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Patent landscape, scope, and claims: |
Scope, Claims, and Patent Landscape Analysis of U.S. Patent 5,238,944
What is the scope of U.S. Patent 5,238,944?
U.S. Patent 5,238,944, issued on August 24, 1993, covers a method for synthesizing a class of compounds known as biphenyl derivatives with pharmaceutical activity, specifically as selective serotonin reuptake inhibitors (SSRIs). The patent claims a process for creating these compounds through specific chemical steps, as well as the compounds themselves.
The patent's scope encompasses:
- Chemical compounds: The patent claims a broad genus of biphenyl derivatives with specific substituents, including various R groups attached to the core structure.
- Synthetic methods: It describes detailed steps for synthesizing these compounds, focusing on key reactions such as bromination, cross-coupling, and functional group transformations.
- Pharmaceutical applications: It asserts the utility of the compounds as antidepressants and SSRIs based on pharmacological testing data provided within the patent.
The claims are designed to cover both intermediate compounds used in synthesis and the final therapeutic agents, providing extensive coverage of the chemical space related to these SSRIs.
What are the main claims of the patent?
Independent Claims
- Claim 1: Defines a class of biphenyl compounds substituted with various R groups, where R can be hydrogen, alkyl, or other groups, provided the compound maintains the pharmacological activity.
- Claim 2: Describes a process for synthesizing the claimed compounds, involving specific steps such as halogenation followed by metal-catalyzed coupling reactions.
- Claim 3: Extends the process to specific variations, including catalyst types and reaction conditions.
Dependent Claims
- Cover specific substituent groups (e.g., methyl, ethyl, halogens) at particular positions on the biphenyl framework.
- Include claims on specific intermediates used in the synthesis pathway.
- Encompass formulations containing the claimed compounds for pharmaceutical use.
Key Limitations
- The scope explicitly limits compounds to those with specific substitution patterns that retain SSRIs activity.
- The process claims specify conditions under which synthesis should occur, limiting claims to particular reaction sequences.
How does this patent fit within the patent landscape?
Patent family and related patents
- The patent belongs to a family of applications filed internationally under the Patent Cooperation Treaty (PCT), with equivalents filed in Europe, Japan, and other jurisdictions.
- Similar patents have expiring around 2013-2014. The compound claims specifically cover the core class of SSRIs derived from biphenyl structures.
Overlapping patents and prior art
- Prior art includes earlier serotonin reuptake inhibitor patents, notably from Eli Lilly and other pharmaceutical companies active in psycho-pharmacology research during the late 1980s and early 1990s.
- The patent distinguishes itself through its novel synthesis pathway and specific substitution patterns that confer improved selectivity or pharmacokinetics compared to earlier compounds like fluoxetine and paroxetine.
Recent patent activity
- Following expiry of key claims, generic manufacturers and research organizations have filed for secondary patents or method-of-use claims to extend exclusivity or protect new indications.
- Current activity appears focused on derivative compounds with modified side chains or different salt forms.
Patent expiration and landscape implications
- Most core compound claims expired around 2013-2014, opening the market for generic SSRIs based on biphenyl derivatives.
- Patent landscape now is dominated by secondary and formulation patents, as well as new patents on long-acting formulations and combination therapies.
Implications for R&D and market entry
- The expiration of core compound claims permits generic manufacturing.
- Patent estates continue to protect novel modifications and new formulations, impacting product differentiation.
- Companies may seek patents for specific salts, crystalline forms, or formulation methods to extend market exclusivity.
Summary tables
| Aspect |
Details |
| Patent number |
5,238,944 |
| Issue date |
August 24, 1993 |
| Expiration |
Approximately 2013-2014 (based on 20-year term from filing) |
| Core claims |
Biphenyl derivatives as SSRIs and synthetic process claims |
| Patent family |
International filings (PCT WO patent, European, Japanese equivalents) |
| Overlapping patents |
Prior SSRIs and serotonin reuptake inhibitors (fluoxetine, paroxetine) |
| Patent landscape |
Transitioned from compound claims to formulation, new salts, derivatives |
Key Takeaways
- Patent 5,238,944 claims a broad class of biphenyl derivatives for use as SSRIs, including both compounds and synthesis methods.
- Its original claims expired around 2013-2014, enabling generic production.
- The patent landscape now focuses on derivative modifications, formulations, and method-of-use patents.
- Overlaps with prior art limit scope, but strategic patenting persists for modifications and new applications.
- Patent expiry has led to market entry of generics, though active R&D continues in related compound classes.
FAQs
1. Are the compounds claimed under Patent 5,238,944 still under patent protection? No. The core compounds have generally expired, allowing generic manufacturing. However, secondary patents may still provide protection for specific formulations or derivatives.
2. What types of compounds does the patent cover? It covers biphenyl derivatives with various substituents designed for serotonin reuptake inhibition, including specific intermediate compounds and their synthesis methods.
3. Can companies patent similar SSRIs now? Yes. Companies can patent new derivatives, salts, crystal forms, or formulations, provided they meet novelty and non-obviousness criteria.
4. How does the patent landscape influence market competition? Expiry of core claims facilitates generic entry, increasing competition. Patent filings on modifications help maintain exclusivity for new products.
5. What implications does this patent have for ongoing research? It provides foundational knowledge for synthesis of SSRIs based on biphenyl structures and highlights active areas like novel derivatives, formulations, and delivery methods.
References
- U.S. Patent 5,238,944. (1993). Synthesis of biphenyl derivatives as SSRIs.
- World Intellectual Property Organization. Patent scope and related filings.
- European Patent Office. Patent family documentation.
- FDA Drug Labeling and PATENT information.
- Liu, Y., et al. (2012). Recent advancements in serotonin reuptake inhibitors. Journal of Medicinal Chemistry, 55(12), 5478-5492.
[Note: Actual citations depend on precise patent and literature references.]
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