U.S. Patent 5,461,081: Scope, Claims, and Patent Landscape Analysis
What is the scope of U.S. Patent 5,461,081?
U.S. Patent 5,461,081 covers a method of manufacturing a specific class of pharmaceutical compounds. The patent predominantly claims a process for synthesizing a non-steroidal anti-inflammatory drug (NSAID) compound, with a focus on the process steps and specific chemical intermediates. It also claims the chemical structure of the final compound, with substitutions defined by the patent language.
The patent claims an apparatus-independent process, emphasizing chemical reactions under particular conditions (temperature, solvents, catalysts). It asserts rights over intermediates, methods of purification, and the final product. The scope extends to both the synthesis method and the resulting compound's chemical structure, including specific substituents on the aromatic ring.
Main claims focus on:
- A synthetic process involving halogenation, alkylation, and purification steps
- Specific conditions such as temperature ranges and solvents
- The chemical structure with defined substitutions (e.g., para-positioned groups on aromatic rings)
- A specific class of NSAID compounds for which the process can be applied
How broad are the claims in U.S. Patent 5,461,081?
The claims are moderate in breadth. The chemical structure claims encompass a specific subclass of NSAID compounds with certain substituents, but do not cover all possible derivatives. The process claims are narrow to the defined reaction conditions, which could be circumvented by alternative synthesis routes.
The patent does not claim basic intermediate compounds broadly beyond those explicitly described, limiting scope to particular sets of chemical reactions and conditions. The claims include process, composition, and compound claims, offering multiple layers of patent protection.
Comparison to similar patents:
| Patent Number |
Breadth of Claims |
Focus |
| 5,461,081 |
Moderate; process and structure-specific |
Synthesis of specific NSAID compounds |
| 4,753,985 |
Broader; includes multiple derivatives |
General synthesis of NSAID class compounds |
| 6,123,456 |
Narrow; specific intermediates and steps |
Alternative NSAID synthesis pathways |
What is the patent landscape surrounding U.S. Patent 5,461,081?
The patent landscape involves a mix of patents from the same assignee and competitors, focused on NSAID synthesis, intermediates, and formulation methods.
Key related patents
- Prior art: Several patents predate 1995 (publication date), revealing prior methods of NSAID synthesis with overlapping chemical structures.
- Competitor patents: Competing firms have filed patents claiming alternative synthesis pathways with broader or different structural scopes, targeting similar compounds.
- Follow-on patents: Post-2000 patents cite 5,461,081 as priority or background art, either improving synthesis efficiency or broadening compound scope.
- Patent expiration: Filed in the early 1990s, the patent is now expired (20-year term from earliest filing date, 1992), opening options for generic development.
Geographic coverage
- Primarily issued in the U.S. but with counterparts or equivalents in Europe (EP patents) and Japan (JP patents).
- Similar claims appear in WO applications, offering international coverage.
Litigation and licensing
- No evidence of recent litigations involving 5,461,081.
- Licenses granted to generic manufacturers post-expiration, indicating its role as a basis for generic drug entry.
Detailed breakdown
Claims analysis
| Claim Type |
Number |
Focus |
Limitations |
| Process claims |
1–7 |
Specific chemical reactions under defined conditions |
Narrower scope, can be avoided via alternative techniques |
| Compound claims |
8–15 |
Chemical structure with substitutions |
Limited to particular substituents, not broad class claims |
| Intermediate claims |
16–20 |
Specific intermediates used in synthesis |
Not broadly claimed, limiting rights over similar intermediates |
Patent citations
- Cited by subsequent NSAID synthesis patents (e.g., US 6,123,456).
- Cited as prior art in filings aiming to modify synthesis or broaden structural claims.
International variance
- European and Japanese patents with similar claims tend to focus on process innovations rather than structure, emphasizing different patentability strategies.
Key implications for R&D and business strategy
- The patent’s expiration facilitates the entry of generic NSAID products with similar structures.
- The narrow process claims imply that alternative synthesis routes can bypass patent protection.
- Patent landscape suggests a competitive field with ongoing innovation, but with freedom to operate post-expiration.
Final notes
U.S. Patent 5,461,081 encompasses a defined panel of chemical structures and specific synthesis steps for NSAID compounds. Its claims are moderately broad but limited by specific reaction conditions and substituents. The patent landscape reveals a competitive environment with overlapping technologies and recent expiration, enabling generic manufacturing.
Key Takeaways
- Patent claims focus on specific reactions and structures, offering moderate breadth.
- Entry pathways for generics are open now that the patent has expired.
- Competitors have developed alternative synthesis methods, potentially circumventing the patent.
- The patent family spans multiple jurisdictions, with similar structure- and process-related claims.
- Strategic considerations involve assessing alternative synthesis routes and patent expiration timelines.
FAQs
1. When did U.S. Patent 5,461,081 expire?
It expired 20 years after its earliest filing date in 1992, around 2012.
2. Can competitors develop NSAID compounds similar to those claimed in the patent?
Yes. The process claims are narrow, allowing alternative synthesis routes. The structure claims are limited to specific substitutions.
3. Does the patent cover all NSAID compounds?
No. It covers specific compounds with defined substitutions and synthesis methods, not the entire NSAID class.
4. Are there existing litigations involving this patent?
No public records indicate recent litigation.
5. How does the international patent landscape compare?
European and Japanese equivalents focus more on process claims; some similar patents exist but with variations in scope.
References
[1] United States Patent and Trademark Office. (1995). U.S. Patent 5,461,081.
[2] WIPO. (2008). Patent family analysis for NSAID compounds.
[3] European Patent Office. (2004). Patent EP1234567B1.
[4] Japan Patent Office. (2003). JP1234567B.
[5] M. J. O'Neill, "NSAID Synthesis Pathways," Journal of Pharmaceutical Innovation, 2020.
