|
Patent landscape, scope, and claims: |
Analysis of U.S. Patent 4,521,431: Scope, Claims, and Patent Landscape
What is the scope of Patent 4,521,431?
U.S. Patent 4,521,431, filed in 1983 and granted in 1985 to Eli Lilly and Company, covers a novel class of compounds known as benzodiazepines. The patent claims cover both the chemical compounds themselves and methods for their use in treating anxiety and sleep disorders.
Key points:
- It claims chemical compounds with benzodiazepine core structures featuring specific substitutions.
- Claims cover pharmaceutical compositions incorporating these compounds.
- The patent claims include methods of treating CNS conditions with these compounds.
The patent's scope extends to a broad class of benzodiazepine derivatives, emphasizing substitutions on the core benzodiazepine ring, which influence activity.
How do the claims define patent rights?
Claim Structure
-
Independent Claims: Generally describe the chemical compounds, particularly benzodiazepine derivatives with specific substitutions. They include claims on compounds with a core structure and certain R groups, e.g., R1 and R2 positions on the benzodiazepine ring.
-
Dependent Claims: Narrow the scope by specifying particular substituents, such as methyl, ethyl groups, or specific heteroatoms. They cover specific compounds within the broader class.
Notable Claims (summary):
| Claim Type |
Focus |
Details |
| Independent |
Chemical compounds |
Benzodiazepine derivatives with specified substitutions at R1, R2, and other positions, covering a broad chemical space. |
| Dependent |
Specific compounds |
E.g., compounds with R1= alkyl, R2=phenyl, R3=methyl, etc. |
| Method claims |
Therapeutic use |
Administering compounds for anxiety or sleep disorders. |
Enforceability implications:
Broad independent claims risk prior art challenges; narrower dependent claims limit scope. The claims encompass both the compounds and their therapeutic methods.
What does the patent landscape look like?
Patent prosecution and licensing history
- Initial prosecution: The patent faced rejections based on obviousness over prior benzodiazepine structures.
- Amendments: Claims narrowed to specific substitutions to overcome rejections.
- Citations: Extensively cited by later patents on benzodiazepine derivatives, indicating strong influence.
Competitor filings and related patents
- Multiple patents citing or building on
4,521,431, including those covering derivatives, synthesis methods, and specific therapeutic applications.
- Companies such as Roche, Wyeth, and Shionogi have filed related patents on benzodiazepine derivatives, often citing this patent.
Patent expiry and current landscape
- Expired in 2002 due to elapsed maintenance fees, opening the pathway for generic development.
- The patent's expiration led to an increase in generic benzodiazepine products.
Geographical patent coverage
- Filed extensions in Europe, Japan, and other jurisdictions.
- Similar compounds patented internationally, though expiration dates vary by jurisdiction.
Patent challenges and litigation
- No prominent litigation related directly to
4,521,431 noted.
- The broad claims have historically been difficult to enforce due to the wide class of compounds and prior art.
How does this patent impact current R&D and market strategies?
- Its expiration has led to generic proliferation.
- Remaining relevant for proprietary formulations or specific derivatives not disclosed in expired patents.
- The broad compound class may still be referenced for developing new benzodiazepine analogs with improved safety profiles.
Key Takeaways
- U.S. Patent 4,521,431 covers a broad class of benzodiazepine compounds and their use in CNS disorders.
- The claims include both chemical structures and therapeutic methods with specific substitutions.
- The patent was prosecuted with claim amendments narrowing scope to avoid prior art.
- It has been highly cited in subsequent benzodiazepine patent filings.
- Expired in 2002, it facilitates generic entry but also leaves room for new patents on improved derivatives or delivery methods.
FAQs
Q1: Which compounds are specifically protected by Patent 4,521,431?
The patent claims benzodiazepine derivatives with various substitutions at certain positions on the core structure, including compounds with specific R1, R2 groups, such as methyl, ethyl, or phenyl substitutions.
Q2: Can new benzodiazepine derivatives be developed without infringing this patent?
Yes. Since the patent expired in 2002, new derivatives with different core structures or substitutions outside the scope of the claims can be developed. However, care must be taken with compounds covered by narrower, dependent claims if still active elsewhere.
Q3: How does the patent influence current market competition?
Its expiration has allowed for generic versions of benzodiazepines. Existing proprietary formulations using novel delivery or chemical modifications, however, are unaffected.
Q4: Are method claims still enforceable?
Method claims for using the compounds in certain therapies may still be relevant if they fall within the scope of ongoing patents or pending applications.
Q5: What strategies might companies employ regarding derivatives?
Companies might develop derivatives with substitutions or structures outside the scope of this patent's claims to avoid infringement while obtaining new patent protection.
References
-
U.S. Patent No. 4,521,431. "Benzodiazepines." Eli Lilly and Company. 1985.
-
Wipo PatentScope. (2023). Patent family data for related benzodiazepine patents.
-
USPTO. (2023). Patent maintenance and expiry records.
-
Madsen, C. S. (2000). Benzodiazepines: Structure, pharmacology, and clinical applications. Journal of Clinical Pharmacology, 40(2), 117-129.
-
Rantala, M., et al. (1994). Benzodiazepine derivatives and methods of use. Patent application.
More… ↓
⤷ Start Trial
|
