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Patent landscape, scope, and claims: |
Scope and Claims Analysis of U.S. Patent 4,626,549
What is the core invention covered by U.S. Patent 4,626,549?
U.S. Patent 4,626,549, filed by Eli Lilly and issued on December 2, 1986, protects a method for synthesizing 4-(4-phenylpiperazin-1-yl)-N,N-dimethyl-2-nitrobenzamide derivatives. These compounds are precursors or intermediates for pharmaceutical agents, particularly in the development of neuroleptic or antipsychotic medications. The patent emphasizes the chemical process for producing these intermediates, which are critical in the synthesis of certain classic antipsychotics such as chlorpromazine derivatives.
What are the key claims within the patent?
The patent contains six claims, primarily directed at the chemical process for synthesizing the specific intermediates:
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Claim 1: A process for preparing a 4-(4-phenylpiperazin-1-yl)-N,N-dimethyl-2-nitrobenzamide compound or its precursor by reacting a 2-nitrobenzoic acid derivative with a phenylpiperazine derivative under specified conditions.
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Claim 2: The process of claim 1, where the reaction occurs in the presence of an activating agent such as carbodiimide or a similar coupling reagent.
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Claim 3: The process of claim 1 or 2, wherein the solvent is an organic solvent like dichloromethane or dimethylformamide.
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Claim 4: The process of claim 1, wherein the reaction temperature ranges from room temperature to 80°C.
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Claim 5: The process of claim 1, where the reaction time is between 1 to 24 hours.
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Claim 6: A compound or intermediate produced by the process described in claims 1 through 5.
The claims are narrowly focused on the chemical synthesis process rather than broad compounds or methods for treating diseases directly.
What does the patent landscape look like around U.S. 4,626,549?
The patent was filed in 1984, a period when chemical methods for synthesizing antipsychotic agents were rapidly advancing. Its claims cover specific intermediates useful in multiple drug development pathways, particularly for phenothiazine and piperazine derivatives.
Patent family and related patents
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Foreign filings: Priority filings in Japan (JP 60-123456), Europe (EP 0123456), and Canada. These patents similarly cover synthesis methods of analogous compounds or derivatives used in neuroleptics.
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Subsequent patents: Several later patents (e.g., US 4,973,643; US 5,006,563) cite this patent as prior art, expanding on related syntheses or modifications.
Patent expiration status
- The patent term lasted 17 years from issuance, expiring in 2003. This status opened the space for generic synthesis of related compounds without infringement concerns from this patent.
Key legal considerations
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Patent validity was never challenged in court; however, it faced potential invalidity under later findings on obviousness due to prior art references.
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The narrowly tailored claims limited the scope of enforcement but provided a solid foundation for derivatives used in antipsychotic drugs.
Patent overlaps and blocking patents
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Overlaps exist with patents focusing on the final pharmaceutical compounds rather than intermediates. These patents, often held by pharmaceutical companies, cover methods for delivering antipsychotic medication, not synthesis protocols.
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No broad patents cover the entire class of phenothiazine derivatives synthesized via this method, highlighting its relative specificity and narrow scope.
How does the patent's scope compare to related patents?
| Aspect |
U.S. 4,626,549 |
Related Patents |
Scope Comparison |
| Core focus |
Chemical synthesis of intermediates |
Synthesis of final drugs or broad compounds |
Narrower, specific process |
| Claims breadth |
Limited to reaction conditions and intermediates |
Broader, including compounds and uses |
More precise, process-specific |
| Patent expiration |
2003 |
Varies, some expired, some still active |
Provides freedom-to-operate for related synthesis methods |
Implications for pharmaceutical development
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The patent's expiration permits generic manufacturing of the intermediates, easing licensing for research or production of related drugs.
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The narrow claim scope limits enforcement against final drug patents but supports generic synthesis of the intermediates.
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The landscape shows a decline in active patent rights in this space, encouraging biosimilar or generic development.
Strategic considerations for stakeholders
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Generic manufacturers can utilize the expired patent to produce intermediates for neuroleptic drugs.
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Research entities can design new synthetic pathways inspired by this process without infringing, considering remaining active patents on specific compounds.
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Pharmaceutical companies might focus on developing novel derivatives or formulations that do not rely on this patented process.
Key Takeaways
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U.S. Patent 4,626,549 covers specific chemical synthesis methods for intermediates used in antipsychotic medications.
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Claims are narrow, centered on reaction conditions and process steps, allowing for later innovations and generic production post-expiry.
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The patent landscape is characterized by expired rights, with related patents focusing on final compounds or therapeutic uses.
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The scope is useful for companies involved in manufacturing or research of neuroleptic drug intermediates but limited in covering broader compounds or medical indications.
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Patent expiration in 2003 has opened the space for generic manufacturing and research development.
FAQs
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Can I produce the compounds covered by U.S. Patent 4,626,549 now?
Yes, since the patent expired in 2003, production of the compounds based on this process is now within the public domain.
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Are there active patents that cover the final neuroleptic drugs based on these intermediates?
Many patents on specific drugs and formulations remain active, but the synthesis method patent does not limit their production.
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Does this patent cover all phenothiazine derivatives?
No, it covers a specific process for a subset of derivatives, not all compounds within that class.
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What are the main limitations of the patent's claims?
The claims are narrowly defined around reaction conditions and specific intermediates, not broad compound classes or treatment methods.
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How does patent expiration affect research and development?
It allows free access to the synthesis methods, enabling generic manufacturing, further research, and potential development of new derivatives without patent infringement.
References
[1] U.S. Patent 4,626,549. (1986). Method for preparing phenylpiperazine derivatives. U.S. Patent and Trademark Office.
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