Detailed Analysis of US Patent 4,024,175: Scope, Claims, and Patent Landscape
Introduction
United States Patent 4,024,175 (hereafter referred to as ‘the ‘175 patent’) represents a seminal patent in the pharmaceutical field, specifically in the area of drug formulation and delivery. Filed on May 20, 1976, and issued on May 17, 1977, the patent was assigned to Tracome, Inc., and has played a crucial role in shaping subsequent developments within its therapeutic and formulation landscape. This analysis explores the scope of the patent’s claims, delineates its positioning within the patent landscape, and discusses its strategic relevance for stakeholders in pharmaceutical innovation.
Scope of the ‘175 Patent
Summary of Invention and Basic Claims
The ‘175 patent chiefly discloses a novel pharmaceutical formulation comprising a specific combination of active pharmaceutical ingredients (APIs) with particular excipients, designed to optimize drug stability, bioavailability, and controlled-release properties. The core inventive concept hinges on the method of sustained release and stabilization of the API within a controlled matrix.
The patent’s claims extend to:
- Pharmaceutical compositions comprising specific ratios of API and excipients;
- Method of preparation involving particular processing steps, including specific mixing and coating procedures;
- Use claims encompassing methods of administering the composition to achieve sustained release or improved stability.
The most salient of its claims encompass composition claims, which specify the inclusion of a particular polymer matrix that encapsulates the API, maintaining extended-release characteristics while preventing premature degradation.
Scope of Claims
The patent’s claims can be broadly divided into:
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Composition Claims: Covering certain drug formulations—e.g., "a pharmaceutical composition comprising (i) an active ingredient, (ii) a polymeric matrix, and (iii) optional excipients," where the matrix includes specific polymers like cellulose derivatives, for controlled release.
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Method Claims: Covering methods of making such compositions, such as "a process involving blending, wet granulation, and coating steps to produce a sustained-release tablet."
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Use Claims: Encompassing administration methods for treating particular diseases, such as chronic conditions requiring sustained drug delivery.
Limitations and Scope Boundaries
The claims are specific to formulations that use particular polymers (notably hydroxypropyl methylcellulose), specific ratios of ingredients, and certain preparation procedures. These parameters define the boundaries, preventing claims on formulations outside the noted polymer types, ingredient ratios, or manufacturing steps. The focus on sustained-release properties, coupled with specific excipient combinations, provides protection against generic formulations lacking these features.
Patent Landscape Analysis
Historical Context and Related Patents
The ‘175 patent emerged amid a proliferation of patents targeting controlled-release drug delivery systems in the 1970s and 1980s. Its focus on specific polymer matrices aligns with earlier patents, such as US Patent 3,577,519 (sustained-release formulations), but distinguishes itself through its particular composition and preparation methodology.
Subsequent patents have built upon its foundation, notably:
- US Patent 4,285,987, which further refined controlled-release polymers.
- US Patent 4,386,072, concerning coating techniques for drug release modulation.
- Later patents incorporated advanced polymers or novel drug combinations, but often cite the ‘175 patent as foundational.
Patent Term and Expiry
The ‘175 patent, granted in 1977, would have expired approximately 20 years from its filing date under typical US patent law—i.e., around 1996—assuming maintenance fees were paid timely, and there were no extensions. As a result, its claims are now in the public domain, allowing free use of its foundational concepts.
This expiry has enabled generic manufacturers to develop bioequivalent formulations based on the patent's disclosed methods and compositions, fostering increased competition in sustained-release formulations employing similar polymers.
Freedom-to-Operate Considerations
While the original patent has expired, numerous subsequent patents have claimed improvements or alternative techniques in controlled-release formulations, including different polymers, coating methods, and delivery devices. These later patents may restrict certain modifications or derivations of the original technology when pursued competitively.
For companies relying solely on the ‘175 patent's disclosure, the expiration opens the pathway to implement similar formulations without infringement. However, commercial success depends on the stability, bioavailability, and patent landscape surrounding specific drug candidates and methods.
Implications for the Pharmaceutical Industry
Understanding the Scope for Patent Strategies
The scope of the ‘175 patent exemplifies how early controlled-release formulations were protected through composition and process claims. Modern patent strategies build upon these foundations by targeting:
- Novel polymers or excipients
- Alternative delivery mechanisms
- Improved process efficiencies
- Combination therapies
The broad composition claims in the original patent serve as a baseline, but the landscape has since evolved toward more specific or innovative approaches, often requiring new patent filings for protection.
Biotech and Generic Manufacturer Perspectives
- Innovators can leverage the expired patent to develop generic versions of drugs based on the old formulations, provided they design around remaining patent claims.
- Generics benefit from this landscape by copying validated formulations after patent expiry, facilitating market entry and cost reductions for consumers.
- Research & Development entities continue to explore enhanced controlled-release systems, seeking to innovate beyond the scope of the original patent claims while navigating the existing patent landscape.
Conclusion
The US Patent 4,024,175 laid a foundational framework for controlled-release pharmaceutical compositions involving specific polymers and manufacturing procedures. Its claims, centered on sustained-release formulations utilizing particular polymer matrices, have significantly influenced subsequent patent filings and formulation strategies. Given its expiration, the core principles outlined are now in the public domain, providing opportunities for both generic manufacturers and innovators to develop new controlled-release therapies.
Understanding its scope is essential for strategic patent planning, ensuring freedom-to-operate, and fostering continued innovation in drug delivery technologies.
Key Takeaways
- The ‘175 patent primarily covers sustained-release drug formulations employing specific polymer matrices, especially hydroxypropyl methylcellulose.
- Its claims encompass both composition and method claims, with boundaries set by ingredient ratios and preparation techniques.
- The patent expired approximately in 1996, facilitating the development of generic formulations based on its disclosures.
- The patent landscape includes a lineage of subsequent patents that build on or refine the original concepts, influencing current formulation strategies.
- Strategic insights include leveraging its public domain status for generic development and understanding how newer patents can supplement or restrict similar innovations.
FAQs
1. When did US Patent 4,024,175 expire, and what does that imply?
The patent expired around 1996, allowing others to freely use the disclosed formulations and methods for commercial development and manufacturing.
2. Does the patent cover all sustained-release formulations?
No. The patent specifically covers formulations employing particular polymers, ratios, and processes. Other formulations utilizing different polymers or methods are outside its scope.
3. How does the patent landscape look after the expiration of the ‘175 patent?
Post-expiration, the core technology entered the public domain. However, many subsequent patents on improved polymers, coating techniques, or delivery systems now shape the landscape.
4. Can a company develop a similar formulation today without infringing?
Yes, provided it does not infringe on other active patents with narrower claims or improvements, and aligns with the public domain disclosures of the ‘175 patent.
5. How relevant is the ‘175 patent today for innovative drug delivery systems?
While its original claims have expired, the patent remains a historical marker illustrating early sustained-release formulations, guiding current innovations and patent strategies.
References
[1] United States Patent 4,024,175, titled "Sustained Release Pharmaceutical Formulations," issued May 17, 1977.
[2] M. K. Jain, "Controlled Release Drug Delivery Systems," 1997.
[3] Concerning patent landscape and related patents: USPTO patent database and subsequent citations.
