United States Patent 6,676,929: Scope, Claim Structure, and Landscape Impact
What does US 6,676,929 claim in plain patent terms?
US 6,676,929 is directed to a diagnostic imaging contrast agent defined by a chemical structure (the claims repeat the same concept with different substituent definitions) and to pharmaceutical compositions that include that agent plus a carrier and, in dependent form, a free organic ligand (or a pharmaceutically acceptable salt). The claim set you provided contains independent claim coverage that is structure-defined, plus composition claims that broaden practical use.
Claim architecture based on the text provided
- Claims 1-8: diagnostic imaging contrast agents defined by chemical structure formulas.
- Some dependent claims include explicit substitution definitions such as Ph = phenyl and Me = methyl.
- Claim 9: pharmaceutical composition containing:
- a contrast agent “according to any of claims 1-8”
- plus a carrier, adjuvant, or vehicle.
- Claim 10: composition of claim 9 further comprising:
- a free organic ligand or its pharmaceutically acceptable salt.
Core scope in one sentence
The patent scope is the set of structure-defined contrast agents covered by claims 1-8, plus formulations (claims 9-10) that include those agents and optionally add a free organic ligand.
How broad is the coverage for the contrast agent claims (1-8)?
Because claims 1-8 are structure-defined, the effective breadth is determined by:
- Which structural elements are fixed in the formula (ring system, chelating core, linker, charge-bearing groups).
- Which substituents are variable and how they are enumerated in dependent claims (e.g., Ph, Me).
- Whether the claims include Markush-like breadth (your excerpt does not show full formula scope, so the analysis is limited to what is visible: the substitution variable definitions “Ph=phenyl” and “Me=methyl” and the repeated “diagnostic imaging contrast agent having the following structure” language).
Based on the claim excerpt alone, the following is provable:
- The claims cover multiple species within a common structural framework (claims 1-8 differ only by the substituted group definitions shown in your excerpt).
- The patent does not appear to claim a method of imaging directly in the excerpt; it claims agents and compositions.
What is the practical expansion from the composition claims (9-10)?
Claim 9: formulation scope
Claim 9 covers a pharmaceutical composition comprising:
- a contrast agent as defined by any of claims 1-8
- and a carrier/adjuvant/vehicle.
This is standard but commercially important. It prevents design-arounds that switch delivery format while keeping the same active agent.
Claim 10: ligand-enabled scope
Claim 10 adds a further compositional limitation:
- the composition also contains a free organic ligand (or its salt).
This is a secondary axis of coverage: even if a competitor uses the same contrast agent, ligand inclusion can move them into or out of claim 10 depending on whether the competitor’s formulation matches the “free ligand” requirement.
How do “Ph=phenyl” and “Me=methyl” affect claim reach?
The presence of explicit substituent definitions indicates that:
- Some member compounds of the agent family are distinguished by specific substituents.
- Design-around risk is highest where competitors might choose alternative substituents not captured by the enumerated definitions.
In other words, the claims likely have a structural genus (same overall scaffold) but with protected enumerations in particular positions (phenyl and methyl appear explicitly in your excerpt). Substitution outside those defined groups can fall outside the literal scope, depending on how the full formula defines variables.
What is the likely claim interpretation for “free organic ligand”?
Within contrast-agent formulation practice, “free organic ligand” typically means an organic chelator or ligand that is not bound to the imaging metal center in the same way as a coordinated ligand complex. In legal claim terms, the limitation can be interpreted narrowly or broadly depending on:
- whether the claim requires the ligand to be “free” (not complexed to metal in the marketed form)
- and whether the ligand is required to be present as a separate species.
Your excerpt provides enough to state the limitation exists, but not enough to determine the breadth of what qualifies as “free” for this patent’s exact chemistry.
What is the strength and risk profile of this patent family position?
Even without the full specification text in your excerpt, the claim set structure suggests a typical pattern in imaging agent patents:
- Strength: structure-defined agent claims + formulation claims create two infringement routes:
1) selling or using a compound that matches claims 1-8
2) selling a matching compound in a covered formulation (claim 9), and potentially in a ligand-containing formulation (claim 10).
- Primary risk: structure-defined claims are vulnerable to:
- substitution changes at non-core positions
- alternative analog scaffolds not matching the exact formula elements
- Secondary risk: claim 10 narrows to formulations with a free organic ligand; competitors without that formulation element can fall outside the dependent claim (though they may still infringe claim 9 if the agent itself matches).
What is the patent landscape context likely to matter most?
For US contrast-agent patents, the landscape is usually dominated by:
- earlier chelated metal contrast agents (gadolinium-based, manganese-based, iron-oxide approaches, etc.)
- later macrocyclic vs linear chelator families
- formulation and ligand/stabilizer composition patents
- device and imaging modality patents (often methods), which can be separate from agent patents
However, to deliver a complete and accurate landscape mapping (priority chain, family members, assignee, citations, forward citations, expiration dates, and nearest blockers), the full bibliographic and claim text for US 6,676,929 is required. Your prompt includes only the claim excerpt and not the key metadata needed to build a legally grounded landscape.
Because this response must be complete and accurate, the landscape section below is constrained to what can be stated from the claim excerpt alone.
What can be concluded from the excerpt about infringement “hot spots”?
Hot spot A: matching the core scaffold
To infringe claims 1-8, a competitor must make, use, or sell a diagnostic imaging contrast agent that is within the claimed structure set. Substitutions not captured by the defined variables (e.g., Ph or Me where those are the only defined options) are the most plausible design-around lever.
Hot spot B: formulation inclusion
If a competitor uses a covered agent, claim 9 generally captures standard injectable formulation approaches (carrier/adjuvant/vehicle). That means a formulation change alone is unlikely to avoid claim 9 unless the active agent itself is changed or the product is reformulated in a way that negates a required element.
Hot spot C: adding or removing a “free organic ligand”
Claim 10 creates a narrower “extra coverage” lane. If a competitor formulates without a “free organic ligand,” they may avoid claim 10 while still facing claim 9 exposure.
What is missing for a true US 6,676,929 landscape claim chart?
A proper landscape analysis requires at least:
- full claim 1-8 formulas (not just the text placeholders)
- the patent’s bibliographic data (assignee, inventors, filing dates)
- cited references and prosecution history
- actual specification description of variable definitions and ligand identities
Your excerpt is insufficient to produce an infringement-grade claim chart against known competitors or to identify the closest prior art with precision.
Key Takeaways
- US 6,676,929 claims structure-defined diagnostic imaging contrast agents (claims 1-8) with explicit substitution definitions shown in your excerpt (Ph = phenyl; Me = methyl).
- It expands coverage to standard formulations via claim 9 (agent + carrier/adjuvant/vehicle).
- It further narrows additional coverage to formulations containing a free organic ligand via claim 10.
- The most likely infringement and design-around boundaries are (1) whether the competitor’s agent matches the claimed chemical structure and (2) whether the formulation includes a “free organic ligand.”
FAQs
1) Is US 6,676,929 aimed at imaging methods or agents?
The provided claims are aimed at diagnostic imaging contrast agents and pharmaceutical compositions including those agents.
2) Do claims 1-8 require specific substituents like phenyl or methyl?
Your excerpt shows explicit variable definitions including Ph = phenyl and Me = methyl, indicating those substituents are part of the claimed structure definitions for at least some claimed embodiments.
3) What does claim 9 add beyond the agent claims?
Claim 9 covers formulated products, requiring the claimed contrast agent plus a carrier, adjuvant, or vehicle.
4) What extra limitation does claim 10 impose?
Claim 10 adds a requirement for a free organic ligand (or a pharmaceutically acceptable salt).
5) Is it enough to change the formulation to avoid infringement?
For covered active agents, claim 9 typically captures standard formulation components; avoiding claim 10 may require omitting the free organic ligand, but avoiding claim 9 usually requires altering the active agent itself (or otherwise exiting claim elements).
References
[1] United States Patent 6,676,929.
