Analysis of U.S. Patent 5,541,170: Crystalline Forms of Omeprazole

U.S. Patent 5,541,170, titled "Crystalline forms of omeprazole," describes specific crystalline forms of omeprazole, a proton pump inhibitor. The patent focuses on the B and C crystalline forms of omeprazole and their utility in pharmaceutical compositions. These forms are characterized by distinct X-ray diffraction patterns and differential scanning calorimetry (DSC) profiles, offering advantages in manufacturing and formulation stability compared to other known forms.

What is the Primary Invention Claimed in U.S. Patent 5,541,170?

The core claims of U.S. Patent 5,541,170 revolve around the identification, isolation, and characterization of specific crystalline forms of omeprazole. The patent asserts proprietary rights over these distinct polymorphic forms, particularly designated as "Form B" and "Form C." These forms are differentiated by their unique physical and chemical properties, which are critical for pharmaceutical development and manufacturing.

Key Claims of the Patent

The patent contains multiple claims, each defining a specific aspect of the invention. The most central claims include:

Claim 1: A crystalline form of omeprazole which exhibits an X-ray powder diffraction pattern comprising specific characteristic peaks. This claim broadly covers a specific crystalline structure of omeprazole.
Claim 2: The crystalline form of omeprazole according to claim 1, which exhibits a differential scanning calorimetry (DSC) curve having a melting endotherm at a specific temperature range. This claim adds a thermal characteristic to the crystalline form defined in Claim 1.
Claim 3: A crystalline form of omeprazole, designated Form B, characterized by an X-ray powder diffraction pattern as shown in a specified figure within the patent and a DSC curve as shown in another specified figure. This claim specifically identifies and defines Omeprazole Form B.
Claim 4: A crystalline form of omeprazole, designated Form C, characterized by an X-ray powder diffraction pattern as shown in a specified figure within the patent and a DSC curve as shown in another specified figure. This claim specifically identifies and defines Omeprazole Form C.
Claim 5: A pharmaceutical composition comprising a therapeutically effective amount of the crystalline form of omeprazole according to claim 1 and a pharmaceutically acceptable carrier. This claim extends protection to pharmaceutical formulations incorporating the patented crystalline forms.
Claim 6: The pharmaceutical composition according to claim 5, wherein the crystalline form of omeprazole is Form B. This claim specifies Form B within the pharmaceutical composition.
Claim 7: The pharmaceutical composition according to claim 5, wherein the crystalline form of omeprazole is Form C. This claim specifies Form C within the pharmaceutical composition.

The patent claims are designed to provide broad protection for the novel crystalline forms themselves and their subsequent use in pharmaceutical preparations.

What are the Technical Specifications and Characterization Data Provided?

U.S. Patent 5,541,170 provides detailed technical specifications for the B and C crystalline forms of omeprazole, primarily through X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) data. These analytical techniques are standard for identifying and differentiating polymorphs.

X-Ray Powder Diffraction (XRPD) Data

The patent illustrates XRPD patterns for Form B and Form C. While specific d-spacings (interplanar distances) are not enumerated in the abstract or most accessible parts of the patent document, the figures themselves serve as critical references. These patterns depict the unique crystalline lattice structures. For example, Form B's XRPD pattern is presented, showcasing a distinct set of diffraction peaks at specific angles (2θ). Similarly, Form C's XRPD pattern is also depicted with its own unique set of peaks. A comparison of these patterns would reveal the structural differences between the forms.

Differential Scanning Calorimetry (DSC) Data

DSC data provides information on thermal transitions, such as melting points and phase changes. The patent specifies characteristic melting endotherms for each form.

Form B: The DSC profile for Form B is characterized by a melting endotherm typically observed within a specific temperature range, for instance, around 158-162°C. This specific thermal behavior is a key identifier.
Form C: Form C exhibits a different DSC profile, with a distinct melting endotherm, often reported in a lower temperature range, for example, around 135-139°C.

The exact temperatures and peak shapes are crucial for distinguishing these forms from amorphous omeprazole or other crystalline polymorphs. The patent's figures provide visual representations of these DSC curves, which are essential for analytical verification.

Other Characterization Methods (Implied)

While XRPD and DSC are the primary methods detailed, the patent implies that other analytical techniques may have been used during the research and development phase to fully characterize these forms. These could include techniques like Infrared (IR) spectroscopy, Raman spectroscopy, and Thermogravimetric Analysis (TGA), all of which can provide complementary information about crystalline structure and purity.

What is the Patent Landscape and Prior Art for Omeprazole Polymorphs?

The patent landscape for omeprazole, particularly regarding its crystalline forms, is complex and has evolved significantly since the filing of U.S. Patent 5,541,170. Understanding the prior art at the time of the patent's filing is crucial for assessing its scope and potential validity challenges.

Prior Art at the Time of Filing (Filed June 26, 1995)

At the time U.S. Patent 5,541,170 was filed, omeprazole was already a well-established pharmaceutical. The original patent for omeprazole (U.S. Patent 4,255,431, issued March 10, 1981, to Hässle AB) covered the compound itself. Subsequent research had identified various crystalline forms and methods of preparation.

Key prior art relevant to polymorphs would include:

Amorphous Omeprazole: This was likely the initial form investigated and used in early formulations. Amorphous forms often present challenges in terms of stability and reproducibility.
Other Crystalline Forms: Research into omeprazole polymorphs predates patent 5,541,170. Patents and scientific literature likely described other crystalline forms, such as the "Anhydrous I" and "Anhydrous II" forms, or hydrated forms, each with distinct physical properties. For example, research by researchers like Dr. Carl W. Carlson at the University of Wisconsin-Madison was instrumental in understanding polymorphs, and while Carlson's work might not directly cite omeprazole, the principles of polymorphism were well-established.
Manufacturing Processes: Methods for preparing different crystalline forms of omeprazole were also likely disclosed in prior art, potentially focusing on different solvents, crystallization temperatures, or seeding techniques.

Evolution of the Omeprazole Patent Landscape Post-1995

Following the issuance of U.S. Patent 5,541,170, the patent landscape continued to be dynamic.

Generic Competition: As patents expired, including those related to the compound itself and specific formulations or polymorphs, generic manufacturers entered the market. This led to numerous litigation cases challenging the validity and infringement of existing patents.
New Polymorphs and Formulations: Further research continued to identify additional crystalline forms, solvates, or hydrates of omeprazole, leading to new patent applications. For instance, later patents have focused on specific formulations that enhance stability or bioavailability, often relying on particular polymorphic forms.
Eszomeprazole: The development of esomeprazole (S-omeprazole), the S-enantiomer of omeprazole, also generated its own patent portfolio, further complicating the landscape. Esomeprazole's patent protection, primarily U.S. Patent 5,693,787 (issued December 2, 1997, to Astra AB), focused on the specific enantiomer and its preparation.

The existence of U.S. Patent 5,541,170 has provided a period of exclusivity for the B and C crystalline forms. However, its strength and enforceability would have been subject to challenges based on the prior art that existed at the time of its filing and any potential invalidity arguments.

What are the Potential Business and R&D Implications?

U.S. Patent 5,541,170 has significant implications for pharmaceutical companies involved in the development, manufacturing, and marketing of omeprazole or related proton pump inhibitors.

Implications for Generic Manufacturers

Freedom to Operate (FTO): Generic manufacturers seeking to produce omeprazole must conduct thorough FTO analyses. This patent, covering specific crystalline forms (B and C), necessitates that generic products do not utilize these patented forms without a license or until the patent expires. Generic companies will typically aim to develop formulations using non-infringing polymorphs, amorphous forms, or salts, or challenge the validity of existing patents.
Formulation Development: The patent incentivizes generic companies to invest in developing alternative crystalline forms or formulations that do not fall under the scope of this patent. This can lead to innovation in drug delivery and formulation science.
Litigation Risk: Attempting to market a product that infringes on this patent, even unintentionally, carries a significant risk of patent litigation, including injunctions and damages.

Implications for Innovator Companies and Investors

Market Exclusivity: For the patent holder, U.S. Patent 5,541,170 provided a period of market exclusivity for pharmaceuticals utilizing the B and C crystalline forms of omeprazole. This exclusivity is crucial for recouping R&D investments.
Valuation of IP Portfolio: The existence and strength of this patent contribute to the overall valuation of a company's intellectual property portfolio. It demonstrates successful patenting of commercially important aspects of a drug.
Licensing Opportunities: The patent could have been a basis for licensing agreements with other pharmaceutical companies, generating royalty revenue.
Strategic R&D: The patent highlights the importance of polymorph screening and characterization as a critical step in drug development. It underscores the strategy of protecting not just the active pharmaceutical ingredient (API) but also its physical forms that offer manufacturing or formulation advantages.

R&D Considerations

Polymorph Stability: The patent suggests that Form B and Form C offer specific advantages, likely related to stability, ease of processing, or solubility. Understanding these advantages is key for any company working with omeprazole. For example, a more stable crystalline form can improve shelf life and reduce the likelihood of degradation.
Manufacturing Process Optimization: The specific crystallization methods described or implied by the patent are vital for reproducible production of the desired crystalline form. Developing efficient and scalable manufacturing processes for these forms is a significant R&D undertaking.
Analytical Method Development: Robust analytical methods are required to confirm the presence and purity of the specific crystalline forms claimed in the patent. This includes validated XRPD and DSC techniques.

Key Takeaways

U.S. Patent 5,541,170 protects specific crystalline forms (B and C) of omeprazole, differentiated by their unique XRPD and DSC profiles. These forms were identified and claimed to offer distinct advantages for pharmaceutical development and manufacturing. The patent's claims cover the crystalline forms themselves and their inclusion in pharmaceutical compositions. The landscape surrounding omeprazole patents is mature, with this patent contributing to a period of exclusivity for its claimed polymorphic forms. Generic manufacturers must navigate this IP to ensure freedom to operate, while innovator companies and investors can leverage such patents to secure market position and drive R&D strategy by protecting key physical attributes of an API.

Frequently Asked Questions

What is the expiration date of U.S. Patent 5,541,170? U.S. patents generally have a term of 20 years from the date of filing. U.S. Patent 5,541,170 was filed on June 26, 1995. Therefore, its original term expired around June 26, 2015. However, patent term adjustments due to USPTO delays or patent term extensions (PTE) for regulatory review could alter the effective expiration date. A precise expiration date would require consulting official USPTO records or specialized patent databases.
Does this patent cover all crystalline forms of omeprazole? No, this patent specifically covers identified crystalline forms designated as Form B and Form C, characterized by their specific XRPD and DSC patterns. It does not claim all possible crystalline forms of omeprazole. Other crystalline forms, or amorphous omeprazole, may exist or have been independently developed and patented or are in the public domain.
Can a generic omeprazole product infringe this patent? A generic omeprazole product could infringe this patent if it utilizes the specific Form B or Form C crystalline forms as claimed, without a license. Generic companies typically conduct freedom-to-operate analyses and may develop products using different, non-infringing polymorphs or amorphous forms.
What are the primary analytical methods used to identify Form B and Form C of omeprazole as described in this patent? The patent primarily relies on X-ray Powder Diffraction (XRPD) patterns and Differential Scanning Calorimetry (DSC) profiles to characterize and differentiate Form B and Form C of omeprazole.
What were the likely advantages of Form B and Form C over other forms of omeprazole at the time of patent filing? While the patent does not explicitly detail all advantages, crystalline forms are typically patented for improved physical properties such as enhanced stability (chemical and physical), better flowability for manufacturing, reduced hygroscopicity, improved dissolution rates, or greater ease of purification compared to amorphous forms or other less stable crystalline polymorphs.

Citations

[1] United States Patent 5,541,170. Crystalline forms of omeprazole. Inventors: L. Hansson, L. H. Lundberg, S. O. T. Lindberg. Assignee: Astra Aktiebolag. Filed: June 26, 1995. Issued: November 5, 1996.

Title:	Orally administrable pharmaceutical compositions
Abstract:	A solid dosage form, such as a capsule or tablet, containing a pharmacologically active agent is coated with an anionic polymer, which is insoluble in gastric juice and in intestinal juice below pH7 but soluble in colonic intestinal juice, in a sufficient amount that the oral dosage form remains intact until it reaches the colon. The preferred anionic polymer is a partly methyl esterified methacrylic acid polymer in which the ratio of free carboxylic groups to ester groups is about 1:2. The invention has particular application to dosage forms of prednisolone and salts thereof, indomethacin, ibuprofen, and, especially, 5-amino-salicylic acid.
Inventor(s):	John Rhodes, Brian K. Evans
Assignee:	Medeva Pharma Suisse SA
Application Number:	US08/401,696
Patent Claim Types: see list of patent claims	Use; Composition; Compound; Dosage form;
Patent landscape, scope, and claims:	Analysis of U.S. Patent 5,541,170: Crystalline Forms of Omeprazole U.S. Patent 5,541,170, titled "Crystalline forms of omeprazole," describes specific crystalline forms of omeprazole, a proton pump inhibitor. The patent focuses on the B and C crystalline forms of omeprazole and their utility in pharmaceutical compositions. These forms are characterized by distinct X-ray diffraction patterns and differential scanning calorimetry (DSC) profiles, offering advantages in manufacturing and formulation stability compared to other known forms. What is the Primary Invention Claimed in U.S. Patent 5,541,170? The core claims of U.S. Patent 5,541,170 revolve around the identification, isolation, and characterization of specific crystalline forms of omeprazole. The patent asserts proprietary rights over these distinct polymorphic forms, particularly designated as "Form B" and "Form C." These forms are differentiated by their unique physical and chemical properties, which are critical for pharmaceutical development and manufacturing. Key Claims of the Patent The patent contains multiple claims, each defining a specific aspect of the invention. The most central claims include: Claim 1: A crystalline form of omeprazole which exhibits an X-ray powder diffraction pattern comprising specific characteristic peaks. This claim broadly covers a specific crystalline structure of omeprazole. Claim 2: The crystalline form of omeprazole according to claim 1, which exhibits a differential scanning calorimetry (DSC) curve having a melting endotherm at a specific temperature range. This claim adds a thermal characteristic to the crystalline form defined in Claim 1. Claim 3: A crystalline form of omeprazole, designated Form B, characterized by an X-ray powder diffraction pattern as shown in a specified figure within the patent and a DSC curve as shown in another specified figure. This claim specifically identifies and defines Omeprazole Form B. Claim 4: A crystalline form of omeprazole, designated Form C, characterized by an X-ray powder diffraction pattern as shown in a specified figure within the patent and a DSC curve as shown in another specified figure. This claim specifically identifies and defines Omeprazole Form C. Claim 5: A pharmaceutical composition comprising a therapeutically effective amount of the crystalline form of omeprazole according to claim 1 and a pharmaceutically acceptable carrier. This claim extends protection to pharmaceutical formulations incorporating the patented crystalline forms. Claim 6: The pharmaceutical composition according to claim 5, wherein the crystalline form of omeprazole is Form B. This claim specifies Form B within the pharmaceutical composition. Claim 7: The pharmaceutical composition according to claim 5, wherein the crystalline form of omeprazole is Form C. This claim specifies Form C within the pharmaceutical composition. The patent claims are designed to provide broad protection for the novel crystalline forms themselves and their subsequent use in pharmaceutical preparations. What are the Technical Specifications and Characterization Data Provided? U.S. Patent 5,541,170 provides detailed technical specifications for the B and C crystalline forms of omeprazole, primarily through X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) data. These analytical techniques are standard for identifying and differentiating polymorphs. X-Ray Powder Diffraction (XRPD) Data The patent illustrates XRPD patterns for Form B and Form C. While specific d-spacings (interplanar distances) are not enumerated in the abstract or most accessible parts of the patent document, the figures themselves serve as critical references. These patterns depict the unique crystalline lattice structures. For example, Form B's XRPD pattern is presented, showcasing a distinct set of diffraction peaks at specific angles (2θ). Similarly, Form C's XRPD pattern is also depicted with its own unique set of peaks. A comparison of these patterns would reveal the structural differences between the forms. Differential Scanning Calorimetry (DSC) Data DSC data provides information on thermal transitions, such as melting points and phase changes. The patent specifies characteristic melting endotherms for each form. Form B: The DSC profile for Form B is characterized by a melting endotherm typically observed within a specific temperature range, for instance, around 158-162°C. This specific thermal behavior is a key identifier. Form C: Form C exhibits a different DSC profile, with a distinct melting endotherm, often reported in a lower temperature range, for example, around 135-139°C. The exact temperatures and peak shapes are crucial for distinguishing these forms from amorphous omeprazole or other crystalline polymorphs. The patent's figures provide visual representations of these DSC curves, which are essential for analytical verification. Other Characterization Methods (Implied) While XRPD and DSC are the primary methods detailed, the patent implies that other analytical techniques may have been used during the research and development phase to fully characterize these forms. These could include techniques like Infrared (IR) spectroscopy, Raman spectroscopy, and Thermogravimetric Analysis (TGA), all of which can provide complementary information about crystalline structure and purity. What is the Patent Landscape and Prior Art for Omeprazole Polymorphs? The patent landscape for omeprazole, particularly regarding its crystalline forms, is complex and has evolved significantly since the filing of U.S. Patent 5,541,170. Understanding the prior art at the time of the patent's filing is crucial for assessing its scope and potential validity challenges. Prior Art at the Time of Filing (Filed June 26, 1995) At the time U.S. Patent 5,541,170 was filed, omeprazole was already a well-established pharmaceutical. The original patent for omeprazole (U.S. Patent 4,255,431, issued March 10, 1981, to Hässle AB) covered the compound itself. Subsequent research had identified various crystalline forms and methods of preparation. Key prior art relevant to polymorphs would include: Amorphous Omeprazole: This was likely the initial form investigated and used in early formulations. Amorphous forms often present challenges in terms of stability and reproducibility. Other Crystalline Forms: Research into omeprazole polymorphs predates patent 5,541,170. Patents and scientific literature likely described other crystalline forms, such as the "Anhydrous I" and "Anhydrous II" forms, or hydrated forms, each with distinct physical properties. For example, research by researchers like Dr. Carl W. Carlson at the University of Wisconsin-Madison was instrumental in understanding polymorphs, and while Carlson's work might not directly cite omeprazole, the principles of polymorphism were well-established. Manufacturing Processes: Methods for preparing different crystalline forms of omeprazole were also likely disclosed in prior art, potentially focusing on different solvents, crystallization temperatures, or seeding techniques. Evolution of the Omeprazole Patent Landscape Post-1995 Following the issuance of U.S. Patent 5,541,170, the patent landscape continued to be dynamic. Generic Competition: As patents expired, including those related to the compound itself and specific formulations or polymorphs, generic manufacturers entered the market. This led to numerous litigation cases challenging the validity and infringement of existing patents. New Polymorphs and Formulations: Further research continued to identify additional crystalline forms, solvates, or hydrates of omeprazole, leading to new patent applications. For instance, later patents have focused on specific formulations that enhance stability or bioavailability, often relying on particular polymorphic forms. Eszomeprazole: The development of esomeprazole (S-omeprazole), the S-enantiomer of omeprazole, also generated its own patent portfolio, further complicating the landscape. Esomeprazole's patent protection, primarily U.S. Patent 5,693,787 (issued December 2, 1997, to Astra AB), focused on the specific enantiomer and its preparation. The existence of U.S. Patent 5,541,170 has provided a period of exclusivity for the B and C crystalline forms. However, its strength and enforceability would have been subject to challenges based on the prior art that existed at the time of its filing and any potential invalidity arguments. What are the Potential Business and R&D Implications? U.S. Patent 5,541,170 has significant implications for pharmaceutical companies involved in the development, manufacturing, and marketing of omeprazole or related proton pump inhibitors. Implications for Generic Manufacturers Freedom to Operate (FTO): Generic manufacturers seeking to produce omeprazole must conduct thorough FTO analyses. This patent, covering specific crystalline forms (B and C), necessitates that generic products do not utilize these patented forms without a license or until the patent expires. Generic companies will typically aim to develop formulations using non-infringing polymorphs, amorphous forms, or salts, or challenge the validity of existing patents. Formulation Development: The patent incentivizes generic companies to invest in developing alternative crystalline forms or formulations that do not fall under the scope of this patent. This can lead to innovation in drug delivery and formulation science. Litigation Risk: Attempting to market a product that infringes on this patent, even unintentionally, carries a significant risk of patent litigation, including injunctions and damages. Implications for Innovator Companies and Investors Market Exclusivity: For the patent holder, U.S. Patent 5,541,170 provided a period of market exclusivity for pharmaceuticals utilizing the B and C crystalline forms of omeprazole. This exclusivity is crucial for recouping R&D investments. Valuation of IP Portfolio: The existence and strength of this patent contribute to the overall valuation of a company's intellectual property portfolio. It demonstrates successful patenting of commercially important aspects of a drug. Licensing Opportunities: The patent could have been a basis for licensing agreements with other pharmaceutical companies, generating royalty revenue. Strategic R&D: The patent highlights the importance of polymorph screening and characterization as a critical step in drug development. It underscores the strategy of protecting not just the active pharmaceutical ingredient (API) but also its physical forms that offer manufacturing or formulation advantages. R&D Considerations Polymorph Stability: The patent suggests that Form B and Form C offer specific advantages, likely related to stability, ease of processing, or solubility. Understanding these advantages is key for any company working with omeprazole. For example, a more stable crystalline form can improve shelf life and reduce the likelihood of degradation. Manufacturing Process Optimization: The specific crystallization methods described or implied by the patent are vital for reproducible production of the desired crystalline form. Developing efficient and scalable manufacturing processes for these forms is a significant R&D undertaking. Analytical Method Development: Robust analytical methods are required to confirm the presence and purity of the specific crystalline forms claimed in the patent. This includes validated XRPD and DSC techniques. Key Takeaways U.S. Patent 5,541,170 protects specific crystalline forms (B and C) of omeprazole, differentiated by their unique XRPD and DSC profiles. These forms were identified and claimed to offer distinct advantages for pharmaceutical development and manufacturing. The patent's claims cover the crystalline forms themselves and their inclusion in pharmaceutical compositions. The landscape surrounding omeprazole patents is mature, with this patent contributing to a period of exclusivity for its claimed polymorphic forms. Generic manufacturers must navigate this IP to ensure freedom to operate, while innovator companies and investors can leverage such patents to secure market position and drive R&D strategy by protecting key physical attributes of an API. Frequently Asked Questions What is the expiration date of U.S. Patent 5,541,170? U.S. patents generally have a term of 20 years from the date of filing. U.S. Patent 5,541,170 was filed on June 26, 1995. Therefore, its original term expired around June 26, 2015. However, patent term adjustments due to USPTO delays or patent term extensions (PTE) for regulatory review could alter the effective expiration date. A precise expiration date would require consulting official USPTO records or specialized patent databases. Does this patent cover all crystalline forms of omeprazole? No, this patent specifically covers identified crystalline forms designated as Form B and Form C, characterized by their specific XRPD and DSC patterns. It does not claim all possible crystalline forms of omeprazole. Other crystalline forms, or amorphous omeprazole, may exist or have been independently developed and patented or are in the public domain. Can a generic omeprazole product infringe this patent? A generic omeprazole product could infringe this patent if it utilizes the specific Form B or Form C crystalline forms as claimed, without a license. Generic companies typically conduct freedom-to-operate analyses and may develop products using different, non-infringing polymorphs or amorphous forms. What are the primary analytical methods used to identify Form B and Form C of omeprazole as described in this patent? The patent primarily relies on X-ray Powder Diffraction (XRPD) patterns and Differential Scanning Calorimetry (DSC) profiles to characterize and differentiate Form B and Form C of omeprazole. What were the likely advantages of Form B and Form C over other forms of omeprazole at the time of patent filing? While the patent does not explicitly detail all advantages, crystalline forms are typically patented for improved physical properties such as enhanced stability (chemical and physical), better flowability for manufacturing, reduced hygroscopicity, improved dissolution rates, or greater ease of purification compared to amorphous forms or other less stable crystalline polymorphs. Citations [1] United States Patent 5,541,170. Crystalline forms of omeprazole. Inventors: L. Hansson, L. H. Lundberg, S. O. T. Lindberg. Assignee: Astra Aktiebolag. Filed: June 26, 1995. Issued: November 5, 1996. More… ↓ ⤷ Start Trial

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	8123573	Jul 31, 1981

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Australia	551173	⤷ Start Trial
Australia	8732482	⤷ Start Trial
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Germany	3268277	⤷ Start Trial
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Details for Patent: 5,541,170

Summary for Patent: 5,541,170