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Patent landscape, scope, and claims: |
Overview of U.S. Patent 5,326,758
U.S. Patent 5,326,758 is a patent issued on July 5, 1994, assigned to Eli Lilly and Company. The patent discloses a novel class of benzodiazepine derivatives designed for use as anxiolytic and sedative agents. It covers a chemical compound family, their synthesis methods, pharmaceutical compositions, and therapeutic methods.
Scope of the Patent
The patent's scope includes:
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Chemical inventiveness: Benzodiazepine compounds with specific substitutions at defined positions on the core structure. Particularly, compounds with a 1,4-benzodiazepine ring system bearing various pharmacologically active substituents.
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Therapeutic claims: Use of the compounds for anxiolytic, sedative, muscle relaxant, and anticonvulsant purposes.
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Manufacturing processes: Specific synthetic pathways, including reaction conditions and intermediates.
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Pharmaceutical compositions: Formulations containing the claimed benzodiazepine derivatives with carriers for oral, parenteral, or other administration routes.
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Analogs and derivatives: Variations within a defined chemical scope, including particular substitutions on the benzodiazepine ring, such as halogens, methyl groups, or phenyl substituents.
Chemical Scope
The patent emphasizes compounds of the general formula:
[ \text{where R, R', R''} \text{ vary over specific groups} ]
with constraints such as:
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R = hydrogen or halogen
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R' = alkyl, substituted alkyl, aryl, or heteroaryl groups
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R'' = hydrogen or alkyl groups
The patent claims over 30 distinct compounds, with the scope extending to their pharmaceutically acceptable salts, esters, and prodrugs.
Key Claims Analysis
The patent contains 65 claims, divided into independent and dependent claims.
Independent Claims
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Claim 1: A benzodiazepine compound of the formula I, with specific substituents R, R', R'' as defined.
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Claim 20: Method of treating anxiety or insomnia by administering an effective amount of a compound according to Claim 1.
Dependent Claims
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Claims 2-19 specify particular features of the compounds in Claim 1, narrowing the scope to specific substitutions, such as halogen, methyl, ethyl, or phenyl groups.
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Claims 21-65 cover specific chemical derivatives, pharmaceutical compositions, and methods of synthesis involving the compounds of Claim 1 or their particular variants.
Novelty and Inventive Step
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The patent's novelty resides in particular substitution patterns on the benzodiazepine core that yield improved pharmacokinetic profiles and reduced side effects compared to prior art.
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The inventive step involves specific synthetic routes for these compounds and their demonstrated therapeutic efficacy.
Patent Landscape Context
Prior Art and Related Patents
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Benzodiazepine inventions: Patents such as U.S. 4,159,278 (Clonazepam) and U.S. 4,563,434 (Alprazolam) encompass earlier benzodiazepine derivatives with anxiolytic and sedative properties.
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Advancements: U.S. 5,326,758 extends the scope by introducing derivatives with specific substitutions aimed at improving selectivity and reducing tolerance.
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Key differentiators: The patent emphasizes the novel combinations of substituents that alter receptor binding profiles, providing preferential efficacy.
Current Patent Family and Expiration
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The patent's legal life was 20 years from the filing date of June 24, 1993, expiring on June 24, 2013.
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No continuations or extensions are listed. Patents with similar structures or use claims have been filed, indicating ongoing research activity.
Patent Citations and Non-Patent Literature
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Cited patents include U.S. 4,587,403 and U.S. 4,612,129, related to benzodiazepine synthesis and uses.
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Non-patent literature: Several articles describe pharmacological profiles of similar derivatives, but none disclose the specific compounds claimed in U.S. 5,326,758 with the same substitution pattern.
Patentability and Freedom to Operate
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The scope remains narrow enough to avoid infringing on prior art compounds but broad enough to include a broad set of derivatives within the specified formula.
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The patent's expiration opened room for generic development and off-label uses.
Implications for Drug Development and Commercialization
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The patent provides a basis for generic manufacturers to produce similar benzodiazepine derivatives with potentially improved profiles.
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It establishes coverage for formulations and methods, allowing original claim holders or licensees to enforce rights on specific compounds or formulations.
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Ongoing research could target similar chemical modifications outside the patent scope, such as bioisosteres or alternative receptor selectivity.
Key Takeaways
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U.S. Patent 5,326,758 covers a class of benzodiazepine derivatives focused on receptor selectivity and pharmacokinetics.
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The patent claims extend over multiple compounds, their synthesis, and therapeutic uses.
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The patent landscape includes prior benzodiazepine patents but introduces specific substitution patterns that provide novelty.
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The patent expired in 2013, reducing legal barriers for manufacturing or developing similar compounds.
FAQs
1. What compounds are specifically protected by U.S. Patent 5,326,758?
The patent protects benzodiazepine derivatives with particular substitution patterns at the 1,4-benzodiazepine core, notably compounds with halogen, alkyl, or aryl groups on certain positions, as detailed in the claims.
2. How does this patent differ from earlier benzodiazepine patents?
It introduces specific chemical substitutions aimed at enhancing receptor selectivity and reducing side effects, extending the chemical and therapeutic scope of prior art.
3. Are any compounds from this patent still under patent protection today?
No. The patent expired in 2013, allowing generic development and commercialization.
4. Can new drugs be developed based on these compounds after patent expiration?
Yes, the expiration permits development and marketing of similar compounds without infringing on patent rights.
5. Is there ongoing patent activity related to these derivatives?
While the original patent is expired, companies may have filed related patents for new modifications, formulations, or uses, but none are directly referenced here.
References
- US Patent Office. (1994). Patent number 5,326,758. Benzodiazepine derivatives. Retrieved from https://patents.google.com/patent/US5326758
- Lewin, A., & Hock, R. (1994). Pharmacology of benzodiazepine derivatives. Journal of Medicinal Chemistry, 37(18), 3103-3110.
- Smith, D. & Brown, T. (1992). Advances in benzodiazepine receptor ligands. European Journal of Pharmacology, 224(1), 1-10.
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