United States Patent 8,481,083: Scope, Claim Boundaries, and Landscape
What does US 8,481,083 claim, in plain scope terms?
US 8,481,083 claims a two-granule pharmaceutical composition for oral dosing, where each granule type has a specific core and coating:
1) Magnesium oxide (MgO) coated granules
- A core of citric acid
- A spray-coated or coated layer of magnesium oxide on the citric acid core
2) Sodium picosulphate coated granules
- A core of potassium bicarbonate
- A spray-coated layer of sodium picosulphate on the potassium bicarbonate core
The claims then narrow with particle size, granule size distributions, and coating thickness, and they add optional excipients (saccharin sodium; orange flavoring).
Core claim (Claim 1) elements that define infringement boundaries
Claim 1 requires all of the following in a single composition:
- MgO-coated granules where MgO is layered on a citric acid core
- Sodium picosulphate-coated granules where sodium picosulphate is layered on a potassium bicarbonate core
- The composition is “pharmaceutical” and therefore intended for oral use, but the legal trigger is the structure of the granules and coatings.
Textually, Claim 1 does not impose:
- a specific dosage ratio between the two granule types
- a specific manufacturing method
- a specific process for in-situ formation beyond the solution statement in Claim 8
- a defined coating method for both layers beyond “coated granules” and “spray-coated layer” language for sodium picosulphate
Those absences matter: Claim 1 is structurally specific on the granules, not on how they are made.
How narrow are the dependent claims that quantify the granule geometry?
Claims 2 to 7 materially narrow the composition by specifying MgO coating thickness and granule particle size/distribution.
MgO coating thickness limits (Claims 2 and 3)
- Claim 2: MgO layer thickness is 2 to 15 μm
- Claim 3: MgO layer thickness is 5 to 10 μm
Legal impact:
- Claim 3 is a subset of Claim 2. A product with MgO thickness outside 2–15 μm will not satisfy either.
- Products within 5–10 μm fall under both Claim 2 and Claim 3.
MgO-coated granule size breadth and size distribution (Claims 4 to 7)
- Claim 4: MgO-coated granules are 450 to 800 μm at their “broadest point”
- Claim 5: MgO-coated granules have particle size about 100 μm to 900 μm
- Claim 6: >85% of MgO-coated granules have size 100 μm to 900 μm
- Claim 7: <5% of MgO-coated granules are >900 μm OR <5% are <100 μm
Legal impact:
- These claims are distribution-sensitive. Two batches with the same average size can differ on the >85% and <5% cutoffs and thereby escape dependent-claim coverage even if they still arguably meet Claim 1 at a high level.
- Claim 4 is “broadest point” 450–800 μm, which is not identical to Claim 5’s particle size range. A design could hit one and miss the other if the geometry is nonuniform.
Practical claim mapping (MgO-coated granules only)
| Parameter |
Claim coverage |
Hard cutoff test |
| MgO layer thickness |
2–15 μm (Claim 2); 5–10 μm (Claim 3) |
coating microns must fall within range |
| “Broadest point” granule size |
450–800 μm (Claim 4) |
geometric breadth must fall within range |
| particle size |
100–900 μm (Claim 5) |
size measurement method must place majority within bounds |
| distribution |
>85% in 100–900 μm (Claim 6) |
fails if majority falls outside 100–900 |
| tail controls |
<5% >900 or <5% <100 (Claim 7) |
fails if outliers exceed 5% threshold |
What does Claim 8 do to the in-solution chemistry story?
- Claim 8: MgO and citric acid form magnesium citrate in solution.
Scope impact:
- This is a functional/chemical consequence claim element. It ties the MgO-on-citric acid configuration to an expected outcome during dissolution.
- It does not define a separate coating thickness or particle size, so it generally tracks any product meeting Claim 1 where dissolution yields magnesium citrate.
Potential boundary:
- Products using citric acid as the core but not forming magnesium citrate in solution (for example, if chemical state is altered) could argue noncoverage. Practically, most formulations with MgO + citrate at physiological/pH dissolution conditions will form magnesium citrate, but Claim 8 is still an additional requirement for that dependent claim.
What excipients expand coverage (Claims 9 to 11)?
These are simple add-on limitations:
- Claim 9: additionally comprises saccharin sodium
- Claim 10: additionally comprises orange flavoring
- Claim 11: additionally comprises saccharin sodium and orange flavoring
Legal impact:
- These dependent claims expand coverage only to compositions that contain the named excipients. Products without both can still infringe Claim 1–8 if they meet the structural granule limits, but would not satisfy Claims 9–11.
What is the likely product and use category targeted by this patent family?
Even without relying on extra claim text, the granule design is strongly consistent with:
- MgO on citric acid to generate magnesium-containing ionic species after dissolution
- sodium picosulphate on potassium bicarbonate as a pH-responsive trigger system (bicarbonate presence supports local conditions for drug activation/release)
That combination is characteristic of oral, taste-managed pharmaceutical products intended to deliver actives via granules with delayed or localized release behavior.
Where are the core infringement gaps: what must a challenger avoid?
For a competitor to design around, it must avoid one or more of the Claim 1 core granule architecture elements, or miss the dependent quantified ranges.
Most direct design-around levers
1) Change the core of the sodium picosulphate granule
- Claim 1 requires a potassium bicarbonate core under the picosulphate coating.
- Using a different carbonate/bicarbonate or a different core eliminates that element.
2) Change the core of the MgO granule
- Claim 1 requires a citric acid core under the MgO coating.
- Using a different acid (or uncoated MgO particles, or a different acid-core) avoids the literal core requirement.
3) Change the coating vs. mixed formulation structure
- Claim 1 uses “magnesium oxide coated granules” and “sodium picosulphate coated granules” with spray-coated layer language for the latter.
- If the formulation is not layered granules (for instance, mixed excipient blend rather than core-shell granules), it can avoid the “coated granules” requirement.
Dependent-claim design-around levers
If a product keeps the Claim 1 architecture but shifts measurable parameters outside ranges:
- MgO thickness not within 2–15 μm (or 5–10 μm)
- MgO granule “broadest point” not within 450–800 μm
- particle size distribution not meeting 100–900 μm dominance (>85% criterion) or tail limits (<5%)
Scope summary: claim-by-claim “coverage matrix”
| Claim |
Required elements |
Quantitative limits present? |
Add-on excipients? |
| 1 |
MgO-coated on citric acid core + sodium picosulphate-coated on potassium bicarbonate core |
No |
No |
| 2 |
Claim 1 + MgO layer thickness 2–15 μm |
Yes |
No |
| 3 |
Claim 1 + MgO layer thickness 5–10 μm |
Yes |
No |
| 4 |
Claim 1 + MgO-coated granules 450–800 μm broadest |
Yes |
No |
| 5 |
Claim 1 + MgO granule particle size ~100–900 μm |
Yes |
No |
| 6 |
Claim 1 + >85% of MgO granules 100–900 μm |
Yes |
No |
| 7 |
Claim 1 + <5% MgO granules >900 μm OR <5% <100 μm |
Yes |
No |
| 8 |
Claim 1 + MgO and citric acid form magnesium citrate in solution |
Functional element |
No |
| 9 |
Claim 1 + Claim 9 excipient saccharin sodium |
No |
Yes |
| 10 |
Claim 1 + orange flavoring |
No |
Yes |
| 11 |
Claim 1 + saccharin sodium + orange flavoring |
No |
Yes |
What does the patent landscape likely look like around this claim set?
Without the application bibliography (priority filing, family members, related continuation/divisional status), the landscape assessment must focus on claim-anchored design zones that typically attract related patents in this domain:
Likely “adjacent” patent clusters that intersect this claim scope
1) Core-shell granule coating patents
- Core-shell structures for taste masking, pH-responsive activation, or controlled dissolution.
2) picosulphate and bicarbonate activation systems
- Patents that pair sodium picosulphate with bicarbonate/carbonate species or pH modifiers.
3) magnesium oxide with citrate stabilization/interaction systems
- Patents that form magnesium citrate in dissolution or manage MgO reactivity, taste, or moisture sensitivity.
4) Granule size and coating thickness parameterization
- Patents that define particle size distributions and coating microns to improve consistency and dissolution.
Practical competitive implication
A product is at higher legal risk if it:
- uses citric acid cores coated with MgO
- combines that with potassium bicarbonate cores coated with sodium picosulphate
- then controls MgO coating thickness and MgO granule size distributions as in Claims 2–7
If those features are present, the key question becomes whether the competitor can avoid exact core identity (citric acid; potassium bicarbonate), coated granule architecture, and/or the defined thickness and granule size distributions.
Key takeaways
- Claim 1 is the structural anchor: infringement turns on MgO coated on citric acid cores combined with sodium picosulphate coated on potassium bicarbonate cores in one pharmaceutical composition.
- Claims 2–7 are parameter locks that can be used to design around by shifting MgO coating thickness and MgO granule size/distribution out of the specified ranges.
- Claim 8 adds a chemistry outcome: MgO + citric acid forming magnesium citrate in solution.
- Claims 9–11 add formulation excipients: saccharin sodium and orange flavoring.
FAQs
1) Does Claim 1 require specific amounts of magnesium oxide or sodium picosulphate?
No. Claim 1 requires the granule structure (core and coating identity). It does not state dosage ratios in the claim text provided.
2) If a competitor uses citric acid cores but not MgO as the coated layer, is Claim 1 met?
No. Claim 1 requires a magnesium oxide coated layer on the citric acid core.
3) If a competitor uses potassium bicarbonate cores but coats them with a different active instead of sodium picosulphate, is Claim 1 met?
No. Claim 1 requires the coated layer of sodium picosulphate.
4) What is the strongest dependent-claim leverage for design-around?
Claims 2–7, because they impose hard numerical ranges on MgO coating thickness and MgO granule size/distribution cutoffs.
5) Are saccharin sodium and orange flavoring required for infringement?
No. Those are only in dependent claims (9–11). A product can infringe Claim 1–8 without containing saccharin or orange flavoring.
References
[1] United States Patent No. 8,481,083.
