When do biologic drug patents expire and when will biosimilars launch?

A Comprehensive and Critical Analysis of the Claims and Patent Landscape for United States Patent 5,494,799

Introduction

United States Patent 5,494,799 (hereafter “the ’799 patent”) represents a significant milestone within its technological domain, offering a detailed landscape for innovators, legal professionals, and market analysts. This patent, granted on February 27, 1996, addresses innovations in the field of drug delivery systems, specifically pertaining to controlled-release pharmaceutical formulations. An accurate assessment of its claims and the surrounding patent landscape is vital for understanding its influence, potential freedom-to-operate, and the scope of existing intellectual property rights.

This article provides a rigorous and critical analysis of the ’799 patent’s claims, evaluates their scope and validity, and explores the broader patent landscape, including related patents and citation patterns. Emphasizing precise, objective insights, it aims to inform strategic decision-making within the pharmaceutical and biotechnology sectors.

Overview of the ’799 Patent

Title: Controlled release formulations of diltiazem hydrochloride.

Inventors: Robert L. Swartz, et al.

Assignee: Benjamin H. Johnson.

Filing Date: December 15, 1993

Grant Date: February 27, 1996

The patent primarily claims a controlled-release formulation of diltiazem hydrochloride—a calcium channel blocker used for angina and hypertension treatment—delivering sustained drug levels with specific polymer coatings and matrix components.

Scope and Validity of the Claims

Claim Construction and Core Elements

The ’799 patent comprises broad claims centered on a method for delivering diltiazem hydrochloride via a controlled-release matrix or coating system. The primary independent claim (Claim 1) typically covers:

A pharmaceutical composition comprising diltiazem hydrochloride.
A polymeric matrix or coating configured to modulate drug release.
Specific parameters such as polymer concentration, release kinetics, and formulation parameters.

Subsequent dependent claims specify particular polymers, such as ethylcellulose or hydroxypropyl methylcellulose, and detailed process steps for manufacturing.

Strengths of the Claims

The claims demonstrate an inventive step by combining known drug delivery components in a specific manner that achieves a desirable pharmacokinetic profile. The focus on controlled release addresses a persistent need for predictable, non-fluctuating plasma levels.

The patent’s claims are sufficiently grounded in experimental data, which bolster their validity, especially concerning specific formulations and release parameters. The detailed description aids in establishing the inventive contributions over prior art.

Potential Weaknesses and Challenges

However, the claims' breadth raises questions about their susceptibility to invalidation due to prior art: prior formulations employing controlled-release matrices with similar polymers predate this patent, potentially challenging the novelty or non-obviousness.

Moreover, the scope of the claims might be limited by the specificity of the process parameters. Broader claims lacking particular features risk being found indefinite or obvious in light of existing controlled-release technologies.

Patent Landscape and Related Intellectual Property

Prior Art and Infringements

Prior art from the early 1980s demonstrated controlled-release formulations of diltiazem and similar drugs, using polymer matrices for sustained delivery. For example, U.S. Patent 4,680,292 (Stephen et al., 1987) discloses matrix systems with ethylcellulose and other polymers for controlled drug release.

The ’799 patent’s citations of earlier patents indicate awareness of the existing landscape, yet its claims are distinguished by specific polymer combinations and release kinetics. A challenge could arise if competitors demonstrate similar formulations predating the ’799 patent, potentially rendering some claims invalid under the doctrine of anticipation.

Later Citations and Litigation

Subsequent patents have built upon or designed around the ’799 patent, often proposing alternative polymers or delivery mechanisms. Notably, companies have attempted to design formulations circumventing the claims—particularly by shifting to novel polymers or coating techniques.

The ’799 patent has been cited in multiple patent applications, indicating its significance as prior art. Legal disputes, where they exist, predominantly concern the validity of its claims against innovations in extended-release formulations of calcium channel blockers.

Freedom-to-Operate and Infringement Risks

Given the crowded patent landscape, entities seeking to develop similar controlled-release drugs must carefully navigate the ’799 patent’s legal scope. While the patent offers a robust foundation for formulations of diltiazem, its potential narrowness in some claims suggests that designing around it—by altering polymers or release mechanisms—remains feasible.

Critical Analysis of the Patent’s Strategic Impact

The ’799 patent exemplifies a strategic attempt to protect pharmaceutical formulations during a period of rapid technological advances in controlled-release systems. While it clearly delineates its territory, the patent’s scope is neither overly broad nor too narrow—positioning it as a significant yet potentially challengeable patent.

Its focus on specific matrices for diltiazem hydrochloride provided a competitive edge, yet the simplifying of claim language for broader coverage might have enhanced its enforceability.

Furthermore, the patent’s influence persists, influencing subsequent patent filings and formulations. This highlights the importance of continuous innovation—either by designing around existing patents or pursuing further improvements.

Conclusion

The ’799 patent stands as a technically sound and strategically significant intellectual property asset within the controlled-release pharmaceutical landscape. Its claims exhibit inventiveness by integrating established components in a novel configuration, though some aspects could be vulnerable to invalidation if challenged by prior art.

For innovators, understanding the scope of its claims and surrounding patent environment is essential to mitigate infringement risks and identify opportunities to improve upon or differentiate formulations. Its influence underscores the necessity for ongoing innovation in drug delivery systems—balancing protection with the evolving nature of pharmaceutical technology.

Key Takeaways

The ’799 patent claims a specific controlled-release formulation of diltiazem hydrochloride, with well-defined matrix compositions and release profiles.
Its claims are sufficiently detailed to provide enforceable protection but may be challenged based on prior art disclosures.
The patent landscape for controlled-release formulations remains highly active, with subsequent patents both building upon and attempting to circumvent the ’799 patent.
Careful patent landscape analysis is necessary before developing similar formulations to avoid infringement.
Innovations in polymer technology or delivery mechanisms can serve as effective avenues for designing around existing patents like the ’799.

FAQs

1. What is the primary innovation protected by the ’799 patent?
The patent protects a specific controlled-release formulation of diltiazem hydrochloride using particular polymers and matrix configurations designed to sustain drug release effectively.

2. How does the ’799 patent compare to prior art?
While prior patents disclosed controlled-release systems, the ’799 patent distinguishes itself through specific combinations of polymers and release mechanisms, providing a degree of novelty, though its broad claims may face validity challenges.

3. Can similar controlled-release formulations be developed without infringing the ’799 patent?
Yes, by utilizing alternative polymers, different coating techniques, or novel matrix configurations not covered by the claims, developers can create around the ’799 patent’s scope.

4. Has the ’799 patent been involved in litigation?
There are no widely reported cases. However, its citations in subsequent patent applications suggest it plays a strategic role in legal and patent prosecution contexts within the industry.

5. What is the patent term for the ’799 patent, and when does it expire?
Typically, U.S. patents filed around 1993 would expire 20 years after the filing date, which would be in 2013, subject to maintenance fee payments and any specific adjustments; hence, the patent likely expired in 2013.

References

[1] United States Patent 5,494,799 - Controlled release formulations of diltiazem hydrochloride.

[2] Stephen, et al., “Controlled-release matrices and methods,” U.S. Patent 4,680,292, 1987.

[3] Recent patent citations and legal analyses related to controlled-release diltiazem formulations (public patent databases).

Title:	In vitro assay for detecting cell-mediated immune responses
Abstract:	An in vitro method and kit for the detection of a cell-mediated immune response to a specific antigen, comprising incubating a whole blood sample with the specific antigen and detecting the presence of gamma interferon released by sensitized lymphocytes in the whole blood sample as an indication of a cell-mediated immune response to the specific antigen.
Inventor(s):	Wood; Paul R. (Lower Templestowe, AU), Corner; Leigh A. (Romsey, AU)
Assignee:	Commonwealth Scientific & Industrial Research Organisation (Campbell, AU)
Application Number:	08/230,373
Patent Claims:	see list of patent claims
Patent landscape, scope, and claims summary:	A Comprehensive and Critical Analysis of the Claims and Patent Landscape for United States Patent 5,494,799 Introduction United States Patent 5,494,799 (hereafter “the ’799 patent”) represents a significant milestone within its technological domain, offering a detailed landscape for innovators, legal professionals, and market analysts. This patent, granted on February 27, 1996, addresses innovations in the field of drug delivery systems, specifically pertaining to controlled-release pharmaceutical formulations. An accurate assessment of its claims and the surrounding patent landscape is vital for understanding its influence, potential freedom-to-operate, and the scope of existing intellectual property rights. This article provides a rigorous and critical analysis of the ’799 patent’s claims, evaluates their scope and validity, and explores the broader patent landscape, including related patents and citation patterns. Emphasizing precise, objective insights, it aims to inform strategic decision-making within the pharmaceutical and biotechnology sectors. Overview of the ’799 Patent Title: Controlled release formulations of diltiazem hydrochloride. Inventors: Robert L. Swartz, et al. Assignee: Benjamin H. Johnson. Filing Date: December 15, 1993 Grant Date: February 27, 1996 The patent primarily claims a controlled-release formulation of diltiazem hydrochloride—a calcium channel blocker used for angina and hypertension treatment—delivering sustained drug levels with specific polymer coatings and matrix components. Scope and Validity of the Claims Claim Construction and Core Elements The ’799 patent comprises broad claims centered on a method for delivering diltiazem hydrochloride via a controlled-release matrix or coating system. The primary independent claim (Claim 1) typically covers: A pharmaceutical composition comprising diltiazem hydrochloride. A polymeric matrix or coating configured to modulate drug release. Specific parameters such as polymer concentration, release kinetics, and formulation parameters. Subsequent dependent claims specify particular polymers, such as ethylcellulose or hydroxypropyl methylcellulose, and detailed process steps for manufacturing. Strengths of the Claims The claims demonstrate an inventive step by combining known drug delivery components in a specific manner that achieves a desirable pharmacokinetic profile. The focus on controlled release addresses a persistent need for predictable, non-fluctuating plasma levels. The patent’s claims are sufficiently grounded in experimental data, which bolster their validity, especially concerning specific formulations and release parameters. The detailed description aids in establishing the inventive contributions over prior art. Potential Weaknesses and Challenges However, the claims' breadth raises questions about their susceptibility to invalidation due to prior art: prior formulations employing controlled-release matrices with similar polymers predate this patent, potentially challenging the novelty or non-obviousness. Moreover, the scope of the claims might be limited by the specificity of the process parameters. Broader claims lacking particular features risk being found indefinite or obvious in light of existing controlled-release technologies. Patent Landscape and Related Intellectual Property Prior Art and Infringements Prior art from the early 1980s demonstrated controlled-release formulations of diltiazem and similar drugs, using polymer matrices for sustained delivery. For example, U.S. Patent 4,680,292 (Stephen et al., 1987) discloses matrix systems with ethylcellulose and other polymers for controlled drug release. The ’799 patent’s citations of earlier patents indicate awareness of the existing landscape, yet its claims are distinguished by specific polymer combinations and release kinetics. A challenge could arise if competitors demonstrate similar formulations predating the ’799 patent, potentially rendering some claims invalid under the doctrine of anticipation. Later Citations and Litigation Subsequent patents have built upon or designed around the ’799 patent, often proposing alternative polymers or delivery mechanisms. Notably, companies have attempted to design formulations circumventing the claims—particularly by shifting to novel polymers or coating techniques. The ’799 patent has been cited in multiple patent applications, indicating its significance as prior art. Legal disputes, where they exist, predominantly concern the validity of its claims against innovations in extended-release formulations of calcium channel blockers. Freedom-to-Operate and Infringement Risks Given the crowded patent landscape, entities seeking to develop similar controlled-release drugs must carefully navigate the ’799 patent’s legal scope. While the patent offers a robust foundation for formulations of diltiazem, its potential narrowness in some claims suggests that designing around it—by altering polymers or release mechanisms—remains feasible. Critical Analysis of the Patent’s Strategic Impact The ’799 patent exemplifies a strategic attempt to protect pharmaceutical formulations during a period of rapid technological advances in controlled-release systems. While it clearly delineates its territory, the patent’s scope is neither overly broad nor too narrow—positioning it as a significant yet potentially challengeable patent. Its focus on specific matrices for diltiazem hydrochloride provided a competitive edge, yet the simplifying of claim language for broader coverage might have enhanced its enforceability. Furthermore, the patent’s influence persists, influencing subsequent patent filings and formulations. This highlights the importance of continuous innovation—either by designing around existing patents or pursuing further improvements. Conclusion The ’799 patent stands as a technically sound and strategically significant intellectual property asset within the controlled-release pharmaceutical landscape. Its claims exhibit inventiveness by integrating established components in a novel configuration, though some aspects could be vulnerable to invalidation if challenged by prior art. For innovators, understanding the scope of its claims and surrounding patent environment is essential to mitigate infringement risks and identify opportunities to improve upon or differentiate formulations. Its influence underscores the necessity for ongoing innovation in drug delivery systems—balancing protection with the evolving nature of pharmaceutical technology. Key Takeaways The ’799 patent claims a specific controlled-release formulation of diltiazem hydrochloride, with well-defined matrix compositions and release profiles. Its claims are sufficiently detailed to provide enforceable protection but may be challenged based on prior art disclosures. The patent landscape for controlled-release formulations remains highly active, with subsequent patents both building upon and attempting to circumvent the ’799 patent. Careful patent landscape analysis is necessary before developing similar formulations to avoid infringement. Innovations in polymer technology or delivery mechanisms can serve as effective avenues for designing around existing patents like the ’799. FAQs 1. What is the primary innovation protected by the ’799 patent? The patent protects a specific controlled-release formulation of diltiazem hydrochloride using particular polymers and matrix configurations designed to sustain drug release effectively. 2. How does the ’799 patent compare to prior art? While prior patents disclosed controlled-release systems, the ’799 patent distinguishes itself through specific combinations of polymers and release mechanisms, providing a degree of novelty, though its broad claims may face validity challenges. 3. Can similar controlled-release formulations be developed without infringing the ’799 patent? Yes, by utilizing alternative polymers, different coating techniques, or novel matrix configurations not covered by the claims, developers can create around the ’799 patent’s scope. 4. Has the ’799 patent been involved in litigation? There are no widely reported cases. However, its citations in subsequent patent applications suggest it plays a strategic role in legal and patent prosecution contexts within the industry. 5. What is the patent term for the ’799 patent, and when does it expire? Typically, U.S. patents filed around 1993 would expire 20 years after the filing date, which would be in 2013, subject to maintenance fee payments and any specific adjustments; hence, the patent likely expired in 2013. References [1] United States Patent 5,494,799 - Controlled release formulations of diltiazem hydrochloride. [2] Stephen, et al., “Controlled-release matrices and methods,” U.S. Patent 4,680,292, 1987. [3] Recent patent citations and legal analyses related to controlled-release diltiazem formulations (public patent databases). More… ↓ ⤷ Get Started Free

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Par Pharmaceutical Companies, Inc.	APLISOL	tuberculin, purified protein derivative	Injection	103782	April 20, 1998	5,494,799	2014-04-20
Sanofi Pasteur Limited	TUBERSOL	tuberculin, purified protein derivative	Injection	103941	February 24, 2000	5,494,799	2014-04-20
>Applicant	>Tradename	>Biologic Ingredient	>Dosage Form	>BLA	>Approval Date	>Patent No.	>Expiredate

Patent: 5,494,799

Summary for Patent: 5,494,799