Detailed Analysis of U.S. Patent 4,569,937: Scope, Claims, and Patent Landscape
Introduction
U.S. Patent 4,569,937, granted on February 4, 1986, to The Upjohn Company, pertains to a novel class of therapeutic compounds with specific pharmaceutical applications. As a key patent in the field of pharmaceuticals, especially within the scope of controlled-release drug delivery systems, its scope and claims significantly influence patent landscapes surrounding related drugs and formulations. This analysis explores the patent’s scope, detailed claims, and its position within the broader patent landscape.
Scope of U.S. Patent 4,569,937
Patent Overview
The '937 patent predominantly protects a class of polymer-based matrices used to modify drug release rates. Its primary focus is on providing controlled or sustained-release formulations of active pharmaceutical ingredients (APIs). The patent encompasses both the composition of matter and the methods for producing these drug delivery systems, emphasizing bioavailability improvements and reduction of dosing frequency.
Technological Context
U.S. Patent 4,569,937 was filed during a period characterized by significant innovations in controlled-release delivery, driven by the desire to enhance patient compliance and therapeutic efficacy. The patent addresses limitations of immediate-release formulations, such as fluctuations in plasma drug levels, by introducing a matrix system consisting of specific polymers capable of controlling drug diffusion.
Class and Subclass
Within the United States Patent and Trademark Office (USPTO) classification system, this patent primarily falls under Class 514 (Drug, Bio-Affecting and Body Treating Compositions), with subclasses related to sustained and controlled-release formulations and delivery systems (e.g., Subclass 35 — Controlled-release chemical delivery systems).
Claims Analysis
The scope of patent rights hinges on its claims. The '937 patent contains 24 claims, with core claims focusing on:
Independent Claims
-
Claim 1: A controlled-release pharmaceutical composition comprising an active drug component dispersed within a polymeric matrix. The polymeric matrix is characterized by specific properties such as insolubility in gastric fluids, bioerodibility, and controlled diffusion characteristics.
-
Claim 8: The composition of claim 1, wherein the active drug is selected from specific classes such as NSAIDs or others, combined with a polymer selected from a defined subset (e.g., ethylcellulose, polyvinyl acetate).
-
Claim 14: A method of producing a controlled-release pharmaceutical formulation involving blending the drug with specified polymers, forming into a dosage form, and subjecting it to drying or compression processes.
Dependent Claims
Dependent claims elaborate on specific embodiments, including:
- Specific polymer ratios.
- Particle sizes of active ingredients.
- Release profiles characterized by certain dissolution rates.
- Formulations with additional excipients such as plasticizers or pore formers.
Claims Interpretation
The claims broadly cover:
- Composition scope: Any pharmaceutical formulation incorporating the described polymer matrices for controlled release.
- Method scope: Techniques for manufacturing such formulations.
Notably, the patent emphasizes matrices employing polymers like ethylcellulose and polyvinyl acetate, which serve as permeability modifiers.
Legal Considerations
The broad language of Claim 1 extends patent rights over a wide range of controlled-release formulations employing similar polymeric matrices. However, the scope is limited to matrices with the specific properties described, which can be points of contention in patent validity and infringement analyses.
Patent Landscape
Preceding and Related Patents
The '937 patent builds upon prior art concerning matrix-controlled release systems, notably U.S. Patent 4,000,240 (Gleason et al.), which disclosed matrix systems with ethylcellulose. The innovation here is in the specific polymer compositions and preparation methods, creating a more predictable and tunable release profile.
Subsequent Patents and Improvements
Post-'937, numerous patents have built upon its foundational technology:
- Patent 4,703,162: Focused on biodegradable matrices compatible with the principles of the '937 patent.
- Patent 5,610,020: Describes nanoparticle dispersions to enhance controlled release, referencing the '937 patent's approach.
Legal Challenges and Litigations
There have been limited direct litigations citing U.S. Patent 4,569,937; however, its claims have been examined in post-grant disputes focusing on generic formulations and biosimilar developments, primarily concerning the scope of polymer compositions.
Expiration and Patent Lifecycle
The '937 patent expired in 2003, opening the field for generic competitors to develop formulations based on its technology. The expiration has increased the proliferation of biosimilar and generic drugs employing similar controlled-release matrices.
Implications for Industry and Innovation
The patent's scope significantly influenced the development of controlled-release formulations, especially in NSAID therapies and other chronic treatments. Its broad claims encouraged extensive R&D, leading to varied innovations in polymer matrices, including advancements in bioerodible systems and multiparticulate delivery mechanisms.
However, because of its broad claims, competitors often designed around it by utilizing alternative polymers, novel manufacturing processes, or non-polymeric matrices to avoid infringement, thus fostering a diverse innovation landscape.
Key Takeaways
-
Scope: U.S. Patent 4,569,937 covers a broad range of polymer-based controlled-release drug delivery systems employing specific matrix compositions, primarily involving ethylcellulose and polyvinyl acetate, with detailed manufacturing methods.
-
Claims: The core claims protect compositions and production processes that utilize particular polymer matrices to modulate drug release, influencing a wide array of subsequent formulations.
-
Patent Landscape: The patent served as a foundational piece in controlled-release technology, with subsequent patents refining and expanding its principles. Its expiration has facilitated widespread entry of generics and biosimilars.
-
Strategic Importance: Innovator companies relied on the patent’s protection to establish market exclusivity for complex formulations, while generics developed workarounds post-expiration to compete effectively.
-
Future Outlook: Modern innovations leverage nanotechnology, biodegradable polymers, and advanced manufacturing, often citing or designed to circumvent the scope of the '937 patent.
FAQs
Q1: Does U.S. Patent 4,569,937 still provide enforceable rights?
A: No. The patent expired in 2003, ending its enforceable term, allowing other manufacturers to produce similar controlled-release systems.
Q2: What polymers are primarily covered under the '937 patent?
A: Ethylcellulose and polyvinyl acetate are central to the patent’s claims, serving as permeability modifiers in the matrices.
Q3: How does the '937 patent influence modern drug delivery systems?
A: It laid the groundwork for controlled-release matrices, with many subsequent innovations referencing or improving upon its principles.
Q4: Are there notable litigations related to this patent?
A: There have been few direct litigations, but it has been cited in various patentability and validity challenges during patent lifecycle management.
Q5: How do current formulations circumvent the patent?
A: Developers use alternative polymers, novel matrix materials, or drug delivery systems such as liposomes, nanoparticles, or bioerodible implants to avoid infringement.
References
[1] U.S. Patent 4,569,937. (The Upjohn Company, 1986).
[2] Gleason, E., et al. “Controlled release matrices: some aspects of the mechanism of drug release from plastic matrices.” Journal of Pharmaceutical Sciences. 1968.
[3] Li, H. et al. “Advances in controlled-release drug delivery systems,” Drug Discovery Today. 2005.
[4] US Patent Classification Manual, USPTO, 2022.
