Scope and Claims of U.S. Patent 5,158,952
Patent Overview
U.S. Patent 5,158,952 was granted on October 27, 1992, to Warner-Lambert Company, covering a class of pharmaceutical compounds. It primarily claims a novel subclass of opioid analgesic compounds characterized by specific chemical structures and their pharmaceutically acceptable salts.
Major Claim Categories
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Compound claims:
The patent claims a series of compounds of a specified chemical formula, denoted as Formula I. These compounds are characterized by variations in substituent groups positioned at specific locations on a core molecule.
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Pharmaceutical compositions:
It claims pharmaceutical compositions containing the novel compounds combined with pharmaceutically acceptable carriers.
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Method of treatment:
The patent specifically claims the use of these compounds as analgesics, particularly for pain management, via administration to mammals.
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Salt and ester forms:
Claims extend to pharmaceutically acceptable salts and ester derivatives of the claimed compounds, broadening the scope of covered chemical entities.
Scope Details
- The patent broadly encompasses various substitutions at designated positions, including different alkyl groups, aryl groups, and cyclic structures.
- Claims are dependent on specific configurations, with some focusing on particular substituent combinations.
- The patent explicitly claims compounds with high affinity and selectivity for opioid receptors, providing potential for less addictive pain relief options.
- The methodology for manufacturing includes chemical synthesis routes adaptable to various substituents, enabling flexibility in production.
Claims Limitations
- Restrictions are explicitly on compounds within the specified chemical formula and their salts/esters.
- The "use" claims are limited to pain relief, with no indication of broader medical applications.
- The patent does not claim the entire chemical class but rather a defined subset based on the chemical formula.
Patent Landscape of U.S. Patent 5,158,952
Historical Context & Related Patents
- Filed: 1989 (Serial No. 07/322,534)
- Expired: 2009, after a 17-year term following the 1992 grant
- It shares a patent family with related filings in other jurisdictions (e.g., EP, WO filings), indicating strategic international positioning.
Key Competitors and Follow-on Patents
- Several subsequent patents have cited or built upon the 952 patent, including:
- Formulation patents for specific dosage forms.
- Method patents targeting alternative therapeutic uses.
- New chemical entities with similar structures but modified substituents aimed at improved efficacy or reduced side effects.
- Major pharmaceutical companies such as Purdue Pharma and Endo Pharmaceuticals have filed related patents, particularly in the areas of pain management.
Patent Citations and Influences
Legal status
- The patent is expired, opening the field for generic manufacturing and research without licensing restrictions.
- As of 2023, the patent no longer confers exclusive rights, but research continues to build on the structures disclosed.
Patentability Constraints and Opportunities
- The chemical structure's narrow scope limits patentability of similar compounds unless novel modifications are introduced.
- The expiration allows for commercial development of generics or biosimilars based on the conserved structure.
Key Takeaways
- U.S. Patent 5,158,952 covers a specific subclass of opioid compounds intended for pain relief with claims extending to derivatives, compositions, and use methods.
- The patent's scope is primarily chemical, focusing on compounds with particular substitutions within a broad chemical formula.
- It influenced subsequent patent filings, especially in formulations and method claims, but is now expired, providing open pathways for research and generic production.
FAQs
1. What chemical class does U.S. Patent 5,158,952 belong to?
It claims a subclass of opioid analgesic compounds, focusing on certain chemical structures with specific substitutions.
2. How broad are the claims regarding chemical derivatives?
Claims include specific compounds within the defined chemical formula, along with pharmaceutically acceptable salts and esters, but do not encompass the entire chemical class.
3. Who were the patent assignees, and what was their strategy?
Warner-Lambert held the patent, aiming to control a specific subclass of opioids for pain management, with subsequent filings exploring formulations and treatment methods.
4. Has this patent been cited in subsequent patents?
Yes. It has been referenced in numerous later patents related to opioids, formulations, and alternative therapeutic uses.
5. Can generic companies now produce drugs based on these compounds?
Yes. Since the patent expired in 2009, generic manufacturers can produce drugs based on the compounds covered without infringing patent rights.
References
- U.S. Patent 5,158,952 (filed 1989, issued 1992).
