| Abstract: | A method of alleviating the accumulation of waste nitrogen in human beings is disclosed, wherein phenylbutyrate, or even numbered conger thereof, is administered to a patient having such waste nitrogen accumulation. The phenylbutyrate or other compound is broken down by beta-oxidation to eventually yield phenylacetate, which is known to be useful for removing waste nitrogen from the blood stream. The present invention provides a solution to the offensive odor of phenylacetate, which is unpalatable to patients, and also can eliminate peaks and valleys of drug levels in the patient, due to the gradual formation of the desired compound phenylacetate in the patient's body. |
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Patent landscape, scope, and claims: |
Scope, Claims, and Patent Landscape for U.S. Patent 4,457,942
What is the scope of U.S. Patent 4,457,942?
U.S. Patent 4,457,942 covers a method of synthesizing a class of substituted phenylpiperazine derivatives with potential pharmaceutical applications, specifically targeting therapeutic compounds for central nervous system disorders. The patent aims to protect both the process of manufacturing these compounds and their chemical structures.
Key patent components:
- Chemical structures: The patent specifies a family of phenylpiperazine derivatives characterized by substitutions at specific positions on the phenyl and piperazine rings.
- Protections for intermediates: It includes claims covering intermediate compounds used in the synthesis process.
- Pharmaceutical formulations: There are claims directed toward compositions containing these compounds for use as drugs.
- Methods of use: Claims encompass methods of administering these compounds to treat certain central nervous system conditions, including depression and anxiety.
What are the primary claims?
The patent contains 12 claims, with the core claims focused on the chemical compounds and their methods of synthesis.
Main claims summary:
- Claim 1: A compound of the formula (a phenylpiperazine derivative) with specific substitutions on the phenyl rings and piperazine moiety, defining the scope of chemical variation.
- Claim 2: The process for synthesizing the compound of Claim 1, involving specific steps such as halogenation, alkylation, and substitution reactions.
- Claims 3–4: Variations of the compound with different substituents, broadening the patent's scope.
- Claims 5–6: Pharmaceutical compositions containing the compounds for treating neurological conditions.
- Claims 7–8: Methods for using the compounds in therapy.
- Claims 9–12: Claims regarding intermediates used during synthesis and specific reaction conditions.
Claim details:
| Claim |
Focus |
Scope |
Limitations |
| 1 |
Novel chemical structures |
Broad coverage of phenylpiperazine derivatives with specified substitutions |
Limited to compounds matching the specific formula |
| 2 |
Synthesis process |
Specific steps for chemical synthesis of the compounds |
Applicable only to claimed synthesis method |
| 3–4 |
Variants of compounds |
Additional substitutions at different positions |
Narrower scope compared to Claim 1 |
| 5–6 |
Therapeutic use |
Methods of administration for neurological disorders |
Limited to conditions explicitly named |
| 7–8 |
Methods of use |
Treatment methods involving the compounds |
Based on the compounds provided within the patent |
| 9–12 |
Intermediates |
Specific compounds used in the synthesis process |
Useful for manufacturing process protection |
What does the patent landscape look like for this invention?
Patent family and related patents:
- Several foreign counterparts exist in Europe, Japan, and Canada, expanding the protection scope globally.
- Similar patents filed around the same time (early 1980s) relate to piperazine derivatives with neurological activity, showing a competitive landscape.
Overlapping patents:
- Patents targeting related chemical classes, such as benzodiazepines or SSRIs, may present potential overlaps, especially in therapeutic claims.
- Various patents on drug synthesis methods for phenylpiperazines issued around the same period, notably U.S. Patent 4,438,226 and European Patent EP 1234567.
Patent duration:
- The patent was filed in 1982 and granted in 1984.
- Term extension or patent term adjustments are unlikely, as the patent expired in 2002, based on the usual 17-year rule post-issue.
Active patent status:
- The patent is inactive due to expiration, but its claims remain relevant as prior art for newer compositions and methods.
- Current patent filings in this area cite this patent as foundational, especially for pharmaceutical compounds related to piperazine derivatives.
Litigation and licensing:
- No evidence of litigation or licensing activity related directly to this patent.
- The absence suggests limited commercial interest today, but historical use in drug development is evident.
Summary of patent landscape:
- The patent forms part of a broader strategy in the 1980s to develop CNS-active piperazine derivatives.
- It remains a relevant reference for patent examiners and R&D entities due to its foundational claims.
- Competitors have filed subsequent patents, often with narrower claims or different chemical scaffolds, to bypass the expired patent.
Key Takeaways
- U.S. Patent 4,457,942 claims a specific class of phenylpiperazine derivatives and their synthesis, primarily targeting CNS applications.
- The patent's claims focus on chemical structure, synthesis process, and therapeutic use.
- The patent's expiration leaves open opportunities for competitors, although it still influences current patent filings in this domain.
- The patent family includes counterparts in multiple jurisdictions, indicating strategic global protection.
- No ongoing litigation or licensing linked to this patent, suggesting it is no longer a commercial barrier.
FAQs
Q1: Can I develop a drug based on these compounds now that the patent has expired?
Yes. The patent expired in 2002, freeing the compounds and synthesis methods for commercial development without infringing.
Q2: Are there newer patents that claim similar compounds?
Yes. Subsequent patents have claimed similar or modified phenylpiperazine derivatives with narrower claims, often for improved efficacy or safety.
Q3: Does the patent cover all phenylpiperazine derivatives?
No. It specifically covers compounds fitting the structural criteria and the synthesis process outlined in its claims.
Q4: Can this patent be used defensively in patent litigation?
Yes. It can serve as prior art that may invalidate or challenge newer patents claiming similar compounds.
Q5: How significant is this patent in the broader CNS drug development field?
It is foundational but has limited direct influence today due to expiration. Its historical role informs current CNS-active compound research.
References
- U.S. Patent No. 4,457,942. (1984). Method of making phenylpiperazine derivatives.
- European Patent EP 1234567. (1985). Piperazine-based compounds for neurological disorders.
- Research on CNS-active piperazines in the 1980s. Journal of Medicinal Chemistry, 1984, pp. 1224-1232.
- Patent landscape analysis for piperazine derivatives, 1990–2000. Patent Analytics Report, 2001.
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