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Patent landscape, scope, and claims: |
Analysis of US Patent 4,594,359: Scope, Claims, and Patent Landscape
What is the scope of US Patent 4,594,359?
US Patent 4,594,359, filed on April 10, 1984, and granted on June 10, 1986, covers a method of synthesizing a specific class of anti-inflammatory compounds. The patent encompasses a broad approach to preparing substituted arylacetic acids, particularly derivatives of mefenamic acid, with pharmaceutical applications targeting inflammation and pain relief.
Core invention details:
- The patent claims a process for producing N-arylalkyl or N-arylalkylarylalkyl derivatives.
- It emphasizes chemical modifications at the carboxylic acid group of mefenamic acid, introducing various substituents to enhance activity or pharmacokinetic properties.
- The claims include various substitution patterns on the aromatic rings, which broadens the scope to multiple analogs within the same chemical framework.
Legal scope considerations:
- The claim language defines a class of compounds characterized by a core anthranilic acid structure with specific substitutions.
- The patent covers both the chemical process for synthesizing these derivatives and the compounds themselves.
- It explicitly claims intermediates and target compounds, making it relevant for subsequent patent filings involving similar chemical structures.
How broad are the claims?
The claims of US Patent 4,594,359 are considered medium to broad within its chemical class:
- Compound claims: Cover multiple derivatives differing in substitution patterns, with exclusions mainly limited to specific, explicitly enumerated compounds.
- Process claims: Encompass general methods for synthesizing these derivatives, not limited to particular reaction conditions or reagents.
- Scope impact: The breadth permits a wide range of mefenamic acid analogs to be protected, encouraging innovation within this chemical framework but also raising risk for generic competition if broad claims are upheld.
Claim limitations:
- The claims specify certain substituents and their positions, which can constrict the scope if particular substituents are deemed essential.
- The patent's priority date predates many modern synthetic techniques, potentially limiting its relevance against newer approaches.
Patent landscape surrounding US Patent 4,594,359
Key related patents:
- Subsequent patents have built upon this proprietary framework, notably:
- US Patent 4,727,148 (filed 1984) covering specific mefenamic acid derivatives.
- US Patent 4,578,308 (filed 1984) related to pharmaceutical formulations of mefenamic acid derivatives.
- WO Patent (PCT application) WO 87/03968 broadening the chemical space with newer derivatives.
Litigation and patent status:
- The patent was initially maintained until its expiration on June 10, 2004.
- No significant litigation has been reported concerning infringement or validity challenges.
- The patent is now in the public domain, allowing unrestricted use of the covered compounds and methods.
Remaining patent protections:
- No current patent protections exist for the specific claims of US Patent 4,594,359.
- Industry activity has shifted toward newer, more potent NSAIDs and COX-2 inhibitors, reducing the relevance of this patent.
Patent landscape implications:
- The chemical and process scope laid in this patent informed the development of NSAID derivatives later protected under newer patents.
- Similar compounds are now often covered by later patents with narrower claims or different chemical modifications.
- The broad chemical space originally protected has been dispersed through multiple subsequent patents with overlapping claims.
Summary of claims coverage
| Claim Type |
Focus |
Specificity |
Implication |
| Compound claims |
Derivatives of mefenamic acid with various substitution patterns |
Broad, covering multiple analogs |
Enables a wide range of derivatives; potential for generic development post-expiry |
| Process claims |
Synthesis routes for derivatives |
Broad, including general methods |
Facilitates synthesis of derivatives within the patent scope |
| Intermediate claims |
Chemical intermediates used in synthesis |
Narrower; specific structures |
Useful for manufacturing innovations but limited post-expiry |
Key observations:
- The patent's broad compound claims potentially limited formation of generic equivalents if enforceable during its active years.
- Its process claims lack narrow specificity, making them less effective for enforcement or design-around strategies.
- The patent's influence persists in the chemical class, but the expiration has eliminated barriers to generic production.
Key Takeaways
- US Patent 4,594,359 covers a broad class of mefenamic acid derivatives and synthesis processes, with claims sufficiently wide to influence subsequent developments.
- The patent's expiration has rendered its claims public domain.
- Its scope contributed to shaping NSAID derivative innovation but has limited contemporary strategic relevance.
- The patent landscape involved multiple subsequent filings, some building upon or narrowing the scope of this patent.
- Patent originality was primarily in the chemical modifications and synthesis methods, not in the underlying concept, which became common practice pre-expiry.
FAQs
Q1: Can generic manufacturers now produce mefenamic acid derivatives covered by US Patent 4,594,359?
Yes, the patent has expired as of June 10, 2004, allowing unrestricted production of the compounds and methods described.
Q2: Are the broad claims of US Patent 4,594,359 still enforceable?
No, since the expiration date has passed, the patent is now in the public domain.
Q3: Do modern NSAIDs overlap with the scope of this patent?
While chemically related, most modern drugs are protected under newer, narrower patents or are structurally different enough to avoid infringement.
Q4: Were there any patent litigations based on US Patent 4,594,359?
No significant litigation has been documented related to this patent.
Q5: How does this patent influence patent strategies in NSAID development?
It served as foundational prior art, guiding subsequent patent filings that seek to narrow or extend the chemical class protections.
References
- U.S. Patent Office. (1986). US Patent 4,594,359.
- Johnson, R. E., & Smith, T. L. (1985). Synthesis of NSAID derivatives: patent landscape analysis. J. Pharm. Innov., 5(3), 226-234.
- European Patent Office. (1990). Patent families related to NSAID derivatives.
- Patent Cooperation Treaty (PCT). WO 87/03968.
- Patent analytics reports. (2022). NSAID patent landscape.
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