Scope and Claims Analysis for U.S. Patent 11,213,528: Sustained-Release Pharmaceutical Composition of (R)-3-(4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl)-3-cyclopentylpropanenitrile Phosphoric Acid Salt
U.S. Patent 11,213,528 is a formulation patent focused on a single active pharmaceutical ingredient (API) defined by stereochemistry, chemical identity, and salt form, combined with pharmaceutically acceptable excipients, with claim coverage anchored to sustained release and specific dosage-form and excipient/unit features. The claims are written to capture both oral and topical sustained-release compositions, with additional narrowing to unit dosage forms (tablet/capsule) and an enteric layer option. The patent’s commercial leverage is strongest against generic or follow-on products that use the same API salt form and replicate the patented release profile and dosage architecture.
What does U.S. Patent 11,213,528 claim coverage include and exclude?
Claim center of gravity: a pharmaceutical composition comprising
- the specific compound: (R)-3-(4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl)-3-cyclopentylpropanenitrile phosphoric acid salt, and
- pharmaceutically acceptable excipients,
with the composition being suitable for providing sustained release.
Hard inclusion elements (must all be present for infringement risk on the independent claim):
- The API must be the specified (R)-enantiomer and must be the phosphoric acid salt.
- The composition must include pharmaceutically acceptable excipients.
- The composition must be suitable for sustained release (functional limitation tied to release behavior).
Hard exclusions implied by the claim text:
- Substituting a different salt (e.g., hydrochloride, sulfate, mesylate) avoids literal coverage of the salt-specific definition.
- Using the racemate or the S-enantiomer avoids the (R)-specific identity.
- Omitting sustained release functionality (immediate release) avoids the “suitable for providing sustained release” limitation in claim 1.
Scope note that drives enforcement strategy:
- Claim 1 is broad on excipient identity and dosage route, but narrow on API identity and sustained release.
- Dependent claims add additional structural/dosage constraints that can create multiple infringement “lanes” if a product fits any dependent combination.
How broad is “suitable for providing sustained release” in claim 1?
The term “suitable for providing sustained release” is a functional limitation rather than a numeric dissolution or pharmacokinetic threshold in the claim set you provided. That typically expands practical claim coverage because infringement can be argued via formulation performance (release profile), not only via explicit percentages of polymer, matrix composition, or dissolution specifications.
In enforcement terms, the sustained-release limitation gives the patent flexibility to attack:
- controlled-release matrices,
- coated tablets with delayed/extended dissolution,
- multipart systems designed to extend drug release.
But it also introduces a contestable element: whether the accused product meets the sustained-release capability. The claims, as provided, do not specify:
- time-to-peak,
- dissolution medium conditions,
- percent released at 1/2/4/8/24 hours,
- Cmax or AUC shaping parameters.
That omission tends to keep claim 1 “capable of sustained release” in play, but it leaves validity and infringement fights likely to hinge on experimental release data and expert analysis.
Which dependent claims narrow the formulation scope most?
Unit dosage form and dosage container constraints
- Claim 2: composition is a unit dosage form.
- Claims 3–4: unit dosage form is a tablet or capsule.
These dependents let the patent holder pursue infringement theories tailored to the product form the manufacturer sells.
Enteric layer option
- Claim 5: unit dosage form further comprises an enteric layer.
This can matter if the commercial product uses:
- enteric coating for pH-dependent delay,
- layered release architecture combining enteric protection with extended release.
Claim 5 is a meaningful narrowing element but also creates a targeted claim lane for manufacturers using enteric film coats.
Dosage amount range
- Claim 6: unit dosage contains about 5 to about 1000 mg of the compound.
This range is extremely wide, which usually means most commercial tablet/capsule strengths likely fall within it. The key is whether the accused product’s per-unit dose of the API salt is outside the asserted range. In practice, it is uncommon to be outside 5–1000 mg if the product is a conventional small-molecule oral dose.
Excipients list: broad but pinned to a defined set of commonly used materials
- Claim 7: excipients comprise one or more from a long list: lactose, dextrose, sucrose, sorbitol, mannitol, starches, gum acacia, calcium phosphate, alginates, tragacanth, gelatin, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, water, syrup, methyl cellulose.
- Claim 8: microcrystalline cellulose is an excipient.
- Claim 9: microcrystalline cellulose plus lactose.
- Claims 11 and 10: Claim 11 is “lactose” as an excipient in claim 1; Claim 10 narrows to lactose + tablet (dependent on claim 9).
These dependent claims are “formulation-pattern” claims. They provide additional hooks against generic copycats likely to use standard direct compression/lactose excipient systems and MCC as a filler/binder.
Salt crystallinity and stoichiometry
- Claim 12: the salt is a crystalline salt.
- Claim 13: crystalline salt is a 1:1 compound:phosphoric acid salt.
- Claim 14: unit dosage form is a tablet.
Crystallinity and stoichiometry limitations are strong legal differentiators. If an accused product uses an amorphous form, hydrates, different polymorphs, or a different stoichiometry, the patent may not read on those dependent claims. Claim 1 still covers the salt as such, but claims 12–14 can be decisive in narrowing enforcement to a specific solid-state form.
Route-dependent extension (oral vs topical)
- Claim 15: sustained release suitable for oral administration.
- Claim 16: sustained release suitable for topical administration.
This is unusual in that the patent text you supplied explicitly spans both oral and topical routes. That can expand infringement surface area across different market concepts, but it also suggests the underlying disclosed formulation technologies may be broad. Practically, the “topical sustained release” lane only matters if there is a real commercial topical product using the same API salt.
What is the enforceable “claim lattice” mapping to product design?
Below is a compact mapping of which claim combinations correspond to which product design choices.
| Product attribute |
Claim(s) triggered |
Practical design patterns that fit |
| Same API identity: (R)-enantiomer + phosphoric acid salt |
Claim 1 + all dependents |
Avoids most easy design-arounds unless salt/enantiomer match |
| Sustained-release performance |
Claim 1 + all dependents that depend on claim 1 |
Extended release matrices, coated beads/tablets, multipart systems |
| Unit dosage form |
Claim 2 |
Tablet/capsule packaging units |
| Tablet vs capsule |
Claims 3–4 |
Solid oral dosage form |
| Enteric layer |
Claim 5 |
pH-dependent delay + sustained release |
| Dose per unit 5–1000 mg |
Claim 6 |
Most standard strengths likely fall within range |
| Lactose and MCC-based excipient system |
Claims 7–11 + 8–10 |
Common direct compression systems |
| Crystalline 1:1 salt |
Claims 12–14 |
Solid-state control through polymorph/formulation |
| Oral vs topical |
Claims 15–16 |
Route-specific sustained-release products |
How many patents typically cover an API salt + sustained release, and where does this one sit?
With only the claim text provided, a complete US patent landscape count cannot be produced. The claims themselves indicate this is a formulation patent rather than a core compound or medical use patent. In a typical lifecycle for small molecules, a formulation patent like this often coexists with:
- composition-of-matter patents covering the API,
- polymorph or salt patents,
- process patents for making the salt,
- method-of-use or treatment patents.
U.S. Patent 11,213,528’s claim structure shows it is positioned specifically to block “generic-style” reformulations that keep the same salt but change excipients or packaging in a manner inconsistent with sustained-release design.
What product changes would most reduce infringement risk?
Given the literal claim language you supplied, the main design-around levers are:
1) Switch the salt form
If the accused product uses a different acid salt than phosphoric acid, it can avoid the defined API identity in claim 1. This is the clearest structural design-around in the claim set.
2) Use a different stereochemical form
If the formulation uses S-enantiomer or racemate, it may fall outside the (R)-defined active ingredient scope.
3) Remove sustained-release functionality
If an accused product is immediate-release, it can avoid the “suitable for providing sustained release” limitation in claim 1.
4) Avoid the specific solid-state constraints (for dependent claims)
- If the product is not a crystalline salt, it may avoid claims 12–14.
- If it uses a non-1:1 stoichiometry form, it may avoid claim 13.
5) Avoid certain dosage-form architectures
- If the commercial product is not a tablet or capsule (e.g., sachet/granules without unit dosage form as framed), it may reduce dependent-claim applicability.
- If there is no enteric layer, claim 5 may not read.
The independent claim still remains the most important test because it is broad on dosage container type and excipient selection.
What would likely be the infringement arguments in litigation over this patent?
Core claimant argument (based on the claim set)
- The accused product contains the exact (R) phosphoric acid salt API.
- The product uses a sustained-release technology proven by dissolution testing or in vivo performance.
- The product includes standard excipients common to claims 7–11, or at least includes excipients broadly covered under the “pharmaceutically acceptable excipients” clause.
- If the accused product uses lactose and MCC, claims 8–10 and 11 are directly implicated.
Core defendant argument (based on claim wording)
- Challenge sustained-release qualification (how the release profile is defined and measured).
- Challenge API identity through solid-state characterization: crystalline form, stoichiometry, and potentially polymorph/hydrate if the formulation changes the salt’s form while keeping an “effective” drug substance.
- If the accused product uses another salt or enantiomer, argue non-infringement on claim 1’s active ingredient definition.
How strong is the patent estate for sustained-release compositions given this claim set?
Strength is driven by:
- Specific API identity (high certainty for enforcement when matched, high escape for design-arounds via salt/enantiomer).
- Sustained-release functional limitation (litigation tends to become technical, but it also captures many controlled-release designs).
- Dependent claims on excipient patterns and solid state (useful as alternative infringement paths, especially where generics use standard lactose-MCC systems and controlled crystallinity).
Weakness risk is also predictable:
- If a competitor uses a different salt form, most of the estate’s value collapses for literal infringement.
- If sustained release is argued as not “suitable” based on dissolution performance, claim 1 becomes an expert-driven fight.
On balance, for a manufacturer that is already using the same API salt and sustained-release platform, this patent can be operationally difficult to route around because the dependents cover common excipient stacks and tablet/capsule formats.
Orange Book status, FDA reference product, and Paragraph IV risk
Those elements cannot be determined from the claim text alone. A complete Orange Book status and Paragraph IV landscape requires the FDA publication and listed patents for the specific NDA/ANDA/BLA that references the active ingredient and dosage forms. Without those links, it is not possible to produce an accurate exclusivity timeline, generic entry risk date, or litigation mapping tied to FDA filings.
Key Takeaways
- U.S. Patent 11,213,528 is a formulation patent anchored to a single defined API: (R)-3-(4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl)-3-cyclopentylpropanenitrile phosphoric acid salt.
- The independent claim requires a composition suitable for sustained release, plus pharmaceutically acceptable excipients; dependents target unit dosage forms (tablet/capsule), enteric layer, dose range (5–1000 mg), lactose/MCC excipient patterns, and crystalline 1:1 salt.
- The clearest design-arounds are changing salt form, changing stereochemistry, or moving away from sustained-release performance.
- The patent is most enforceable against products that match the salt identity and use standard sustained-release architectures using lactose/MCC and/or crystalline solid-state control.
FAQs
1) Does claim 1 require an enteric layer?
No. An enteric layer is only required for the dependent configuration in claim 5.
2) Can a capsule avoid infringement of the tablet-dependent claims?
Yes for the tablet-specific dependents (e.g., claim 3/10/14 depend on tablet), but claim 1 and general unit dosage claim coverage can still apply if the product is a capsule with sustained release.
3) Is crystallinity required to infringe claim 1?
No. Crystallinity is a dependent limitation in claims 12–14; claim 1 covers the salt generally.
4) What excipients are specifically enumerated in the claims?
The claims enumerate many excipients including lactose, MCC, PVP, methyl cellulose, alginates, gelatin, and starches. Dependent claims emphasize MCC and lactose combinations.
5) Does the patent cover both oral and topical sustained-release products?
Yes. Claims 15 and 16 expressly cover sustained release suitable for oral administration and sustained release suitable for topical administration.
References
- U.S. Patent 11,213,528 (claims text provided by user).
