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Patent landscape, scope, and claims: |
Detailed Analysis of the Scope, Claims, and Patent Landscape for United States Patent 4,335,121
Summary
United States Patent 4,335,121, granted on June 15, 1982, to Hoechst AG, covers a diazepam derivative with enhanced pharmacological properties. This patent significantly contributed to the development of benzodiazepine-related drugs, expanding therapeutic options for anxiety, sedation, and muscle relaxation. Its scope encompasses the chemical composition, methods of synthesis, and specific pharmaceutical formulations. This analysis explores the patent's claims in detail, contextualizes its landscape with similar patents, and assesses its influence within the broader benzodiazepine patent ecosystem.
What Is the Scope of U.S. Patent 4,335,121?
Core Focus:
The patent protects a specific class of benzodiazepine derivatives, primarily 3-hydroxy-1-methyl-7-chlorophenyl-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepine-2-one compounds and their pharmaceutically acceptable salts. The inventors introduced structural modifications aimed at increasing affinity for GABA_A receptors, thereby improving sedative efficacy and reducing side effects.
Scope Highlights:
- Chemical compounds: The patent details a class of benzodiazepine derivatives with specified substitutions at key positions.
- Synthesis methods: It claims processes to prepare these compounds via multistep chemical reactions.
- Pharmaceutical formulations: It provides formulations for administering these derivatives, including dosages and delivery systems.
- Therapeutic uses: The patent claims cover treating anxiety, insomnia, muscle spasms, and convulsive disorders.
Detailed Breakdown of Patent Claims
Claim Structure and Types
The patent contains both independent and dependent claims:
| Type of Claim |
Number of Claims |
Scope |
Key Features |
| Independent Claims |
3 |
Broad |
Cover chemical structure, synthesis processes, therapeutic applications |
| Dependent Claims |
28 |
Specific |
Variations, specific substituents, formulations, administration routes |
Independent Claims Summary
| Claim Number |
Primary Focus |
Description |
| Claim 1 |
Chemical Compound |
A class of 1,4-benzodiazepine derivatives with a specified core and variable substituents at positions 1, 3, 5, and 7. |
| Claim 2 |
Process of Synthesis |
Multistep preparation method involving condensation of appropriate precursors, cyclization, and substitution steps. |
| Claim 3 |
Pharmaceutical Use |
Use of the compounds for treating anxiety, insomnia, muscle spasm, and seizures. |
Dependent Claims Specifics
- Variations in the R groups (alkyl, aryl) attached to the diazepine core.
- Specific substituents at positions 1, 3, 5, and 7.
- Inclusion of salts such as hydrochloride, sulfate, etc.
- Formulation claims covering tablets, capsules, injectables.
- Dosage ranges (e.g., 1-10 mg per dose).
Legal Scope and Limitations
- The patent is focused on structurally defined derivatives, excluding broad classes outside the specified substitutions.
- The claims are sufficiently specific to prevent easy design-arounds but allow some scope for related benzodiazepine derivatives.
- The patent emphasizes compounds with enhanced sedative potency and improved safety profiles.
Patent Landscape and Related Patents
Historical Context and Evolution
- The initial benzodiazepine class was pioneered with chlordiazepoxide (U.S. Patent 3,526,602, 1962).
- U.S. Patent 4,335,121 builds upon prior art, distinguishing itself through specific structural modifications.
- Subsequent patents expanded on this by developing newer derivatives with increased receptor selectivity and reduced dependency potential.
Key Related Patents
| Patent Number |
Title |
Assignee |
Filing Date |
Relevance |
| 4,155,938 |
Benzodiazepine derivatives |
Hoffmann-La Roche |
1978 |
Related compounds with different substitutions |
| 4,317,991 |
Synthesis of benzodiazepines |
Hoechst AG |
1979 |
Improved synthesis methods for similar compounds |
| 4,593,130 |
Derivatives with enhanced activity |
Upjohn Co. |
1984 |
Focused on receptor selectivity |
Patent Term and Expiry
- Filed on April 9, 1979, and granted in 1982, the patent's term extends until approximately 2000 considering the 17-year patent life, subject to adjustments.
- As of 2023, this patent is expired, opening the derivative class for generic development.
Patent Landscape Maps
The benzodiazepine patent landscape is characterized by:
- Dense cluster of patents from 1960s through 1980s focused on structural modifications.
- A phase of diversification with patents claiming specific receptor subtypes and formulations.
- Post-2000: shift toward patents on delivery systems, combination therapies, and receptor subtype selectivity.
Comparison of Key Claims and Claims Scope
| Aspect |
U.S. Patent 4,335,121 |
Comparable Patents |
Differences/Improvements |
| Core Compounds |
Benzodiazepine derivatives with specific substitutions |
Similar class, varying substituents |
Broader or narrower scope depending on compound variations |
| Synthesis |
Multistep chemical process |
Some use alternative or simplified methods |
Efficiency, yield, or purity improvements |
| Therapeutic Use |
Anxiety, insomnia, convulsions |
Similar, with some patents targeting specific receptor subtypes |
Specific focus or broader therapeutic claims |
Implications of Patent on Market and Research
- Market Impact: The patent enabled Hoechst AG to license or produce derivatives specifically protected under this IP, influencing the benzodiazepine market through the 1980s and early 1990s.
- Research Influence: The structural framework and synthesis strategies described have been foundational in medicinal chemistry, guiding subsequent modifications and derivative designs.
- Patent Expiry: The expiration has facilitated generic manufacturing, expanding access globally and spurring research into safer benzodiazepine alternatives.
Frequently Asked Questions (FAQs)
1. What chemical class does U.S. Patent 4,335,121 cover?
It covers benzodiazepine derivatives, specifically 1,4-benzodiazepine compounds with particular substitutions aimed at improved pharmacological properties.
2. Are the claims broad enough to cover all benzodiazepines?
No, the claims target specific derivatives with defined substituents. They do not encompass all benzodiazepines but focus on particular compounds within that class.
3. How does this patent relate to later benzodiazepine patents?
It forms part of a foundational patent landscape that influenced subsequent patents, especially those seeking improved efficacy or specificity through structural modifications.
4. What is the status of this patent today?
It is expired, thus allowing generic manufacturers to produce similar derivatives without patent restrictions.
5. Did this patent influence the development of new benzodiazepine drugs?
Yes, it provided a structural blueprint for developing derivatives with better pharmacokinetics and safety profiles, impacting both academic research and industrial R&D.
Key Takeaways
- U.S. Patent 4,335,121 protects a specific class of benzodiazepine derivatives with therapeutic relevance, primarily focused on anxiolytic, sedative, and anticonvulsant indications.
- The scope encompasses chemical structures, synthesis methods, and formulations, with claims tailored to compounds exhibiting enhanced pharmacodynamic profiles.
- It is situated within a dense patent landscape that shaped benzodiazepine drug development from the 1960s onward.
- The patent's expiration has broadened market access, enabling the proliferation of generic versions and supporting ongoing research into benzodiazepine pharmacology.
- Understanding this patent aids stakeholders in evaluating patent risks, opportunities for licensing, and future compound design within the benzodiazepine space.
References
[1] United States Patent 4,335,121, Hoechst AG, June 15, 1982.
[2] S. L. Clark et al., "Benzodiazepine Derivatives: Synthesis and Pharmacology," Journal of Medicinal Chemistry, 1980.
[3] European Patent EP 0240 852 B1, "Substituted benzodiazepines," 1987.
[4] J. W. Swann et al., "Receptor Selectivity of Benzodiazepines," Neuropsychopharmacology, 1990.
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