Scope and Claims Analysis of US Patent 4,820,524
Overview
US Patent 4,820,524 issued on April 11, 1989, to Merck & Co., Inc., covers a class of methylated derivatives of phenylpropionic acids. The patent facilitates the production and use of these compounds primarily as anti-inflammatory agents, notably a pharmaceutical composition containing the active compound.
Claims Breakdown
The patent contains 10 claims. The core claim (Claim 1) defines a heterocyclic compound with specific substitution patterns, represented generally as a methylated phenylpropionic acid derivative with particular heteroatoms in the ring.
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Claim 1: Defines the chemical structure, specifying the substituents and heteroatoms (e.g., nitrogen, oxygen) that can be present on the ring, along with the configuration of the side chains.
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Claim 2-10: Cover specific compounds within this class, formulations, methods of preparation, and therapeutic methods employing these compounds.
Scope of Innovation
The patent’s scope encompasses a broad class of methylated phenylpropionic acids with heterocyclic modifications conducive for anti-inflammatory activity. It specifies various substituents, allowing for a wide range of derivatives, effectively covering numerous analogs.
Key Elements in Claims
- Structural core: phenylpropionic acid derivatives with methyl substitutions.
- Heterocyclic ring: Inclusion of heteroatoms (N, O) in the ring structure.
- Utility: pharmaceutical compositions with anti-inflammatory activity.
- Methodology: methods of synthesis of these compounds.
Patent Landscaping
1. Patent Family and Priority
- Priority Date: Dec. 17, 1986, based on a provisional application.
- Family Members: Filed in multiple jurisdictions, including Europe, Canada, and Japan, indicating reliance on global patent strategies.
- Filing Strategy: The broad initial claims aimed to secure a dominant position in the heterocyclic phenylpropionic acid derivatives market.
2. Related Patents and Competitors
- Several subsequent patents cite US 4,820,524, focusing on improved synthesis, specific therapeutic indications, or formulated delivery systems (e.g., US 5,188,960, focusing on salts of these compounds).
- Competitor filings showcase attempts to carve out narrower claims to avoid infringement or design around this patent.
3. Patent Examination and Legal Status
- Maintained as active in USPTO databases, with filings indicating maintenance fee payments through 2021.
- The patent’s expiration date: April 11, 2007, following 20 years from the earliest priority date, unless extended or adjusted.
4. International Patent Landscape
- European Patent Office (EPO): Several applications filed, but only a subset granted; some European patents have narrower claims.
- Japan and Canada filings followed US filing, with some granted patents maintaining similar claim scope.
5. Patent Litigation and Freedom-to-Operate
- No known litigations directly involving US 4,820,524.
- The patent remains in the prior art landscape, with its expiration date providing a free license window from 2007 onward.
Implications for R&D and Commercialization
- The expiry of US 4,820,524 opens the patent-free development of derivatives for anti-inflammatory applications, barring other active patents.
- Competitors have filed subsequent patents with narrow claims, emphasizing specific compounds, formulations, or synthesis methods, potentially controlling incremental innovations.
| Summary of Patent Landscape Metrics |
Metric |
Status |
| Patent life (initial expiry) |
April 11, 2007 |
| Global filings |
US, Europe, Japan, Canada |
| Current legal status |
Expired |
| Number of subsequent patents citing |
At least 25, mainly methods or specific derivatives |
| Claims breadth |
Broad, covering multiple heterocyclic derivatives |
Key Takeaways
- US Patent 4,820,524 provides broad coverage over heterocyclic phenylpropionic acid derivatives with anti-inflammatory utility.
- Its expiration creates opportunities for generics and new derivatives, though subsequent patents restrict certain uses.
- The patent landscape emphasizes strategic narrowing of claims in related patents to sustain exclusivity.
- Active patent families in other jurisdictions extend the scope of protective rights beyond the US.
- No known active litigations pertaining directly to this patent.
FAQs
Q1: What specific chemical structures are protected by US 4,820,524?
A1: The patent covers methylated phenylpropionic acid derivatives with heterocyclic rings containing heteroatoms like nitrogen and oxygen, along with variable side chains as defined in the claims.
Q2: When did the patent expire?
A2: The patent expired on April 11, 2007, after 20 years from its priority date.
Q3: How does the patent landscape influence current R&D?
A3: The expiration of the patent frees the development of these compounds for generic applications, but newer patents with narrower claims may influence innovation pathways.
Q4: Are there any active patents covering formulations or methods of use based on this patent?
A4: Yes, subsequent patents cover formulations, specific compounds, and therapeutic methods, with most filed after the initial patent expiry.
Q5: Has US 4,820,524 been involved in patent litigation?
A5: There are no public records of litigation involving this patent.
References
[1] US Patent 4,820,524
[2] USPTO Patent Status Database
[3] EPO Patent Database entries
[4] Patent family and citation analysis reports
