position this kind of claim?
Even without additional documents in the record here, the claim language indicates a well-defined niche where patents cluster around:
- taste-masking strategies for SPB
- pH-responsive coatings
- granular or layered particulate delivery
- dissolution and early-release profiles for oral administration
This patent’s claim set is engineered to distinguish from:
- simple taste-masked coatings that do not use this monomer-defined polymer
- formulations that do not meet the explicit particle size distribution thresholds
- products optimized for release but not taste suppression under neutral pH
Key competitor vectors suggested by the claim set
A practical landscape review for infringement risk typically focuses on products claiming:
- SPB taste masking with polymers (especially methacrylate-based, Eudragit-like families)
- controlled dissolution windows (neutral pH suppression and acidic release)
- layered granules/microcapsules with seed cores and coating strata
In an FTO posture, the most sensitive parameter is the monomer-defined polymer requirement plus particle-size distribution.
What matters most for investors and licensing teams?
US 11,154,521’s enforceability and licensing value largely depend on whether it can be asserted against real products in the market that share:
1) the specific monomer-defined taste-mask polymer
2) layered particle architecture
3) particle size distribution
4) mass loading ranges
5) optional but helpful performance proof points (dissolution, plasma timing, taste panels)
Commercial relevance signals embedded in the claims
- Acidic vs neutral dissolution thresholds (Claims 25 and 26)
- Early plasma exposure against modified release comparators (Claim 24)
- Taste test comparative standard (Claim 23)
- Bioequivalence to non-taste-masked SPB (Claim 20)
These are the hooks that can drive licensing discussions and litigation proof frameworks.
Key Takeaways
- US 11,154,521 claims an oral SPB product made of layered particles with a seed core + SPB drug layer + taste-mask coating using a polymer formed from dimethylaminoethyl methacrylate, butyl methacrylate, and methyl methacrylate.
- Claim 1 is constrained by particle size (≥90% <500 μm) and strict mass fractions (seed core 10%-20%, SPB >60%, taste-mask coating 5%-25%).
- Dependent claims lock in key formulation options: HPMC binder, PEG 5,000 to 7,000 plasticizer, MCC seed cores, talc limits, and an optional seal coating.
- Performance claims add enforceable outcome criteria: neutral pH dissolution suppression, acidic pH dissolution completion, taste comparisons, and early plasma exposure versus modified release.
- The most direct design-arounds target the monomer-defined polymer, the particle size distribution, and/or the mass balance ranges.
FAQs
1) Which claim is the main infringement target?
Claim 1 is the independent scope: it requires layered particles with the specific monomer-defined taste-mask polymer, the particle size distribution limit, and the stated mass fraction ranges.
2) What particle size threshold does the patent require?
At least 90% of layered particles must be smaller than 500 μm (and smaller than 400 μm in the narrower Claim 21).
3) Does the patent require HPMC and PEG in the independent claim?
No. Claim 4 requires binder and plasticizer in the drug layer and Claim 5/6 specify HPMC and PEG 5,000 to 7,000, but those are dependent limitations. Claim 1 only requires SPB in the drug layer and the specified taste-mask polymer in the coating.
4) What dissolution profile does the patent target?
Neutral pH: <15% SPB dissolves over 10 minutes (Claim 25). Acidic pH: ≥95% SPB dissolves over 60 minutes (Claim 26).
5) What is the tightest composition lock-in in the claim set?
Claim 17 consolidates a specific set of mass fractions across SPB, HPMC, PEG, MCC, talc, and the monomer-defined taste-mask polymer.
References
- US Patent 11,154,521 (claims provided in prompt content).
