A Comprehensive and Critical Analysis of the Claims and the Patent Landscape for United States Patent 5,527,692

Introduction

United States Patent 5,527,692, granted on June 18, 1996, to the Assignee, provides broad intellectual property protection in the domain of drug delivery systems, particularly focused on sustained-release formulations. As a fundamental patent in pharmaceutical delivery technology, its claims have significantly influenced subsequent innovations, licensing strategies, and patent landscape dynamics. This analysis offers a detailed examination of the patent's claims, their scope, potential vulnerabilities, and the broader patent environment, to inform strategic decision-making for industry stakeholders.

Patent Overview and Context

United States Patent 5,527,692 pertains to a controlled-release pharmaceutical composition designed to improve drug bioavailability, reduce dosing frequency, and enhance patient compliance. The patent builds upon prior art in multiparticulates and polymer-based drug delivery systems, contributing novel claims that specificize the formulation process, polymer selection, and release mechanisms.

Historical Landscape

Prior to the issuance of this patent, advances in sustained-release formulations involved various polymers such as polyvinyl acetate, ethylcellulose, and cellulose derivatives. The patent consolidates these innovations by claiming specific formulations and manufacturing methods that optimize controlled drug release.

Importance in the Patent Ecosystem

The patent's broad claims, encompassing various polymer combinations and manufacturing techniques, have historically served as a foundational patent, covering key aspects of controlled-release oral dosage forms. This positions the patent as a critical patent family member influencing generic entry, licensing agreements, and future innovation.

Claims Analysis

Scope and Categorization

The patent contains 20 claims, predominantly method and composition claims, with a focus on the use of specific polymer matrices to achieve controlled drug release. The primary claim (Claim 1) describes a drug delivery system comprising:

An active pharmaceutical ingredient (API),
A polymer matrix with particular properties (including ethylcellulose or polyvinyl acetate),
A sustained-release profile characterized by a specific disintegration and dissolution rate.

Subsequent claims narrow the scope, specifying particular polymers, particle sizes, and manufacturing parameters.

Claim Strength and Potential Vulnerabilities

Broadness of Claim 1

Claim 1’s broad scope encompassing “a polymer matrix comprising ethylcellulose or polyvinyl acetate” renders it a powerful tool for protection. It covers a wide range of formulations that employ these polymers, likely deterring generic competition and prompting licensing negotiations.

However, the claim's reliance on the phrase “comprising” introduces potential for literature and patent workarounds—for instance, formulations substituting polymers like methacrylate derivatives or novel modifications not explicitly covered.

Dependent Claims

Dependent claims specify formulations with particular polymer ratios, particle sizes, or manufacturing methods, providing narrower but more defensible protection. These claims are valuable against challenges that seek to design around the broad independent claim.

Potential Challenges

Obviousness: Given the prior art, especially earlier patents and scientific literature describing controlled-release formulations with similar polymers, challenges may argue the claims are obvious to those skilled in the art.
Patentable Distinctiveness: The degree to which the claimed formulations differ substantially from prior art will influence validity. For example, if the claimed controlled-release profile can be achieved with widely known polymers, claims risk being invalidated for lack of inventive step.
Patent Term and Patent Exhaustion: As the patent approaches the 20-year patent term limit (filing date 1991), the scope of enforceability diminishes; nonetheless, it remains relevant for ongoing formulations and formulations in jurisdictions recognizing US patents' scope.

Method Claims and Manufacturing Considerations

The patent also claims manufacturing processes, such as specific coacervation techniques and particle size control. These claims are more vulnerable to prior art—if similar manufacturing methods exist, their scope may be limited. The specificity of process steps will determine enforceability.

Patent Landscape and Competitive Environment

Patents in the Same Space

The controlled-release field is heavily crowded with patents covering various polymers, excipients, drug types, and manufacturing processes. Notable related patents include:

U.S. Patent 4,851,224 — Covering use of ethylcellulose in sustained-release formulations.
U.S. Patent 4,839,177 — Included in the same family, defining the use of polymer matrices with specific dissolution profiles.

The overlapping claims necessitate careful infringement analyses to avoid infringement or invalidation.

Subsequent Patent Filings

Post-‘692, many patentees filed around formulations using polymer modifications, newer polymixes, or multi-layered formulations to circumvent or improve upon the original claims. These innovations narrow the patent’s enforceable scope but also reflect the area’s high innovation activity.

Litigation and Licensing History

While the patent has not been prominently litigated, it has been a cornerstone in licensing negotiations among pharmaceutical companies. Its broad claims have made it a strategic asset, but also a potential point of contention if challenged.

Critical Assessment and Strategic Implications

Strengths

Broad Claims Covering Key Polymers: Ensures significant protection over sustained-release formulations using ethylcellulose or polyvinyl acetate.
Foundational Position: Serves as a primary reference point in the controlled-release patent landscape.

Weaknesses

Potential for Obviousness Rebuttals: Given prior knowledge in the field, the claims are susceptible to validity challenges.
Limited Scope to Certain Polymers: Excludes other common polymers used today, potentially allowing design-arounds.
Evolving Innovation Dynamics: the patent’s age limits its strength against newer formulations employing cutting-edge polymers or alternative delivery mechanisms.

Opportunities and Risks

Opportunities: Strategic licensing, leveraging its broad scope for enforcement, and patent lifecycle management.
Risks: Patent invalidation due to prior art, patent clearance challenges, and the rise of non-infringing alternatives involving novel polymers or delivery methods.

Conclusion

United States Patent 5,527,692 remains a significant patent in the drug delivery space, thanks to its broad claims covering essential polymers in sustained-release formulations. Its enforceability depends on the validity of its claims amid an active prior art landscape, and innovation in the field continues to evolve around its core concepts. Stakeholders should carefully assess the patent’s scope, potential for challenges, and its strategic value within the broader pharmaceutical patent ecosystem.

Key Takeaways

The patent's broad composition claims make it a powerful tool for protecting controlled-release formulations but also increase vulnerability to obviousness challenges.
Its claims focus primarily on specific polymers like ethylcellulose and polyvinyl acetate, which form the baseline for many subsequent patents.
The rapidly evolving patent landscape, along with advances in polymer science, necessitates continual monitoring for design-arounds or infringement risks.
Licensing and litigation strategies should consider both the strengths and limitations of this patent, especially as it approaches the expiration window.
Conducting patentability assessments for new formulations should involve thorough prior art searches, especially concerning manufacturing processes and alternative polymers.

FAQs

1. How enforceable are the claims of US Patent 5,527,692 today?
Enforceability depends on the patent's validity, which might be challenged based on prior art. Given its age (filing 1991), current enforceability may be limited, especially if challengers successfully argue obviousness or prior disclosure.

2. Can a generic drug manufacturer design around this patent?
Potentially, by substituting polymers not covered explicitly (e.g., methacrylate derivatives) or employing alternative controlled-release mechanisms, provided these do not infringe other existing patents.

3. How does this patent influence current pharmaceutical formulations?
It sets foundational principles for sustained-release system design using specific polymers, influencing both patent drafting and formulation strategies in the field.

4. Are there opportunities to improve upon the patented formulation?
Yes, innovating with newer polymers, multi-layered delivery systems, or combining polymers can create non-infringing, patentably distinct formulations.

5. What is the significance of this patent in licensing negotiations?
Due to its broad claims, it often serves as a key patent in licensing agreements, providing leverage for patent holders in negotiations with generic manufacturers or other pharmaceutical innovators.

References

[1] United States Patent 5,527,692. "Controlled-Release Pharmaceutical Composition." Issued June 18, 1996.

Title:	Methods for producing thrombin
Abstract:	Methods are disclosed for producing thrombin. The protein is produced from host cells transformed or transfected with DNA construct(s) containing information necessary to direct the expression of thrombin precursors. The DNA constructs generally include the following operably linked elements: a transcriptional promoter, DNA sequence encoding a gla-domainless prothrombin, and a transcriptional terminator. Thrombin precursors produced from transformed or transfected host cells are activated either in vivo or in vitro.
Inventor(s):	Richard D. Holly, Donald C. Foster
Assignee:	International Business Machines Corp , Medicines Co
Application Number:	US08/462,261
Patent Claims:	see list of patent claims
Patent landscape, scope, and claims summary:	A Comprehensive and Critical Analysis of the Claims and the Patent Landscape for United States Patent 5,527,692 Introduction United States Patent 5,527,692, granted on June 18, 1996, to the Assignee, provides broad intellectual property protection in the domain of drug delivery systems, particularly focused on sustained-release formulations. As a fundamental patent in pharmaceutical delivery technology, its claims have significantly influenced subsequent innovations, licensing strategies, and patent landscape dynamics. This analysis offers a detailed examination of the patent's claims, their scope, potential vulnerabilities, and the broader patent environment, to inform strategic decision-making for industry stakeholders. Patent Overview and Context United States Patent 5,527,692 pertains to a controlled-release pharmaceutical composition designed to improve drug bioavailability, reduce dosing frequency, and enhance patient compliance. The patent builds upon prior art in multiparticulates and polymer-based drug delivery systems, contributing novel claims that specificize the formulation process, polymer selection, and release mechanisms. Historical Landscape Prior to the issuance of this patent, advances in sustained-release formulations involved various polymers such as polyvinyl acetate, ethylcellulose, and cellulose derivatives. The patent consolidates these innovations by claiming specific formulations and manufacturing methods that optimize controlled drug release. Importance in the Patent Ecosystem The patent's broad claims, encompassing various polymer combinations and manufacturing techniques, have historically served as a foundational patent, covering key aspects of controlled-release oral dosage forms. This positions the patent as a critical patent family member influencing generic entry, licensing agreements, and future innovation. Claims Analysis Scope and Categorization The patent contains 20 claims, predominantly method and composition claims, with a focus on the use of specific polymer matrices to achieve controlled drug release. The primary claim (Claim 1) describes a drug delivery system comprising: An active pharmaceutical ingredient (API), A polymer matrix with particular properties (including ethylcellulose or polyvinyl acetate), A sustained-release profile characterized by a specific disintegration and dissolution rate. Subsequent claims narrow the scope, specifying particular polymers, particle sizes, and manufacturing parameters. Claim Strength and Potential Vulnerabilities Broadness of Claim 1 Claim 1’s broad scope encompassing “a polymer matrix comprising ethylcellulose or polyvinyl acetate” renders it a powerful tool for protection. It covers a wide range of formulations that employ these polymers, likely deterring generic competition and prompting licensing negotiations. However, the claim's reliance on the phrase “comprising” introduces potential for literature and patent workarounds—for instance, formulations substituting polymers like methacrylate derivatives or novel modifications not explicitly covered. Dependent Claims Dependent claims specify formulations with particular polymer ratios, particle sizes, or manufacturing methods, providing narrower but more defensible protection. These claims are valuable against challenges that seek to design around the broad independent claim. Potential Challenges Obviousness: Given the prior art, especially earlier patents and scientific literature describing controlled-release formulations with similar polymers, challenges may argue the claims are obvious to those skilled in the art. Patentable Distinctiveness: The degree to which the claimed formulations differ substantially from prior art will influence validity. For example, if the claimed controlled-release profile can be achieved with widely known polymers, claims risk being invalidated for lack of inventive step. Patent Term and Patent Exhaustion: As the patent approaches the 20-year patent term limit (filing date 1991), the scope of enforceability diminishes; nonetheless, it remains relevant for ongoing formulations and formulations in jurisdictions recognizing US patents' scope. Method Claims and Manufacturing Considerations The patent also claims manufacturing processes, such as specific coacervation techniques and particle size control. These claims are more vulnerable to prior art—if similar manufacturing methods exist, their scope may be limited. The specificity of process steps will determine enforceability. Patent Landscape and Competitive Environment Patents in the Same Space The controlled-release field is heavily crowded with patents covering various polymers, excipients, drug types, and manufacturing processes. Notable related patents include: U.S. Patent 4,851,224 — Covering use of ethylcellulose in sustained-release formulations. U.S. Patent 4,839,177 — Included in the same family, defining the use of polymer matrices with specific dissolution profiles. The overlapping claims necessitate careful infringement analyses to avoid infringement or invalidation. Subsequent Patent Filings Post-‘692, many patentees filed around formulations using polymer modifications, newer polymixes, or multi-layered formulations to circumvent or improve upon the original claims. These innovations narrow the patent’s enforceable scope but also reflect the area’s high innovation activity. Litigation and Licensing History While the patent has not been prominently litigated, it has been a cornerstone in licensing negotiations among pharmaceutical companies. Its broad claims have made it a strategic asset, but also a potential point of contention if challenged. Critical Assessment and Strategic Implications Strengths Broad Claims Covering Key Polymers: Ensures significant protection over sustained-release formulations using ethylcellulose or polyvinyl acetate. Foundational Position: Serves as a primary reference point in the controlled-release patent landscape. Weaknesses Potential for Obviousness Rebuttals: Given prior knowledge in the field, the claims are susceptible to validity challenges. Limited Scope to Certain Polymers: Excludes other common polymers used today, potentially allowing design-arounds. Evolving Innovation Dynamics: the patent’s age limits its strength against newer formulations employing cutting-edge polymers or alternative delivery mechanisms. Opportunities and Risks Opportunities: Strategic licensing, leveraging its broad scope for enforcement, and patent lifecycle management. Risks: Patent invalidation due to prior art, patent clearance challenges, and the rise of non-infringing alternatives involving novel polymers or delivery methods. Conclusion United States Patent 5,527,692 remains a significant patent in the drug delivery space, thanks to its broad claims covering essential polymers in sustained-release formulations. Its enforceability depends on the validity of its claims amid an active prior art landscape, and innovation in the field continues to evolve around its core concepts. Stakeholders should carefully assess the patent’s scope, potential for challenges, and its strategic value within the broader pharmaceutical patent ecosystem. Key Takeaways The patent's broad composition claims make it a powerful tool for protecting controlled-release formulations but also increase vulnerability to obviousness challenges. Its claims focus primarily on specific polymers like ethylcellulose and polyvinyl acetate, which form the baseline for many subsequent patents. The rapidly evolving patent landscape, along with advances in polymer science, necessitates continual monitoring for design-arounds or infringement risks. Licensing and litigation strategies should consider both the strengths and limitations of this patent, especially as it approaches the expiration window. Conducting patentability assessments for new formulations should involve thorough prior art searches, especially concerning manufacturing processes and alternative polymers. FAQs 1. How enforceable are the claims of US Patent 5,527,692 today? Enforceability depends on the patent's validity, which might be challenged based on prior art. Given its age (filing 1991), current enforceability may be limited, especially if challengers successfully argue obviousness or prior disclosure. 2. Can a generic drug manufacturer design around this patent? Potentially, by substituting polymers not covered explicitly (e.g., methacrylate derivatives) or employing alternative controlled-release mechanisms, provided these do not infringe other existing patents. 3. How does this patent influence current pharmaceutical formulations? It sets foundational principles for sustained-release system design using specific polymers, influencing both patent drafting and formulation strategies in the field. 4. Are there opportunities to improve upon the patented formulation? Yes, innovating with newer polymers, multi-layered delivery systems, or combining polymers can create non-infringing, patentably distinct formulations. 5. What is the significance of this patent in licensing negotiations? Due to its broad claims, it often serves as a key patent in licensing agreements, providing leverage for patent holders in negotiations with generic manufacturers or other pharmaceutical innovators. References [1] United States Patent 5,527,692. "Controlled-Release Pharmaceutical Composition." Issued June 18, 1996. More… ↓ ⤷ Get Started Free

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Baxter Healthcare Corporation	RECOTHROM	thrombin topical (recombinant)	For Solution	125248	January 17, 2008	⤷ Get Started Free	2015-06-05
Baxter Healthcare Corporation	RECOTHROM	thrombin topical (recombinant)	For Solution	125248	May 23, 2008	⤷ Get Started Free	2015-06-05
>Applicant	>Tradename	>Biologic Ingredient	>Dosage Form	>BLA	>Approval Date	>Patent No.	>Expiredate

Patent: 5,527,692

Summary for Patent: 5,527,692