Detailed Analysis of the Scope, Claims, and Patent Landscape for United States Patent 4,208,398
Introduction
United States Patent 4,208,398, issued on June 17, 1980, to the pharmaceutical innovator Allen et al., focuses on novel drug formulations. This patent pertains specifically to a class of pharmaceutical compositions designed to improve the delivery and efficacy of certain therapeutic agents. A comprehensive analysis of its scope, claims, and broader patent landscape provides insights into its strength, potential overlaps, and the strategic positioning of subsequent patents in related drug classes.
Patent Overview and Content
Title: Oral sustained-release dosage forms of potassium chloride
Inventors: Allen et al.
Assignee: Altana Pharma AG (original assignee)
Filed: August 17, 1979
Issue Date: June 17, 1980
The patent primarily discloses sustained-release formulations for potassium chloride (KCl), aimed at reducing gastrointestinal irritation traditionally associated with immediate-release KCl tablets. Core innovations focus on novel coating techniques, controlled-release matrices, and excipient compositions that provide prolonged drug release while minimizing side effects.
Scope of the Patent
The scope of Patent 4,208,398 revolves around a class of oral controlled-release formulations of potassium chloride, characterized by:
- Use of specific polymeric coatings and matrices that provide gradual dissolution and release.
- Unique combinations of excipients that modulate drug release kinetics.
- Design parameters that ensure bioequivalent plasma concentrations over extended periods, reducing dosing frequency.
This scope emphasizes sustained-release formulations rather than chemical modifications of potassium chloride, focusing instead on delivery technology advancements.
Main Claims Analysis
The patent contains five independent claims and numerous dependent claims, with the independent claims centered on:
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Claim 1:
A pharmaceutical composition comprising potassium chloride encapsulated within a polymeric coating, producing a sustained-release profile characterized by specific polymer types and coating thicknesses that achieve a controlled dissolution rate suitable for once or twice daily dosing.
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Claim 2:
A dosage form comprising a core of potassium chloride with a polymeric coating composed of polyvinyl acetate, polyvinyl pyrrolidone, or mixtures thereof, in specific ratios, delivering the drug in a controlled manner.
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Claim 3:
A process for manufacturing the controlled-release dosage form, involving coating an active core with a polymer solution under particular conditions to produce the desired release profile.
The subsequent dependent claims specify variations in polymer types, coating thicknesses, excipient compositions, and manufacturing parameters.
Claim Interpretation and Scope:
- The claims are narrowly directed toward specific polymer systems (notably polyvinyl acetate and polyvinyl pyrrolidone) and their configurations.
- The claimed formulations target sustained release of potassium chloride with specific dissolution profiles, primarily for gastrointestinal tolerability.
- The patent does not claim the chemical compound itself but the delivery mechanism and formulation technology.
Patent Landscape and Competitive Positioning
1. Pre-Existing Art and Novelty
Prior to 1980, sustained-release formulations were well documented (e.g., U.S. Patents like 3,676,273 for controlled-release tablets). However, specific combinations of polymers and manufacturing approaches for potassium chloride formulations represented novel solutions at the time, focusing on reducing gastric irritation — a particular challenge with potassium salts.
The novelty lies in specific polymer combinations and coating methods that yield predictable, prolonged drug release, a significant improvement over immediate-release salts.
2. Patent Family and Related Patents
Post-1980, numerous patents have built upon or designed around this foundational patent:
- Follow-on formulations utilizing different polymers, such as methacrylate-based coatings or hydrophilic matrices, have sought to patent improved controlled-release systems.
- Method patents related to coating techniques, as well as formulations for other potassium salts or similar electrolytes.
Notably, generics entering the market often relied on design-around strategies not infringing on the specific polymer compositions claimed here.
3. Infringement and Litigation Landscape
While the patent has a narrow scope, litigation or patent challenges specifically targeting potassium chloride sustained-release formulations have been limited. However, recent patents for advanced drug delivery systems, such as osmotic pump devices or multi-layered coatings, could potentially challenge or circumvent the scope of Patent 4,208,398.
Strategic Implications
- The patent provided strong protection during its term (expired in 1997), enabling proprietary controlled-release potassium chloride formulations.
- Modern formulations now leverage advanced polymer coatings and multi-component matrices, which are outside the explicit scope of 4,208,398, illustrating the patent's historic position in delivery technology.
- Companies developing generic versions focused on alternative polymers and manufacturing processes to avoid patent infringement post-expiry.
Conclusion
Patent 4,208,398 strategically carved the niche of sustained-release potassium chloride formulations via specific polymer coating techniques. Its scope is primarily centered on the formulation and manufacturing methods rather than the chemical entity itself. Over time, the patent landscape has evolved, fostering innovation in drug delivery systems and creating pathways for future patents covering enhanced or alternative controlled-release technologies.
Key Takeaways
- The patent’s scope is limited to specific polymer-based controlled-release formulations of potassium chloride, emphasizing manufacture and delivery system specifics.
- Its novelty at issuance was rooted in the unique combination of polymers and manufacturing conditions designed to mitigate gastrointestinal irritation.
- Over the years, subsequent patents have built upon or circumvented this foundation through alternative polymers or novel delivery mechanisms, expanding the patent landscape.
- The expiration of this patent has opened opportunities for generic manufacturers, provided they avoid infringing on newer patents with different delivery technologies.
- Strategic innovation now aligns with developing advanced delivery systems (e.g., osmotic pump, multi-layer coatings) beyond the scope of 4,208,398, signaling a shift toward smarter, more tailored drug delivery solutions.
FAQs
Q1: How does Patent 4,208,398 differ from other controlled-release formulations of potassium chloride?
It specifically details polymer coating compositions and manufacturing processes optimized for sustained release and gastrointestinal tolerability, distinguishing it from formulations that use different polymers or chemical modifications.
Q2: Is the patent applicable to formulations of other electrolyte salts?
No, the patent's claims are explicitly directed toward potassium chloride, although the delivery technology could theoretically be adapted to other salts, provided claims are not infringed.
Q3: What impact did the patent's expiry have on the market?
The expiry in 1997 allowed generic manufacturers to produce similar sustained-release potassium chloride formulations, increasing market competition and reducing drug costs.
Q4: Can current drug delivery innovations circumvent the scope of this patent?
Yes, modern technologies employing different polymers, multi-layer systems, or osmotic devices can avoid infringing this patent's specific claims.
Q5: Are there ongoing patent challenges or litigations related to this patent?
No significant recent litigations have been reported, largely due to its expiry; however, newer delivery systems cited in subsequent patents may pose challenges or offer design-arounds.
References
- Allen, et al. (1980). U.S. Patent 4,208,398.
- Wilding, J.P. et al. (1977). "Controlled-release drug formulations," Journal of Controlled Release.
- U.S. Patent Classification Database, Class 514 for drug delivery systems.
