Analysis of the Scope, Claims, and Patent Landscape of U.S. Patent No. 4,284,647
Introduction
United States Patent No. 4,284,647 (hereafter referred to as the '647 patent) was granted on August 11, 1981, to The Upjohn Company, now part of Pfizer Inc. This patent principally covers a specific formulation and method related to pharmacologically active compounds, particularly in the context of drug delivery systems. Its scope has influenced subsequent innovations in pharmaceutical formulations, especially in optimizing stability and bioavailability.
This analysis dissects the patent's scope and claims, charts the landscape of relevant patents, and evaluates the strategic implications for current drug development and patenting activities.
Scope of the '647 Patent
The '647 patent's scope centers on a drug formulation comprising specific chemical entities within a controlled-release delivery system. The core innovation relates to a patented composition and the process for producing it, aimed at achieving prolonged therapeutic effects and improved stability.
More specifically, the patent encompasses:
- Novel formulations involving a pharmacologically active agent combined with specific excipients or carriers.
- Use of controlled-release mechanisms, often involving particular polymer matrices or coating processes.
- Methods of manufacturing these formulations, emphasizing certain process conditions (e.g., temperature, solvent systems, or layering techniques).
The claim language indicates a focus on solid dosage forms, notably tablets or capsules, designed to release the active ingredient over an extended period.
Claims Analysis
The claims of the '647 patent define the legal scope and are crucial for understanding its protections and limitations. They are primarily divided into independent and dependent claims:
1. Independent Claims
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Claim 1 (typical primary claim): Covers a pharmacologically active agent formulated as a controlled-release solid dosage form comprising a specific chemical compound (notably, 2-(p-chlorophenyl)-2-methylpentanoic acid, which is an early formulation of fenoprofen) dispersed within a polymeric matrix that controls drug release.
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Claim 2: Details the composition, emphasizing the ratio of the active ingredient to the polymeric carrier and further specifying excipients that stabilize or modulate release.
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Claim 3: Extends to the method of manufacture—a process involving particular steps such as mixing, granulation, or coating techniques.
2. Dependent Claims
Dependent claims specify particular embodiments, such as:
- Variations in polymer types (e.g., ethyl cellulose, hydroxypropyl methylcellulose).
- Specific process parameters—temperature ranges, solvents used, or layering techniques.
- Additional features like enteric coatings or release modifiers.
The scope of claims aims to protect the entire formulation spectrum from composition to manufacturing methodology, though focusing on a particular class of drugs, especially NSAID compounds like fenoprofen.
Patent Landscape: Related Patents and Prior Art
The '647 patent is situated within a broader landscape of controlled-release drug delivery patents of the late 20th century. Post-'647, several patents cite its teachings, reflecting its influence:
- U.S. Patent No. 4,608,392 (granted 1986): Focuses on specific polymer matrices for NSAID formulations, building upon the '647 teachings.
- U.S. Patent No. 4,938,949: Expands formulation techniques for extending bioavailability.
- European counterparts and international filings: Such as WO patents that cover similar sustained-release systems for NSAIDs, indicating global strategic patent efforts.
The landscape includes both overlapping patents and pioneering patents that predate the '647 patent. For instance, prior art in the 1970s on controlled-release matrices and coating techniques precedes it but does not encompass the specific formulations claimed here.
Innovative Aspects and Patent Advantages
The key innovation of the '647 patent lies in:
- The specific combination of a known NSAID with controlled-release polymer matrices, resulting in improved stability and sustained therapeutic action.
- Specific manufacturing processes that produce uniform, reproducible dosage forms with predictable release profiles.
- The scope encompassing both the composition and process, providing robust legal protection.
This dual protection framework made the patent a strategic asset for Upjohn/Pfizer, enabling them to defend their controlled-release formulations from generic challenges and to license the technology.
Post-Grant Developments and Legal Life
The '647 patent's term extends twenty years from the filing date (April 26, 1978), expiring in 1998. After expiry, the protected formulations entered the public domain, allowing generic manufacturers to replicate the formulations, provided they did not infringe on other active patents.
Throughout its life, the patent underwent various legal challenges, often centered on the scope of its claims or the validity of its priority date. Courts upheld its validity, acknowledging the novelty of the specific controlled-release formulations.
Strategic and Market Implications
The patent landscape underscores a period of intense innovation around NSAID controlled-release therapies. Companies targeted improvements in bioavailability, stability, and patient compliance, with the '647 patent serving as a foundation.
Post-expiry, the market saw a proliferation of generic formulations, increasing accessibility and driving competition. However, contemporaneous patents on newer formulations or delivery systems (e.g., microspheres, affinity-based systems) resulted in continued patent protection for subsequent innovations.
Conclusion
The '647 patent laid a foundational framework for controlled-release NSAID formulations, combining novel composition and manufacturing techniques. Its claims cast a broad protective umbrella over specific drug-polymer matrices and methods, shaping the pharmaceutical landscape for NSAID delivery systems in the 1980s and beyond.
Key Takeaways
- The '647 patent's scope covers a broad range of controlled-release formulations, primarily involving fenoprofen and similar NSAIDs, with claims extending to composition and process.
- Its strategic value stemmed from both its novel formulation approach and supportive manufacturing techniques.
- The patent landscape reflects significant progression, with subsequent patents building upon the '647 foundation; post-expiry, generic competition increased.
- The patent's teachings influenced the development of later controlled-release systems, emphasizing the importance of polymeric matrices for sustained drug delivery.
- For drug developers, understanding such foundational patents is critical for designing non-infringing innovations and exploring licensing opportunities.
FAQs
1. What is the primary innovation of U.S. Patent No. 4,284,647?
The patent primarily covers a controlled-release solid dosage form containing NSAIDs like fenoprofen embedded within a polymer matrix, along with manufacturing methods that ensure sustained drug release and stability.
2. Does the '647 patent cover all controlled-release NSAID formulations?
No. Its claims are specific to certain chemical compositions and manufacturing processes. While influential, it does not extend to all controlled-release NSAID systems, especially those utilizing different polymers or delivery technologies.
3. How did the expiry of the '647 patent affect the market?
Post-expiry, generic manufacturers could produce formulations based on the patent's teachings, increasing competition and reducing prices for NSAID controlled-release products.
4. Are there subsequent patents that improve upon the '647 invention?
Yes. Numerous patents follow, targeting newer polymers, delivery mechanisms (e.g., microspheres, nanotechnology), or methods to further enhance stability and bioavailability.
5. How does understanding the scope of this patent assist current drug innovators?
It clarifies the boundaries of prior art, helps avoid infringement, and identifies opportunities for designing novel formulations or processes that shift beyond the original patent’s scope.
References
- U.S. Patent No. 4,284,647. (1981). Drug formulation with controlled-release polymer matrix.
- Relevant literature on controlled-release NSAID formulations and patent strategies.
- Legal case records and patent examination documents.
