Scope and claims review for US Patent 9,271,941: what tablet formulations and manufacturing steps are actually covered
US 9,271,941 is a US formulation-and-process patent that claims a very specific active ingredient form and a narrow slice of oral solid dosage compositions. The claim set is dominated by (i) a single named API solvate (N-{…}acetamide dimethyl sulfoxide solvate), (ii) tight tablet composition constraints (drug dose in one of three mg amounts; excipient loading 25% to 89% by weight; “substantially free of water” excipients), and (iii) downstream manufacturing/quality attributes (micronization, particle size threshold, scale, and film coating including specific colorant descriptions).
From a freedom-to-operate standpoint, the enforceable perimeter is not “any tablet with that drug,” but tablets that meet all cited structural/functional limitations simultaneously, including solvate identity and excipient water content condition, plus optional claim-dependent add-ons (micronized particles, ≤30 micron particle-size distribution, film coating, colorant, minimum batch/scale).
What is US Patent 9,271,941’s active ingredient scope (solvate identity) in the claims?
Core limitation across claims 1–16: the tablet contains an amount of a single named drug substance:
N-{3-[3-cyclopropyl-5-(2-fluoro-4-iodo-phenylamino)-6,8-dimethyl-2,4,7-trioxo-3,4,6,7-tetrahydro-2H-pyrido[4,3-d]pyrimidin-1-yl]phenyl}acetamide dimethyl sulfoxide solvate (hereafter, “API DMSO solvate”).
Claim language consequences
- If a competitor uses the same pharmacological entity but a different solid form (e.g., another solvate, hydrate, polymorph, or amorphous form) and avoids “dimethyl sulfoxide solvate,” that design can fall outside the literal claim language.
- If a competitor uses “API DMSO solvate” but not at one of the explicitly recited dose amounts, claims 1–7 are not met (though other claims like 8–13 also still recite the same three dose options).
- The claims tie “substantially free of water” to excipients, not necessarily to the final tablet moisture. So a design that relies on hydrated excipients or excipients with significant water content can be noninfringing, depending on how “substantially free” is interpreted by the tribunal and evidentiary record.
What are the dose and excipient composition limits in the tablet claims?
A) Drug dose quantization
In claims 1–7 and 8–13, the drug amount is one of three specific quantities:
- about 0.5635 mg
- about 1.127 mg
- about 2.254 mg
This functions as a hard numerical limitation, not a broad “range” in these claims.
B) Excipients by weight
All tablet claims (1–15, and 8–13) include:
- from about 25% to about 89% by weight of one or more excipients
- excipients that are substantially free of water
The claim does not limit the excipient total to a single list until dependent claims 3–7/9–13; independent claims are broader on excipient identity but still enforce the water-content condition and the total excipient weight ratio.
How do micronization and particle-size limitations narrow claim scope?
Micronized drug particles (claims 2–7)
- Claims 2–7 require the drug particles are micronized.
So even if the correct solvate and tablet excipient constraints are satisfied, lack of micronization can avoid these dependent claims.
Particle size distribution (claims 8–13)
Claims 8–13 require:
- at least 50% of drug particles have a particle size of 30 micron or less
This is a distribution requirement. It can be avoided by:
- using a different milling regime, or
- ensuring the material distribution shifts such that fewer than 50% are ≤30 microns.
Overlap structure
- Claim 1: no micronization or particle-size distribution requirement.
- Claim 2–7: micronized particles required.
- Claim 8–13: particle-size distribution (≥50% ≤30 micron) required.
- Some dependent claims add film coating and colorants.
Which excipient identities are explicitly protected, and where?
Broader independent excipient coverage (claims 1, 8)
- Claims 1 and 8 do not require specific excipient identities, only:
- total excipient weight (25% to 89%)
- excipients “substantially free of water”
- and, for claim 8, the particle-size distribution
Explicit excipient list (claims 3–7 and 9–13)
Claims 3–7 and 9–13 restrict excipient identities to one or more of:
- microcrystalline cellulose
- powdered cellulose
- pregelatinized starch
- starch
- lactose
- Di-calcium phosphate
- lactitol
- mannitol
- sorbitol
- maltodextrin
These claims narrow the claim set compared with claims 1 and 8.
Tighter two-excipient variants (claims 14–15)
- Claim 14 (dependent on claim 6): excipients are limited to microcrystalline cellulose and mannitol.
- Claim 15 (dependent on claim 9): excipients are limited to microcrystalline cellulose and mannitol.
These appear aimed at a specific formulation composition. They do not cover tablets using other excipient systems unless they still satisfy the broader claims’ “selected from” language of those respective claims.
What film-coating and colorant limitations are claimed?
Film coating requirement (claims 4–7 and 10–13)
- Claims 4–7 add that the tablet is film coated.
- Claims 10–13 also require film coating.
Colorant requirements
- Claim 6 adds: film coating contains a colorant (no further specificity).
- Claim 7 specifies: colorant contains iron oxide.
- Claim 12 adds: film coating contains a colorant.
- Claim 13 specifies: colorant contains iron oxide.
So there are two enforcement layers:
- a broad “colorant included” layer (claims 6 and 12)
- a narrower “iron oxide present” layer (claims 7 and 13)
A competitor can potentially avoid the iron-oxide-specific dependent claims by using different pigments, but still risk infringement of the film-coated/colorant-inclusive claims if they include any colorant that meets the claim terms.
Is scale of production a claim limitation? What does “50,000 tablets” do?
Yes. Claims 5–7 and 11–13 include:
- tablet produced on a scale suitable to prepare at least about 50,000 tablets.
This is a production scale limitation embedded in the claim. Practically, it is likely to be treated as a manufacturing capability/throughput qualifier tied to the process and equipment scale and may be provable by production records. Designs using pilot-scale manufacture below that threshold could argue noninfringement for those specific dependent claims, even if other limitations match.
What process claim coverage exists under US 9,271,941?
Process claim 16
Claim 16 is the only process claim in the excerpted set. It claims a method comprising:
- Admixing:
- the API DMSO solvate (selected from the three dose amounts), and
- excipients that are “substantially free of water,” and
- further excipients,
- Compressing the mixture into tablets,
- The tablet ends up with:
- the specified drug amount
- excipients 25% to 89% by weight
- excipients “substantially free of water.”
Scope implications
- It does not include a full set of milling, granulation, drying, lubrication, or compression parameter requirements.
- It does not explicitly claim film coating, micronization, or particle-size thresholds in claim 16 (those appear in the tablet claims 2–13).
- Enforcement of the process claim is therefore likely to center on mixing and compression steps plus the excipient water-content and composition result.
How strong is the estate in terms of claim breadth versus narrowness?
Breadth drivers (why the patent is still commercially relevant)
- The API is uniquely specified, but once that API DMSO solvate is used, the tablet structural perimeter is fairly tight yet still leaves flexibility in excipient identity under independent claims (subject to water-free excipients and excipient loading).
- “Substantially free of water” is a condition that can be engineered, but it is also a common formulation goal for moisture-sensitive APIs and excipient stabilization.
- The claim set includes multiple independent structural variations (dose, excipient total, particle size distribution, micronization, film coat with/without iron oxide). That increases the probability that at least one claim maps to a real commercial formulation.
Narrowness drivers (why there are design-around routes)
- The dose is locked to three mg amounts in every claim presented here.
- The excipient water content condition is explicit.
- Particle-size distribution and micronization requirements are present only in certain dependent claims.
- Iron-oxide colorant is explicitly required for two of the film-coating dependent claims.
- The process claim is limited to admixing and compressing with the excipient water-content condition; it does not add further processing constraints.
What is the likely infringement “match test” for a generic or alternative tablet?
A practical mapping looks like this:
- API identity check
- Does the product use the API DMSO solvate specifically?
- Dose check
- Is the per-tablet amount approximately 0.5635 mg, 1.127 mg, or 2.254 mg?
- Excipients check
- Are excipients 25% to 89% by weight?
- Are the excipients “substantially free of water”?
- Optional add-ons
- If the formulation uses micronized drug particles, it is more likely to fall into claims 2–7.
- If at least 50% of drug particles are ≤30 microns, it is more likely to fall into claims 8–13.
- If film coated, it is more likely to fall into claims 4–7 and 10–13.
- If iron oxide is used as a pigment, it is more likely to fall into claims 7 and 13.
- If manufactured on a scale suitable for ≥50,000 tablets, it is more likely to meet claims 5–7 and 11–13.
This patent is therefore best characterized as “formulation-qualifying” rather than “functional” only. The solid form and moisture-related excipient condition are pivotal.
How does this claims set function as a patent landscape relative to other IP layers?
Within a typical small-molecule oral solid IP bundle, a patent like US 9,271,941 usually sits in the “formulation and manufacturing conditions” layer, not the “compound” layer. Even without the related-family data, the claim text indicates it is designed to protect:
- tablet dosage composition (solvate + dose + excipient loading + water-free excipients)
- and secondary manufacturing attributes (micronization and particle-size distribution)
- and appearance/formulation (film coating and pigments)
- plus a minimal processing method (admixture and compression)
That structure matters because in litigation, a defendant can often narrow by changing one axis (solid form, particle size, pigment, or excipient water content). The claim set increases coverage across axes, but does not cover every plausible variant of the API.
Key takeaways
- US 9,271,941 protects tablets containing the API dimethyl sulfoxide solvate at one of three mg doses (0.5635, 1.127, 2.254 mg).
- The tablet must include 25% to 89% by weight excipients that are substantially free of water.
- Dependent claim coverage expands protection to micronized particles and/or particle-size distribution (≥50% ≤30 microns).
- Film coating is covered, with additional pigment specificity: iron oxide is explicitly required in two dependent claims.
- A process claim covers admixture of the solvate with substantially water-free excipients and compression into tablets with the same composition constraints.
- Design-around pathways concentrate on: changing solvate/solid form, shifting dose, using excipients that are not “substantially free of water,” altering particle size distribution, and avoiding iron-oxide-containing pigments where those dependent claims are asserted.
FAQs
- Can a tablet infringe US 9,271,941 if it uses a different solvate or polymorph of the same drug?
- If a generic matches the API and dose but uses hydrated excipients, does that avoid the “substantially free of water” limitation?
- How do micronization and the “≥50% ≤30 microns” requirement differ for infringement analysis?
- Does film coating alone trigger the iron-oxide colorant dependent claims?
- What is the practical evidentiary target for proving the “produced on a scale suitable to prepare at least about 50,000 tablets” limitation?
References
No external sources were cited.
