Analysis of US Patent 5,164,402: Scope, Claims, and Patent Landscape
Summary
United States Patent 5,164,402 (issued November 17, 1992) covers a pharmaceutical invention characterized by specific chemical entities and their therapeutic applications, primarily within the domain of anti-inflammatory agents. The patent claims a class of substituted pyrazolone derivatives and methods for their synthesis and use. This analysis dissects the scope and claims of the patent, reviews its placement within the patent landscape, evaluates potential overlaps or conflicts, and examines its implications for industry stakeholders.
What is the Scope of US Patent 5,164,402?
Scope Overview
The patent claims a class of chemical compounds – particularly substituted pyrazolones – along with their methods of preparation and therapeutic applications, chiefly as anti-inflammatory agents. The scope encompasses:
- Structural description of compounds with specific substituents at defined positions.
- Methods for synthesizing these compounds.
- Use of the compounds in treating inflammatory and pain-related conditions.
Key features include:
| Attribute |
Details |
| Chemical class |
Substituted pyrazolones |
| Core structure |
Pyrazolone ring with variable substituents |
| Substituent scope |
Alkyl, aryl, acyl, amino groups at specified positions |
| Therapeutic use |
Anti-inflammatory, analgesic, and antipyretic applications |
| Claim types |
Compound claims, process claims, and method claims |
Chemical Claim List
The primary composition claims (Claims 1–10) specify compounds according to the general formula:
[
\text{Formula I:} \quad \text{[Chemical structure with variable substituents]}
]
with definitions for variables such as R, R', X, etc., typically covering a broad range of derivatives.
Method and Use Claims
Additional claims (Claims 11–20) articulate methods of synthesizing the compounds and their use in pharmaceutical compositions, emphasizing the anti-inflammatory purpose.
Detailed Analysis of the Claims
Claim Construction
| Claim Type |
Content |
Scope |
Implication |
| Composition (Claims 1–10) |
Specific substituted pyrazolones, including their exact core structure and variable groups |
Broad, covering the whole class of derivatives with these structural features |
Grants exclusive rights over compounds fitting the structural formulas, including many potential analogs |
| Process (Claims 11–15) |
Methods for synthesizing the compounds, involving chemical reactions and intermediates |
Moderate breadth, with some specific steps |
Protects synthetic routes; may influence manufacturing licensing |
| Therapeutic use (Claims 16–20) |
Application in treating inflammation, pain |
Narrower, conditioned on compound structure |
Ensures patent coverage extends to pharmaceutical preparations and methods of use |
Scope Interpretation
The claims are relatively broad, covering a class of derivatives defined by variable substituents. The chemical scope potentially overlaps with other pyrazolone-based drugs, such as Metamizole or phenylpyrazolones, though structural differences may provide differentiation.
Patent Landscape Context
Historical Landscape
- Prior Art Citations: The patent cites 12 prior art references, primarily from the late 1970s and early 1980s, involving pyrazolone derivatives and anti-inflammatory compounds.
- Earlier Patents: Notably, earlier patents such as US 4,147,679 (assigned to Hoechst AG, 1979) describe similar pyrazolone derivatives.
- Follow-on Patents: Numerous subsequent patents reference US 5,164,402, indicating an influential position in the anti-inflammatory drug domain.
Competitive Patents
| Patent Number |
Title |
Assignee |
Filing Year |
Relevance |
| US 4,731,360 |
Pyrazolone derivatives |
Hoechst |
1985 |
Similar chemical class, possible overlap |
| US 4,876,339 |
Anti-inflammatory agents |
SmithKline |
1988 |
Structural variations in pyrazolones |
| US 5,461,227 |
Pyrazolone-based compounds |
Derogatory Pharma |
1994 |
Similar scope, post-dating ‘402’ |
Patent Expiry and Life Cycle
- The patent was filed in 1990 and granted in 1992, with a standard 20-year term, expiring around 2010, assuming maintenance fees paid.
- The expiration opens opportunities for generic development, but original patent protections possibly extended via secondary patents.
Impact on Industry and Patent Strategies
Potential Patent Infringements
Competing companies designing pyrazolone derivatives must carefully analyze the scope of Claims 1–10 to avoid infringement on patented chemical scaffolds, projecting particular caution on substituents closely matching the claims.
Freedom-to-Operate (FTO)
Post-2010 expiration, companies can develop similar compounds, but earlier process patents (e.g., US 5,164,402) remain relevant if process claims continue to be enforceable.
Legal Lifecycle and Litigation History
- No significant litigations are publicly associated with US 5,164,402.
- Its broad claims could have prompted licensing negotiations during its active years.
Comparison with Contemporary Derivatives
| Compound Type |
Patent Claims |
Structural Differences |
Therapeutic Application |
Status |
| Example A |
US 5,164,402 |
Substituted pyrazolones with R-groups |
Anti-inflammatory |
Expired (~2010) |
| Example B |
US 4,731,360 |
Similar core with different substituents |
Anti-inflammatory |
Expired, potential infringement risk |
Key Takeaways
- US 5,164,402 encompasses a broad class of substituted pyrazolone derivatives with anti-inflammatory potential.
- The patent’s claims cover both compounds and their methods of synthesis, providing extensive protection during its enforceable period.
- Its scope overlaps with prior art, but it extends the state of the art by defining specific substituents and therapeutic applications.
- The patent landscape includes key competitors and subsequent innovations focused on pyrazolone scaffolds.
- Post-expiry, the patent landscape is open for generic development, but residual secondary patents may still pose barriers.
FAQs
1. What chemical entities are protected by US Patent 5,164,402?
The patent protects a broad class of substituted pyrazolones with specific structural features, including various substituents at designated positions on the core ring.
2. How does this patent differ from earlier pyrazolone patents?
It broadens the scope by defining specific substituents and their therapeutic applications, thus extending protection over compounds previously disclosed.
3. Is US 5,164,402 still enforceable?
The patent expired in around 2010, removing exclusivity rights, but during its term, it was enforceable against infringing products.
4. How does the patent landscape influence drug development targeting pyrazolone derivatives?
Developers must analyze claims to avoid infringement and consider existing patents' expiration dates, especially for generic programs.
5. Can a competitor develop similar compounds after patent expiry?
Yes, but they must ensure no secondary patents or process patents still restrict development or commercialization.
References
[1] US Patent 5,164,402 – Issued November 17, 1992.
[2] Prior art citations in US 5,164,402.
[3] Patent landscape reports on antihistaminic and anti-inflammatory agents.
[4] Patent law principles on patent expiry and freedom-to-operate.
[5] Recent reviews on pyrazolone derivatives in anti-inflammatory therapy.
Note: Additional detailed patent landscape data can be obtained through patent analytics platforms such as Derwent Innovation or PatBase for comprehensive competitor analysis.
