United States Patent 6,936,612 Scope, Claims, and U.S. Patent Landscape (Compound + Pharmaceutical Composition)
Executive summary: U.S. Patent 6,936,612 claims a single, specifically defined small-molecule structure (claim 1) and a two-part composition claim limited to that compound plus a conventional pharmaceutical carrier (claim 2). The claim scope is therefore narrow at the compound level and medium-to-broad at the formulation level (depending on how “carrier” and typical formulation limits are construed). Patent landscape analysis for a compound-specific claim should prioritize (i) continuation or related filings from the same assignee, (ii) alternative crystal/polymorph, salt, and hydrate forms, (iii) prodrugs and solvate forms, (iv) method-of-use (if any) tied to the same scaffold, and (v) later process patents covering commercial manufacturing of that exact API.
What is the scope of US patent 6,936,612 and what exactly do claims cover?
Claim 1 (compound): The patent is directed to one enumerated chemical entity:
6-Acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one.
Because the claim is defined by a full IUPAC-style chemical name, the scope is limited to that precise structure (and, in practice, close equivalents only to the extent the doctrine of equivalents applies, which is tightly constrained for chemical structure claims in U.S. litigation).
Claim 2 (pharmaceutical composition): A “pharmaceutical composition” comprising:
- a therapeutically effective amount of the compound of claim 1, and
- a pharmaceutical carrier.
This is a classic “API + carrier” formulation claim. It does not, on its face, specify dosage form, release mechanism, excipients, route of administration, or particle form. That pushes scope toward a wide range of standard oral or injectable presentations, while still requiring the asserted compound as the active ingredient.
How narrow is the compound claim in practice?
A structure claim of this specificity typically covers:
- the claimed free base form as such (if the name implies a base),
- the exact stereochemistry if specified or inherent,
- the exact ring system connectivity (pyrido[2,3-d]pyrimidin-7-one fused core),
- the substituent pattern:
- 6-acetyl
- 8-cyclopentyl
- 5-methyl
- 2-(5-piperazin-1-yl-pyridin-2-ylamino)
- 7-one carbonyl (lactam/one motif)
It typically does not automatically include:
- salts (e.g., HCl, mesylate) unless the “compound” construction in litigation treats salt as encompassed or equivalents,
- polymorphs and hydrates unless the claim language is construed to cover those forms or there are additional dependent claims (not provided here),
- analogs (even minor changes like different alkyl substitution on the pyridine ring or replacement of piperazine with a different amine).
How broad is the composition claim in practice?
Claim 2 is broad because:
- it covers “a pharmaceutical composition” with “a pharmaceutical carrier,” without limiting carrier type,
- it does not limit route (oral, parenteral, etc.) or dosage form.
However, typical infringement requires proof that the accused product contains the claimed compound (as an API or as a substantial component), and that it is used at a “therapeutically effective amount.” In chemical/pharmaceutical disputes, the largest litigation leverage often comes from whether the accused product uses:
- the same chemical entity,
- a salt/prodrug/polymorph that is argued to fall outside the “compound” definition,
- a different analog that lacks the claimed substitution pattern.
Which parts of the claimed molecule drive claim scope and design-around risk?
Structural “anchors” that usually control claim boundaries:
- Pyrido[2,3-d]pyrimidin-7-one scaffold
- Exact substitution pattern at 2, 5, 6, and 8
- 2-position side chain identity
- 2-(5-piperazin-1-yl-pyridin-2-ylamino) is a multi-part substructure with its own ring connectivity
High design-around sensitivity:
- Changing the amino-connection to the pyridine ring or shifting the piperazine substitution position changes the structure.
- Replacing piperazine with a different diazacycle or mono-amine changes the side chain.
- Moving the acetyl group off position 6 or changing it to another acyl group changes the claim.
Lower sensitivity (often easier to adjust without affecting novelty, but may still be infringement-relevant):
- Salts and particle form may be argued to be encompassed by “compound” or by equivalence, depending on claim construction and how the inventors described the compound in the specification (not provided here).
- Formulation excipients are typically not relevant to infringement if the API is the same.
What patent landscape issues matter around a compound + carrier composition claim like this?
For a compound-specific patent with an API composition claim, the most relevant competing IP buckets in the U.S. are:
1) Related patents on the same scaffold (continuations, analogs, and broader Markush sets)
Because claim 1 is single-entity, the business question becomes whether the assignee has:
- continuation claims with broader genus coverage,
- dependent claims on salts, polymorphs, or solvate forms,
- additional patents covering stereochemical variants or prodrugs.
Why it matters: If a later patent broadens coverage to salts/polymorphs/prodrugs, infringement and “generic substitution risk” change materially.
2) Salt, polymorph, hydrate, and crystal form patents
If commercial products use a specific solid form, landscape analysis must identify whether:
- the marketed API is a specific salt form,
- the dosage uses a particular polymorph or hydrate.
Why it matters: Even if claim 1 is framed as a “compound,” some litigation turns on whether a salt is considered the same compound or a different chemical entity.
3) Method-of-use patents
If the molecule is tied to a medical indication, method-of-use claims can create additional exclusivity layers even when compound claims narrow.
4) Process/method-of-manufacturing patents
If later process patents exist, they can deter generic entry via manufacturing design-around, even when formulation patents are weaker.
5) Composition and formulation patents beyond Claim 2
Claim 2 is a basic carrier claim. Competitors often file separate patents on:
- controlled-release matrices,
- coating systems,
- particle size distributions,
- bioavailability-improving formulations.
What do U.S. regulatory and market entry risks look like for claim 1/claim 2 coverage?
This section normally depends on the Orange Book listing (application number, NDA/BLA, listed patents, and expiration data) and on actual products using the exact API. No Orange Book identifiers were provided, so only the structural risk framework can be stated.
If a generic launches an ANDA for the same API
Key legal fact pattern:
- If the ANDA references an approved drug and includes the same compound, claim 2’s carrier language usually does not restrict generic formulation because carriers/excipients are standard.
- The main design-around question is whether the generic uses the same claimed compound or a salt/prodrug that is argued to fall outside claim 1.
Paragraph IV challenge typical for this claim type
For a compound-specific API patent with a formulation companion, a generic’s Paragraph IV filing often argues:
- non-infringement (structure difference, different salt form, or different prodrug),
- invalidity (anticipation/obviousness) if prior art exists.
Because the claims provided here are only claim 1 and claim 2, and no prosecution history or cited art are provided, the only actionable insight is that challenges frequently target:
- whether the claimed entity is disclosed by earlier references,
- whether the combination of scaffold and substituents was routine in the art.
How does claim scope of US 6,936,612 compare with typical formulation-only patents?
Compared to formulation-only patents:
Claim 2 is broader than many formulation patents because it is not limited to:
- a specific dosage form,
- a specific release profile,
- specific excipient quantities,
- a specific route.
Compared to Markush/genus patents:
Claim 1 is narrower than a genus claim. It is not a “compounds of Formula I” claim with interchangeable substituents. It is an enumerated structure.
Net effect:
- Stronger deterrence against products using the exact API.
- Weaker deterrence against close analogs, unless those analogs are captured by other patents (not provided here).
What likely additional claims or related IP are adjacent to this scaffold in U.S. filings?
Even without the rest of the claim set, the typical adjacent estate for a patented small-molecule scaffold includes:
Solid-state variants
- salts (e.g., hydrochloride, acetate, mesylate)
- polymorphs and hydrates
- amorphous forms
Prodrugs
- esterification of functional groups to improve absorption
- conversion into the parent compound in vivo
Biomarker-linked methods
- dose-ranging or patient selection methods tied to target engagement
Manufacturing/process
- crystallization steps
- purification of intermediates
- final API isolation and polymorph control
This is the most common pattern for compound + carrier estates: an API claim is paired with at least one additional patent category that covers commercially relevant manufacturing and solid-state control.
How strong is the patent estate for US 6,936,612 likely to be, based on claim design?
On the face of the claim language you provided:
- Claim 1 is strong in exclusivity scope because it is an exact chemical entity.
- Claim 2 is strong but depends on API identity. If a competitor uses the same compound, claim 2 is typically easy to assert.
- Validity pressure typically comes from prior art chemistry. Single-entity claims often face anticipation/obviousness risk if the substitution pattern was already taught or if the scaffold was known with predictable substitution.
The primary commercial risk for competitors is not whether they can formulate a dosage form; it is whether they can source or synthesize a non-infringing chemical entity and still be therapeutically equivalent.
Key takeaways
- U.S. Patent 6,936,612 is centered on a single enumerated API: 6-Acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one (claim 1).
- Claim 2 is a broad, conventional API + pharmaceutical carrier composition claim with no dosage-form or route limits.
- Design-around primarily depends on changing the exact chemical identity at the level of the scaffold/substituents. Salt/polymorph/form differences may or may not avoid claim 1 depending on claim construction and specification support.
- The most material landscape work for business decisions is to map the rest of the assignee’s U.S. estate around this scaffold: continuations, crystal form/salt patents, prodrugs, method-of-use, and process patents.
FAQs
1) Does claim 2 of US 6,936,612 cover every dosage form containing the compound?
It covers a composition with a therapeutically effective amount of the claimed compound and a pharmaceutical carrier, so it is not limited to a specific dosage form in the claim text you provided.
2) Can a generic avoid infringement by switching to a salt form of the compound?
Infringement turns on whether the salt is construed as the “compound” of claim 1 or treated as equivalent. The claim text alone does not resolve that.
3) Are polymorphs and hydrates automatically covered by claim 1’s chemical name?
Not automatically. Coverage depends on claim construction and whether the solid forms are treated as the same compound for claim purposes.
4) What is the main litigation focus for an API-specific claim like claim 1?
Whether the accused product uses the exact claimed structure (or is a close equivalent) and whether prior art discloses or makes obvious the specific substitution pattern.
5) Does claim 2 increase generic entry risk after claim 1 is challenged?
Yes, if the generic uses the same claimed API. A carrier-based composition claim often remains relevant even if some formulation details differ, unless the API identity is changed.
References
No sources were provided with the prompt, and no external bibliographic identifiers (assignee, application number, Orange Book listing, or prosecution/cited art) were included.
