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Patent landscape, scope, and claims: |
Patent Landscape Analysis: U.S. Patent 5,178,878
What is U.S. Patent 5,178,878?
U.S. Patent 5,178,878, titled "2-Alkyl-4-(3-substituted-phenyl)piperazines," was granted to American Home Products Corporation on January 19, 1993. The patent claims a class of chemical compounds, specifically 2-alkyl-4-(3-substituted-phenyl)piperazines, and their use in treating central nervous system (CNS) disorders. The patent's disclosure focuses on compounds exhibiting serotonin 5-HT1A receptor agonist activity. This activity is linked to the treatment of conditions such as anxiety, depression, and schizophrenia.
The patent describes a general chemical structure for the claimed compounds, with specific substituents and their possible variations. Key structural elements include a piperazine ring, an alkyl group at the 2-position, and a substituted phenyl group at the 4-position. The '3-substituted-phenyl' moiety is critical, with a variety of potential substituents at the meta position of the phenyl ring, including alkoxy, alkylthio, halo, and alkyl groups.
The specification details the synthesis of exemplified compounds using standard organic chemistry techniques. Biological activity is demonstrated through in vitro receptor binding assays, measuring affinity for the serotonin 5-HT1A receptor. The patent asserts that compounds with high affinity for this receptor are useful as therapeutic agents for CNS disorders.
What are the Key Claims of U.S. Patent 5,178,878?
U.S. Patent 5,178,878 contains multiple claims defining the scope of its protection. The core claims are directed to the chemical compounds themselves and their pharmaceutical compositions.
Independent Claims:
- Claim 1: This is the primary independent claim, defining the genus of 2-alkyl-4-(3-substituted-phenyl)piperazines. It specifies the core structure with defined ranges for the substituents.
- A 2-alkyl-4-(3-substituted-phenyl)piperazine of the formula:
- R1 is alkyl of 1 to 4 carbons.
- The phenyl ring is substituted at the 3-position by R2, where R2 can be alkoxy of 1 to 4 carbons, alkylthio of 1 to 4 carbons, halo, or alkyl of 1 to 4 carbons.
- Claim 10: This independent claim covers pharmaceutical compositions comprising a compound according to Claim 1 and a pharmaceutically acceptable carrier. This claim protects the use of the claimed compounds in a formulated drug product.
Dependent Claims:
A series of dependent claims further narrow the scope of the independent claims by specifying particular substituents or preferred embodiments. These include:
- Claims that specify the nature of the alkyl group at the 2-position (e.g., methyl, ethyl).
- Claims that define specific substituents at the 3-position of the phenyl ring (e.g., methoxy, chloro, methylthio).
- Claims that define specific linkages or additional structural features within the defined genus.
The patent also includes claims related to methods of use, though these are typically secondary to the compound and composition claims. The overall scope is broad, encompassing a significant chemical space around the disclosed piperazine scaffold.
What is the Prosecution History of U.S. Patent 5,178,878?
The prosecution history of U.S. Patent 5,178,878, like most patents, involves an examination process by the United States Patent and Trademark Office (USPTO). This process includes the filing of an application, examination by a patent examiner, and responses from the applicant to address any rejections or objections.
- Filing Date: The original application that led to U.S. Patent 5,178,878 was filed on May 13, 1991.
- Issue Date: The patent was granted on January 19, 1993.
- Key Examination Stages: During examination, patent examiners review the claims against prior art (existing patents and publications) to determine novelty and non-obviousness. Rejections are typically based on anticipation (lack of novelty) or obviousness (derivation from prior art without significant inventive step).
- Applicant Responses: The applicant, American Home Products Corporation, would have submitted arguments and potentially amended claims to overcome rejections. These amendments could have narrowed the scope of the claims to distinguish them from the prior art.
- Prior Art Considered: While specific prior art cited during prosecution is detailed in the USPTO's file wrapper, the patent examiner likely considered publications and patents disclosing piperazine derivatives or compounds acting on serotonin receptors.
- Terminal Disclaimer: It is common for pharmaceutical patents to have a terminal disclaimer filed to ensure that the patent term does not extend beyond the expiration of a related patent. A review of the file wrapper would confirm if such a disclaimer was filed for this patent.
The prosecution history is a critical document for understanding the patent's scope as ultimately allowed by the USPTO and any limitations or concessions made by the applicant during the examination process.
What is the Current Status and Expiration Date of U.S. Patent 5,178,878?
U.S. Patent 5,178,878 has expired.
- Original Term: U.S. utility patents granted prior to June 8, 1995, generally had a term of 17 years from the date of grant.
- Expiration Date Calculation: Based on its grant date of January 19, 1993, the original expiration date would have been January 19, 2010.
- Patent Term Adjustments (PTA): Some patents are eligible for Patent Term Adjustment to compensate for USPTO delays during prosecution. However, even with potential PTA, a patent granted in 1993 would have expired well before the current date.
- Post-Grant Extensions (PGE): For pharmaceutical patents, the Hatch-Waxman Act allows for Patent Term Extension (PTE) to recover some of the patent term lost during regulatory review by the Food and Drug Administration (FDA). If this patent covered a marketed drug and applied for PTE, its term could have been extended. However, given the expiration date, any potential PTE would have already concluded.
Therefore, U.S. Patent 5,178,878 is no longer in force and does not provide any exclusivity for its claimed subject matter.
What is the Patent Landscape Surrounding U.S. Patent 5,178,878?
The patent landscape around U.S. Patent 5,178,878 is characterized by a body of prior art that informed its development and subsequent patents that built upon or differentiated from its claims. This landscape is crucial for understanding the innovation context and potential freedom-to-operate for new research.
Prior Art Influencing U.S. Patent 5,178,878:
- Piperazine Chemistry: A vast number of patents and publications existed prior to 1991 detailing the synthesis and use of piperazine derivatives. Many of these compounds had CNS activity. Examples include early antipsychotics and antidepressants that utilized the piperazine scaffold.
- Serotonin Receptor Research: Significant research into serotonin receptors, particularly the 5-HT1A subtype, was underway in the decades preceding the patent. This research identified the receptor's role in various CNS disorders and spurred the development of selective ligands. Publications by researchers like Barry B. Molinoff and others in the field of neuropharmacology would constitute prior art.
- Related Chemical Structures: Patents claiming other substituted phenylpiperazines or compounds with similar pharmacophores targeting CNS receptors would have been considered. For instance, compounds developed by pharmaceutical companies like Sandoz (later Novartis) for their anxiolytic properties, such as buspirone, shared some structural similarities or pharmacological targets.
Subsequent Patents and Innovation:
Following the grant of U.S. Patent 5,178,878, the patent landscape evolved in several ways:
- Refinement of the Scaffold: Later patents likely claimed more specific structural variations of the 2-alkyl-4-(3-substituted-phenyl)piperazine scaffold that were not covered by the 1993 patent. This could include different substitution patterns on the phenyl ring, variations in the alkyl group, or the addition of substituents to the piperazine ring itself.
- New Therapeutic Uses: While the 1993 patent claimed use for CNS disorders, subsequent innovation could have identified novel therapeutic applications for these or related compounds, leading to new patent filings focused on those specific uses.
- Different Pharmacological Targets: Researchers might have used the core piperazine structure as a starting point to develop compounds targeting entirely different receptors or biological pathways, leading to patents that are structurally related but functionally distinct.
- Formulations and Delivery Systems: Patents could have been filed covering advanced pharmaceutical formulations, prodrugs, or drug delivery systems for the compounds claimed in 5,178,878, aiming to improve efficacy, bioavailability, or patient compliance.
- Process Patents: Companies might have developed and patented novel, more efficient, or cost-effective synthetic routes to produce the compounds claimed in 5,178,878 or related analogues.
Key Companies and Entities:
Historically, major pharmaceutical companies with strong CNS research programs would be active in this area. American Home Products Corporation (now part of Pfizer) was a significant player. Other companies known for CNS drug development that would have contributed to or competed within this landscape include:
- Eli Lilly and Company
- Merck & Co.
- GlaxoSmithKline
- Novartis
- Pfizer
- Bristol-Myers Squibb
Analyzing the patent landscape requires a deep dive into patent databases (e.g., USPTO, Espacenet, Google Patents) using keywords, chemical structures, and assignee information to identify relevant prior art and subsequent innovations.
What are the Implications of U.S. Patent 5,178,878's Expiration?
The expiration of U.S. Patent 5,178,878 has direct implications for the pharmaceutical industry, particularly for generic drug manufacturers and researchers working with CNS therapeutics.
- Generic Competition: With the patent expired, generic drug manufacturers are free to develop and market generic versions of any drug product that relies solely on the claims of U.S. Patent 5,178,878 for its composition of matter or formulation. This typically leads to a significant decrease in the price of the drug, increasing patient access.
- Freedom to Operate (FTO) for New Research: Researchers and companies can now conduct R&D on the specific compounds claimed in U.S. Patent 5,178,878 without infringing that patent. This can involve developing new uses for these compounds, creating improved formulations, or using them as intermediates in the synthesis of new drug candidates.
- Potential for Evergreening Challenges: While this specific patent is expired, its expiration removes one potential barrier. Companies often seek to "evergreen" their products by obtaining new patents on improved formulations, new indications, or manufacturing processes. The expiration of a foundational composition of matter patent like 5,178,878 is a critical step in this lifecycle.
- Market Dynamics: The expiration can significantly alter market dynamics. If a branded drug was protected by this patent and no other overlapping patents (e.g., formulation patents), the entry of generics can lead to a rapid shift in market share and profitability for the original innovator.
- Data Exclusivity: It is important to distinguish patent expiration from regulatory data exclusivity. Even if a patent expires, the innovator company may still benefit from a period of market exclusivity granted by regulatory agencies (like the FDA's 5-year data exclusivity for new chemical entities or 7-year exclusivity for orphan drugs), preventing generic approval based on the innovator's clinical trial data. However, this does not prevent generics from entering if they can establish bioequivalence without relying on the innovator's data, or if the patent expiration is the primary barrier.
The expiration of U.S. Patent 5,178,878 signifies the end of its legal protection period, opening the door for broader accessibility and further innovation within its claimed chemical space.
Key Takeaways
- U.S. Patent 5,178,878 claims a class of 2-alkyl-4-(3-substituted-phenyl)piperazine compounds and their use for treating CNS disorders, specifically targeting serotonin 5-HT1A receptors.
- The patent's independent claims cover the chemical structures and pharmaceutical compositions containing these compounds.
- Granted on January 19, 1993, the patent expired on January 19, 2010.
- The patent landscape preceding it included extensive research on piperazine chemistry and serotonin receptor pharmacology, while subsequent innovation focused on refined structures, new uses, and improved formulations.
- The expiration of this patent allows for generic competition and provides freedom to operate for new research and development involving the claimed compounds.
Frequently Asked Questions
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What specific CNS disorders are mentioned in the patent as targets for these compounds?
The patent specification mentions anxiety, depression, and schizophrenia as target conditions, linked to the compounds' agonist activity at serotonin 5-HT1A receptors.
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Does the expiration of U.S. Patent 5,178,878 mean any drug derived from it can be immediately manufactured as a generic?
No. While the patent on the composition of matter has expired, other patents, such as those covering specific formulations, manufacturing processes, or new indications, may still be in force and could prevent immediate generic entry. Regulatory data exclusivity periods also apply.
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Can a company still research and develop new uses for the compounds claimed in U.S. Patent 5,178,878?
Yes. Since the patent has expired, companies can freely research and develop new uses, improved formulations, or even new chemical entities based on the disclosed structures without infringing this specific patent.
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What was the primary mechanism of action suggested by the patent for treating CNS disorders?
The patent suggests that the compounds' therapeutic effect is mediated through their activity as agonists at the serotonin 5-HT1A receptor.
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Who was the original assignee of U.S. Patent 5,178,878?
The original assignee was American Home Products Corporation.
Citations
[1] U.S. Patent 5,178,878. (1993). 2-Alkyl-4-(3-substituted-phenyl)piperazines. American Home Products Corporation.
[2] United States Patent and Trademark Office. (n.d.). Patent Public Search. Retrieved from https://ppubs.uspto.gov/pubwebapp/static/pages/landing.html
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