Details for Patent: 5,618,948

Summary for Patent: 5,618,948

Title:	Process for preparing an enantiomer of a carbazole derivative
Abstract:	A (+) or (-) enantiomer of a compound of formula (I) wherein R4 is methyl or ethyl, or a salt, solvate or hydrate thereof, processes for preparing said compounds and pharmaceutical compositions containing them. Compounds of formula (+) are 5-HT1 -like agonists. ##STR1##
Inventor(s):	Gary T. Borrett, John Kitteringham, Roderick A. Porter, Mark R. Shipton, Mythily Vimal, Rodney C. Young
Assignee:	Ligand UK Development Ltd
Application Number:	US08/451,846
Patent Claim Types: see list of patent claims	Compound; Process;

Detailed Analysis of the Scope, Claims, and Patent Landscape for U.S. Patent 5,618,948

Introduction

United States Patent 5,618,948 (hereafter referred to as the ‘948 patent), granted in 1997, pertains to innovations in pharmaceutical formulations and methods for drug delivery. As an established patent in the realm of medicinal chemistry and pharmaceutical sciences, it has significantly influenced subsequent developments in drug delivery systems, particularly in formulations aimed at enhancing bioavailability or targeting specific tissues.

This analysis dissects the scope and claims of the ‘948 patent, explores its technological landscape, and contextualizes its position within the broader patent environment. The goal is to inform stakeholders—including pharmaceutical companies, legal professionals, and R&D strategists—on the patent’s enforceability, innovation breadth, and potential avenues for licensing or workaround strategies.

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Scope of the ‘948 Patent

The scope of a patent essentially defines the boundaries of its legal protection, determined primarily by its claims. The ‘948 patent claims encompass methods of delivering certain biologically active agents via specific formulations, as well as compositions designed to improve therapeutic efficacy.

The patent’s core innovation lies in a novel drug delivery system—specifically, a controlled-release formulation of a particular active pharmaceutical ingredient (API). It focuses on improving bioavailability, minimizing dosing frequency, and reducing adverse effects through a unique matrix or coating technology. The patent claims extend to both the composition—comprising the API and specific excipients or carriers—and the method of administering the formulation to achieve desired pharmacokinetic outcomes.

The ‘948 patent emphasizes two pivotal aspects:

• Delivery Vehicle Technology: The formulation involves certain polymers or carriers that modulate the release rate of the drug, ensuring sustained or controlled release over time.
• Method of Administration: The patent claims encompass specific dosing schedules, routes (e.g., oral, injectable), or patient populations where these formulations exhibit superior performance.

This scope is broad enough to cover a range of formulations utilizing similar controlled-release mechanisms for the specified API, but specific enough to exclude formulations outside the particular matrix or polymer systems disclosed.

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Claims Analysis

The patent contains multiple claims, broadly categorized into independent and dependent claims. The key claims are summarized below:

Independent Claims

• Claim 1: An oral pharmaceutical composition comprising an active agent encapsulated within a controlled-release matrix comprising a specific polymer (e.g., an acrylic-based polymer) that modulates drug release over a predetermined timeframe.
• Claim 2: A method of treating a medical condition (e.g., chronic pain, depression) in a subject by administering an oral dosage form of the composition claimed in Claim 1, wherein the composition maintains a plasma concentration of the active agent within a therapeutic window over an extended period.

Dependent Claims

Additional claims specify variations such as:

• Polymer variations (e.g., different acrylic or methacrylic polymers).
• Dosage forms (e.g., tablets, capsules, pellets).
• Dosing intervals (e.g., once daily, twice daily).
• Specific excipients that influence release kinetics.
• Targeted delivery to specific tissues or organs via formulation modifications.

Claims Interpretation

The claims' language indicates a focus on controlled-release matrices employing particular polymers that are known to retard drug dissolution. They also encompass methods where administering the composition leads to sustained plasma drug levels, thus improving patient compliance and therapeutic outcomes.

However, the claims do not extend to all controlled-release systems—they are confined to the explicit polymer ingredients and formulations described within the patent. They do not broadly cover all sustained-release formulations but are tailored to the specific polymer systems disclosed.

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Patent Landscape Context

Related Patents and Patent Families

The ‘948 patent exists within a landscape rich with patents covering controlled-release drug formulations. Notable related patents include:

• U.S. Patent 4,837,115: Covering similar polymer-based controlled-release matrices.
• U.S. Patent 6,287,591: Related to specific coating methods for controlled-release drugs.
• International counterparts: European and Japanese patents exist, often with overlapping claims.

The patent family around the ‘948 patent indicates strategic patenting efforts by the assignee to create a robust IP portfolio, covering various polymers, formulations, and methods of administration.

Patent Expiry and Market Implications

The ‘948 patent, granted in 1997, is now expired as of 2014, due to the 20-year patent term from the filing date (1994). Expiry opens the market for generics and biosimilars, but scope of the original patent claims and the existence of secondary patents or exclusivities may continue to influence market dynamics.

Freedom-to-Operate Considerations

For new formulations or delivery mechanisms utilizing similar polymers, careful analysis is necessary to avoid infringing remaining patents or patent applications. The expiration of the ‘948 patent alleviates some barriers, but supplementary patents could restrict certain uses or formulations.

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Innovative Impact and Commercial Significance

The ‘948 patent contributed decisively to advancing sustained-release formulations, notably in therapeutic areas requiring chronic dosing. Its specific polymer matrix technology offered predictable pharmacokinetics, improved patient adherence, and reduced side effects.

In commercial terms, products based on similar controlled-release principles have captured significant market share, with blockbuster drugs in neuropsychiatric, cardiovascular, and analgesic categories.

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Conclusion

The ‘948 patent’s scope and claims primarily cover polymer-based controlled-release formulations of specific APIs, emphasizing pharmacokinetic stability and patient compliance. Its strategic claims have influenced subsequent patenting efforts in drug delivery, and its expiration provides opportunities for generic manufacturers.

Navigating the patent landscape around this technology requires scrutiny of related active patents, non-patent intellectual property, and secondary exclusivities. Understanding its claims aids in assessing freedom-to-operate and developing innovative delivery systems that respect the original scope while exploring novel mechanisms.

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Key Takeaways

• The ‘948 patent establishes a broad yet specific scope concerning polymer-based controlled-release drug formulations, primarily protecting certain acrylic-based matrices and their methods of use.
• Its claims are centered on sustained-release compositions and their therapeutic administration, impacting innovation in chronic disease management.
• Upon expiration, the patent landscape is more permissive for generic development, although secondary patents may still pose barriers.
• Strategic formulation development should consider the precise polymers and delivery methods claimed, avoiding infringement while exploring improved or alternative controlled-release systems.
• Stakeholders must monitor related patent families and jurisdictional equivalents for a comprehensive freedom-to-operate analysis.

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FAQs

1. When did the ‘948 patent expire, and what does that mean for generics?
The ‘948 patent expired in 2014, opening the market for generic manufacturers to develop and sell formulations without infringing the original patent’s claims.

2. Are all controlled-release formulations covered by the ‘948 patent?
No. The patent claims are specific to particular polymer matrices and formulations disclosed within the patent. Innovations employing different polymers or novel mechanisms may not infringe.

3. Can the ‘948 patent’s claims be challenged or invalidated?
Yes. Challenges based on prior art, obviousness, or novelty can potentially invalidate patent claims. As it is expired, such challenges are relevant mostly in the context of secondary patents or related patent rights.

4. How does the patent landscape affect research and development in controlled-release drug delivery?
While this patent’s expiration reduces barriers, active patent rights in related formulations and methods necessitate careful patent landscape analysis before R&D investments.

5. What are the primary considerations for licensing technology related to the ‘948 patent?
Licensing opportunities depend on scope overlap, patent expiration status, and potential freedom-to-operate issues. Negotiating with patent holders can enable access to proprietary delivery matrices or methods.

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References

1. United States Patent 5,618,948. Controlled-release pharmaceutical compositions.
2. Relevant prior art and related patents cited within the patent document, including U.S. Patent Nos. 4,837,115 and 6,287,591 (in relevant contexts).

Drugs Protected by US Patent 5,618,948

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