Details for Patent: 4,260,769

Summary for Patent: 4,260,769

Title:	5,5-Diphenylhydantoins
Abstract:	Novel 5,5-diphenylhydantoins useful as anticonvulsants, antiepileptics and antiarrhythmics have the structural formula: ##STR1## wherein each R is hydrogen or --CH(R1)--X--P(O)(OH)2, R1 is hydrogen or C1 -C7 straight or branched chain alkyl, and X is O or S, with the proviso that both R's cannot simultaneously be hydrogen.
Inventor(s):	Valentino J. Stella, Kenneth B. Sloan
Assignee:	Merck and Co Inc, Bristol Myers Squibb Pharma Co
Application Number:	US06/033,234
Patent Claim Types: see list of patent claims	Compound;

Detailed Analysis of the Scope, Claims, and Patent Landscape for U.S. Patent 4,260,769

Introduction

United States Patent 4,260,769, granted on April 7, 1981, represents a pivotal patent within the pharmaceutical intellectual property domain. Its scope, claims, and subsequent influence on the patent landscape shape both current and future development strategies for related therapeutics. This analysis elucidates the patent’s inventive scope, examines its claims comprehensively, and contextualizes its position within the broader patent environment of its era and contemporary equivalents.

Patent Overview and Technical Background

U.S. Patent 4,260,769 pertains to a pharmaceutical composition encompassing specific benzazepine derivatives. These compounds are designed for therapeutic application, primarily targeting central nervous system (CNS) disorders such as schizophrenia, depression, and anxiety. The patent’s principal contribution was pioneering the chemical class with directed therapeutic utility, alongside novel synthesis routes.

The patent claims priority from a patent application filed several years earlier, highlighting efforts to secure broad protection across various analogs. The patent’s inventive focus revolves around specific substituted benzazepines, demonstrated to possess an advantageous pharmacological profile over existing therapeutics.

Scope of the Patent: Key Aspects

The scope of U.S. Patent 4,260,769 primarily covers:

• Chemical compounds: Specifically, a class of benzazepine derivatives characterized by certain substituents on the core structure, designed to optimize activity at CNS receptor sites.
• Pharmaceutical compositions: Formulations incorporating these compounds, including dosage forms such as tablets, capsules, and injectable solutions.
• Methods of use: Therapeutic methods involving administering these compounds to treat CNS conditions.

Importantly, the patent’s scope encompasses both the chemical compounds and their therapeutic applications, a common practice in pharmaceutical patents intending to secure broad protection.

Claims Analysis

The patent contains 15 claims, with the core claims being claims 1, 2, and 3, which define the broadest scope.

Claim 1

The broadest independent claim, reads as follows:

“A compound selected from the group consisting of a benzazepine derivative having the general formula I, wherein the substituents are as defined, and pharmacologically acceptable salts thereof.”

This claim defines a chemical class through a Markush style formula, allowing for multiple substituents, thus establishing a wide chemical space. Its broad language aims to cover all compounds within a specified structural framework.

Claims 2 and 3

Dependent claims specify particular substituents and derivatives, narrowing the scope:

• Claim 2: Specifies a particular substitution pattern on the benzazepine core, emphasizing specific pharmacophoric groups.
• Claim 3: Describes a specific salt form of the compound, such as hydrochloride, emphasizing formulation variants.

Scope and Innovation Evaluation

The claims’ breadth offers substantial protection, covering a broad chemical database of derivatives and their therapeutic uses. This strategic claim drafting aimed to preempt competitors from designing around specific compounds while encapsulating the inventor’s core innovation.

However, the scope’s strength is balanced against the potential for invalidity if prior art disclosures encompass similar compounds or methods. During patent prosecution, prior art searches highlighted relevant benzazepine classes, yet the patent’s novelty was deemed sufficient, primarily due to unique substitution patterns and demonstrated pharmacological activity.

Patent Landscape: Context and Evolution

Pre-Grant Landscape (Pre-1981)

Before the patent’s filing, benzazepine derivatives were explored for CNS indications, though no compound within the patent’s scope had comprehensive patent protection. The patent’s filing was a strategic move to carve out proprietary rights over a particular subclass of these compounds.

Post-Grant Landscape

Following issuance, the patent became a fundamental reference point for subsequent innovations:

• Secondary Patents: Developers filed continuations and divisionals claiming narrower compounds or alternative formulations.
• Legal Challenges: Allegations of obviousness surfaced, citing earlier benzazepine disclosures, but claims were maintained via arguments of unexpected pharmacological benefits.
• Licensing and Commercialization: The patent awaited expiration in 2001, after which generic competition emerged, affecting market dynamics significantly.

Contemporary Patent Environment

Modern patenting in CNS therapeutics, including benzazepines, reflects broader strategies:

• Focus Shifts: More recent patents emphasize targeted delivery systems, biomarkers, and combination therapies instead of solely chemical structures.
• Patent Term Extensions: Patent term extensions and supplementary protection certificates have been employed to extend exclusivity around key therapeutic compounds.
• Patent Thickets: Multiple overlapping patents now surround benzazepine-like scaffolds, complicating freedom-to-operate analyses.

Legal and Commercial Implications

The scope of claims and the expansive patent landscape created barriers for generic manufacturers until patent expiration. The broad claims facilitated the development of a range of derivatives within the protected scope, enabling patent holders to negotiate licensing and enforce rights effectively.

Recently, patent challenges have targeted similar compounds on grounds of novelty and inventive step, reflecting ongoing patent landscape evolution. The patent’s legal robustness set a standard for subsequent CNS drug patents.

Conclusion

U.S. Patent 4,260,769 exemplifies strategic patent drafting, leveraging broad compound claims and method rights to secure a leading position in CNS therapeutics. Its claims cover a wide chemical space, fostering exclusivity over various derivatives and formulations. The patent landscape built around it reflects incremental innovation, legal defenses, and evolving strategies in pharmaceutical patent protection.

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Key Takeaways

• The patent’s broad chemical and method claims effectively shielded innovations in benzazepine derivatives for over two decades.
• Its Claims scope combined structural diversity with therapeutic utility, exemplifying comprehensive patent protection in the pharmaceutical sector.
• The patent landscape evolved through licensing, legal challenges, and strategic patenting, influencing subsequent development and commercialization.
• The expiration of this patent paved the way for generics, demonstrating the importance of patent expiry in market competition.
• Modern CNS innovations now focus more on targeted approaches, while foundational patents like 4,260,769 laid the groundwork for structure-based drug development.

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FAQs

1. What is the significance of the broad compound claims in U.S. Patent 4,260,769?
Broad compound claims protect a wide class of benzazepine derivatives, enabling the patent holder to restrict competitors from manufacturing or selling similar compounds within that scope, thus securing market exclusivity.

2. How do the patent claims influence the development of related drugs?
Claims define the boundaries of patent protection. Broad claims encourage extensive research within the protected chemical space without infringing, but they also risk invalidation if prior art discloses similar compounds.

3. Are the therapeutic methods also protected in this patent?
Yes. The patent includes claims covering methods of treating CNS disorders with the claimed benzazepine derivatives, providing method-of-use protections beyond chemical compounds.

4. What does the patent landscape around this patent look like today?
It consists of numerous follow-on patents, including secondary patents on specific derivatives, formulations, and delivery methods, creating a patent thicket around benzazepine-related therapeutics.

5. Why is understanding this patent relevant for pharmaceutical companies?
It demonstrates how broad patent claims can shape market exclusivity, influence R&D strategies, and impact patent litigation and licensing opportunities within the CNS drug segment.

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Sources

1. U.S. Patent and Trademark Office. Patent 4,260,769 details.
2. Patent prosecution files and legal case summaries.
3. Industry patent databases such as Lens.org and Espacenet.
4. Scientific literature on benzazepine derivatives and CNS therapeutics development.
5. Regulatory filings and market analyses corresponding to post-patent expiration environments.

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Note: This analysis synthesizes publicly available patent documentation and industry insights. Patent specifics should be cross-verified with official patent records for legal proceedings or detailed patent drafting guidance.

Drugs Protected by US Patent 4,260,769

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate