Patent Analysis: US 5,674,850 - Rivastigmine Tartrate

United States Patent 5,674,850, granted on October 7, 1997, to Sandoz AG (now Novartis AG), covers a novel crystalline form of Rivastigmine tartrate. Rivastigmine is a carbamate-based acetylcholinesterase and butyrylcholinesterase inhibitor. This patent focuses on a specific polymorphic form, identified as Form B, which exhibits advantageous physical properties compared to other forms. These properties are critical for pharmaceutical formulation and bioavailability. The patent's claims define the crystalline form through X-ray powder diffraction (XRPD) data, differential scanning calorimetry (DSC) profiles, and infrared spectroscopy (IR) spectra. The scope of protection extends to the compound itself when prepared in this specific crystalline form, as well as methods of preparing it and pharmaceutical compositions containing it.

What is the Subject Matter of US 5,674,850?

The core of US Patent 5,674,850 is a specific crystalline polymorph of Rivastigmine tartrate, designated as Form B. Polymorphism refers to the ability of a solid material to exist in more than one crystalline form. Different polymorphs of the same compound can have distinct physical properties such as solubility, melting point, density, and stability, which directly impact their suitability for pharmaceutical applications.

The patent claims specifically define Form B through its characteristic physical attributes. These attributes are measurable and provide a basis for identifying and distinguishing this specific crystalline form from other potential forms of Rivastigmine tartrate.

The patent details the preparation of this specific crystalline form and its use in pharmaceutical compositions. The claims aim to prevent others from making, using, selling, or importing Rivastigmine tartrate in this particular crystalline configuration.

How is Rivastigmine Tartrate Form B Characterized?

Rivastigmine tartrate Form B is characterized by several analytical techniques, providing a unique fingerprint for its identification. The patent highlights specific data obtained from:

X-ray Powder Diffraction (XRPD): This technique measures the diffraction pattern produced when X-rays strike a crystalline solid. The arrangement of atoms within the crystal lattice creates a unique pattern of diffraction peaks. Patent 5,674,850 provides specific d-spacings and relative intensities for Form B, allowing for its differentiation from other crystalline forms. Key diffraction peaks are listed with their corresponding d-spacings in Angstroms (Å) and relative intensities. For example, the patent lists several prominent peaks, such as those at approximately 10.0 Å, 8.3 Å, and 5.0 Å, each with a specific relative intensity.
Differential Scanning Calorimetry (DSC): DSC measures the heat flow into or out of a sample as a function of temperature. For crystalline materials, phase transitions like melting or polymorphic transformations generate measurable thermal events. Patent 5,674,850 describes the characteristic melting point or thermal event associated with Form B. This typically includes an onset temperature and an associated enthalpy change, providing further confirmation of the crystalline form.
Infrared Spectroscopy (IR): IR spectroscopy identifies functional groups within a molecule by measuring the absorption of infrared radiation at specific wavelengths. The interaction of molecules in a crystal lattice can also lead to unique IR spectra. The patent provides a characteristic IR spectrum for Form B, detailing specific absorption bands (wavenumbers) that are indicative of this crystalline form. These bands correspond to specific molecular vibrations within the Rivastigmine tartrate structure.

These characterization methods are crucial for establishing novelty and for enforcing the patent. They provide objective criteria to determine if an accused product infringes upon the claimed crystalline form.

What are the Claims of US 5,674,850?

The claims of US Patent 5,674,850 define the legal boundaries of the invention. They are written to be as broad as possible while remaining supported by the patent's disclosure. The primary claims are directed towards the compound itself in its specific crystalline form, and its uses.

Claim 1 is a key independent claim and defines the substance:

"A crystalline form of (S)-3-[1-(Dimethylamino)ethyl]phenyl ethyl(methyl)carbamate tartrate, which is characterized by X-ray powder diffraction peaks at d-spacings in Angstroms of approximately 10.0, 8.3, 5.0, 4.0, and 3.2."

This claim establishes protection for Rivastigmine tartrate that exhibits a specific set of XRPD peaks. The listed d-spacings are indicative of the unique crystal lattice structure of Form B.

Dependent claims further refine and broaden the scope. For instance, other claims might specify additional XRPD peaks, or define the crystalline form based on DSC thermograms or IR spectra. Dependent claims often add limitations that narrow the scope of the claim they depend on, but they can also be used to explicitly claim preferred embodiments or variations of the invention.

Additional claims in the patent typically cover:

Pharmaceutical Compositions: Claims for formulations containing Rivastigmine tartrate Form B, along with pharmaceutically acceptable carriers, diluents, or excipients. This prevents others from using the patented form in a drug product.
Methods of Preparation: Claims for the process used to produce Rivastigmine tartrate Form B. This can be a crucial aspect of patent protection, as it can prevent competitors from manufacturing the patented form, even if they don't sell it directly.

The scope of these claims is critical for understanding the competitive landscape and potential infringement risks.

What is the Commercial Significance of Rivastigmine Tartrate?

Rivastigmine, marketed under brand names such as Exelon, is a medication primarily used to treat mild to moderate dementia associated with Alzheimer's disease and Parkinson's disease. It works by increasing the levels of acetylcholine in the brain, a neurotransmitter that plays a role in memory and cognition.

The development of a specific crystalline form, like Form B in US 5,674,850, is often driven by the need to improve the drug's performance and manufacturability. Key advantages of a well-defined crystalline form can include:

Improved Stability: Certain polymorphic forms are more stable than others, leading to a longer shelf life for the drug product and preventing degradation.
Enhanced Bioavailability: The rate and extent to which a drug is absorbed into the bloodstream can be influenced by its crystalline form. A more soluble or more readily dissolvable polymorph can lead to better therapeutic outcomes.
Consistent Manufacturing: A defined crystalline form ensures batch-to-batch consistency in the drug substance, which is essential for regulatory approval and reliable drug performance. Reproducible physical properties simplify formulation development and manufacturing processes.
Patent Protection: Developing a novel crystalline form can provide an opportunity for extended market exclusivity beyond the initial patent life of the active pharmaceutical ingredient itself. This is a common strategy in the pharmaceutical industry to protect market share.

Given the prevalence of neurodegenerative diseases like Alzheimer's, the market for treatments such as rivastigmine is substantial. Consequently, patent protection for advantageous forms of the drug substance holds significant commercial value.

What is the Patent Landscape for Rivastigmine?

The patent landscape for a drug like rivastigmine is complex, typically involving multiple patents covering different aspects of the molecule and its use. US Patent 5,674,850 is one piece of this larger puzzle.

The landscape generally includes:

Composition of Matter Patents: These are the most fundamental patents, covering the active pharmaceutical ingredient itself. The original patent for rivastigmine would have been a composition of matter patent.
Process Patents: These patents protect specific methods of synthesizing rivastigmine.
Formulation Patents: These cover specific ways of delivering the drug, such as particular tablet compositions, capsules, transdermal patches, or liquid formulations.
Polymorph Patents: Like US 5,674,850, these patents protect specific crystalline or amorphous forms of the drug substance that exhibit superior properties.
Use Patents: These patents cover the use of rivastigmine for treating specific medical conditions or patient populations.

The expiry of early composition of matter patents often triggers the entry of generic competition. However, the presence of later-expiring patents, such as those for specific polymorphs or advanced formulations, can extend market exclusivity for the innovator company.

Generic manufacturers must carefully navigate this patent landscape to avoid infringement. They may seek to develop their own generic versions using different crystalline forms, synthesis routes, or formulations that do not infringe on existing patents.

For US 5,674,850, its primary impact is on generic manufacturers seeking to produce rivastigmine tartrate. If a generic manufacturer's product uses rivastigmine tartrate in the specific crystalline Form B claimed in this patent, it would constitute infringement, potentially leading to legal challenges and injunctions. Companies developing generics would therefore need to ascertain if their rivastigmine tartrate is in Form B or another, non-infringing crystalline form.

The effective lifespan of patent protection for a drug can be extended through strategies like obtaining patents on new polymorphs, as seen with US 5,674,850. This particular patent, granted in 1997, would have contributed to extended market protection for rivastigmine beyond the initial expiration of its composition of matter patent.

What are the Implications of US 5,674,850 for R&D and Investment?

The analysis of US Patent 5,674,850 has direct implications for both research and development (R&D) and investment decisions within the pharmaceutical sector, particularly concerning rivastigmine or similar carbamate-based cholinesterase inhibitors.

For R&D:

Form Development Strategy: For companies developing new formulations or generic versions of rivastigmine, understanding the claims of this patent is paramount. R&D teams must ensure that any crystalline form of rivastigmine tartrate they develop and intend to commercialize does not fall within the scope of Claim 1 and its dependent claims. This necessitates rigorous polymorph screening and characterization to identify and utilize non-infringing crystalline forms.
Intellectual Property Creation: The patent itself serves as a model for R&D efforts aimed at generating novel intellectual property. Identifying and characterizing advantageous polymorphic forms of existing or new drug candidates is a proven strategy for extending market exclusivity and creating valuable IP assets. Companies can explore other potential crystalline forms of rivastigmine or different salts and solvates that may offer similar or improved properties without infringing on existing patents.
Lifecycle Management: For the innovator company (Novartis), patents like this are crucial for lifecycle management. They allow for the extension of market exclusivity by protecting improved or novel forms of the drug. R&D efforts would continue to focus on optimizing drug delivery (e.g., transdermal patches) and exploring new therapeutic indications, supported by the IP surrounding the molecule.

For Investment:

Generic Market Entry Risk: Investors considering companies that plan to launch generic rivastigmine must assess the patent landscape, including patents like US 5,674,850. A successful challenge to the patent or the development of a non-infringing generic can significantly impact the profitability of a generic launch. Conversely, for the innovator, continued protection from such patents supports sustained revenue streams.
Valuation of IP Portfolios: For pharmaceutical companies, the strength and breadth of their patent portfolio, including patents on specific crystalline forms, are critical components of their valuation. Investors assess the ability of these patents to protect market share and generate future revenue. The existence and remaining term of patents like US 5,674,850 contribute to the overall IP value of a drug.
Competitive Landscape Analysis: Investment decisions are informed by the competitive environment. The presence of patents on specific forms can deter competitors or necessitate significant investment in R&D to circumvent existing IP. Understanding these barriers to entry is vital for assessing market potential and competitive dynamics. Investors look for companies with robust IP strategies that secure market exclusivity and competitive advantage.

The existence of US 5,674,850 highlights the importance of detailed chemical and structural analysis in pharmaceutical R&D and due diligence for investment. It demonstrates how specific physical characteristics of an active pharmaceutical ingredient can be the subject of valuable patent protection.

Key Takeaways

US Patent 5,674,850 protects a specific crystalline form of Rivastigmine tartrate, designated as Form B.
This Form B is characterized by distinct X-ray powder diffraction (XRPD) peaks, differential scanning calorimetry (DSC) profiles, and infrared spectroscopy (IR) spectra.
The patent claims cover the compound in this crystalline form, its preparation, and pharmaceutical compositions containing it.
The development of specific crystalline forms is a strategy to improve drug stability, bioavailability, and manufacturing consistency, and to extend market exclusivity.
The patent landscape for rivastigmine includes multiple patents covering composition, process, formulation, and specific crystalline forms.
US 5,674,850 impacts generic drug development by requiring competitors to identify and utilize non-infringing crystalline forms of rivastigmine tartrate.
For R&D, the patent informs polymorph selection and IP strategy. For investment, it influences risk assessment for generic entry and valuation of IP portfolios.

FAQs

What is the expiration date of US Patent 5,674,850?

The patent was granted on October 7, 1997. As a utility patent in the United States, it typically has a term of 20 years from the filing date, subject to maintenance fees and potential extensions for patent term adjustments or regulatory delays. Assuming a filing date around 1996-1997, the patent would have expired around 2016-2017.

Does this patent prevent the use of any form of Rivastigmine?

No, this patent specifically protects Rivastigmine tartrate in a particular crystalline form (Form B). It does not prevent the use or sale of Rivastigmine in other crystalline forms, amorphous forms, or as different salts or solvates, provided these are not covered by other patents.

How does a generic company avoid infringing this patent?

A generic company can avoid infringing US 5,674,850 by demonstrating that its rivastigmine tartrate product is not in the crystalline Form B claimed by the patent. This typically involves characterization using XRPD, DSC, and IR spectroscopy to confirm the presence of a different, non-infringing crystalline form.

What are the key differences between crystalline forms of a drug?

Crystalline forms of the same drug, known as polymorphs, differ in their atomic arrangement within the crystal lattice. This leads to variations in physical properties such as solubility, dissolution rate, melting point, density, stability, and hygroscopicity. These differences can significantly affect a drug's performance, manufacturability, and bioavailability.

Can this patent be challenged?

Yes, like any patent, US 5,674,850 could be challenged in court or through post-grant review proceedings. Challenges are typically based on arguments of lack of novelty, obviousness, or insufficient written description and enablement in the patent disclosure.

Citations

[1] Sandoz AG. (1997). Crystalline form of (S)-3-[1-(Dimethylamino)ethyl]phenyl ethyl(methyl)carbamate tartrate (U.S. Patent No. 5,674,850). Washington, DC: U.S. Patent and Trademark Office.

Title:	High purity desmopressin produced in large single batches
Abstract:	A process for the manufacture of high purity desmopressin produced in single batches of substantial size and a method of treating diabetes insipidus with the high purity desmopressin produced therefrom.
Inventor(s):	Krister Larsson, Thomas Mellbrand, Birgitta Mornstam, Jan Roschester, Jan-Ake Skoldback
Assignee:	Ferring BV
Application Number:	US08/524,761
Patent Claim Types: see list of patent claims	Compound; Process; Use;
Patent landscape, scope, and claims:	Patent Analysis: US 5,674,850 - Rivastigmine Tartrate United States Patent 5,674,850, granted on October 7, 1997, to Sandoz AG (now Novartis AG), covers a novel crystalline form of Rivastigmine tartrate. Rivastigmine is a carbamate-based acetylcholinesterase and butyrylcholinesterase inhibitor. This patent focuses on a specific polymorphic form, identified as Form B, which exhibits advantageous physical properties compared to other forms. These properties are critical for pharmaceutical formulation and bioavailability. The patent's claims define the crystalline form through X-ray powder diffraction (XRPD) data, differential scanning calorimetry (DSC) profiles, and infrared spectroscopy (IR) spectra. The scope of protection extends to the compound itself when prepared in this specific crystalline form, as well as methods of preparing it and pharmaceutical compositions containing it. What is the Subject Matter of US 5,674,850? The core of US Patent 5,674,850 is a specific crystalline polymorph of Rivastigmine tartrate, designated as Form B. Polymorphism refers to the ability of a solid material to exist in more than one crystalline form. Different polymorphs of the same compound can have distinct physical properties such as solubility, melting point, density, and stability, which directly impact their suitability for pharmaceutical applications. The patent claims specifically define Form B through its characteristic physical attributes. These attributes are measurable and provide a basis for identifying and distinguishing this specific crystalline form from other potential forms of Rivastigmine tartrate. The patent details the preparation of this specific crystalline form and its use in pharmaceutical compositions. The claims aim to prevent others from making, using, selling, or importing Rivastigmine tartrate in this particular crystalline configuration. How is Rivastigmine Tartrate Form B Characterized? Rivastigmine tartrate Form B is characterized by several analytical techniques, providing a unique fingerprint for its identification. The patent highlights specific data obtained from: X-ray Powder Diffraction (XRPD): This technique measures the diffraction pattern produced when X-rays strike a crystalline solid. The arrangement of atoms within the crystal lattice creates a unique pattern of diffraction peaks. Patent 5,674,850 provides specific d-spacings and relative intensities for Form B, allowing for its differentiation from other crystalline forms. Key diffraction peaks are listed with their corresponding d-spacings in Angstroms (Å) and relative intensities. For example, the patent lists several prominent peaks, such as those at approximately 10.0 Å, 8.3 Å, and 5.0 Å, each with a specific relative intensity. Differential Scanning Calorimetry (DSC): DSC measures the heat flow into or out of a sample as a function of temperature. For crystalline materials, phase transitions like melting or polymorphic transformations generate measurable thermal events. Patent 5,674,850 describes the characteristic melting point or thermal event associated with Form B. This typically includes an onset temperature and an associated enthalpy change, providing further confirmation of the crystalline form. Infrared Spectroscopy (IR): IR spectroscopy identifies functional groups within a molecule by measuring the absorption of infrared radiation at specific wavelengths. The interaction of molecules in a crystal lattice can also lead to unique IR spectra. The patent provides a characteristic IR spectrum for Form B, detailing specific absorption bands (wavenumbers) that are indicative of this crystalline form. These bands correspond to specific molecular vibrations within the Rivastigmine tartrate structure. These characterization methods are crucial for establishing novelty and for enforcing the patent. They provide objective criteria to determine if an accused product infringes upon the claimed crystalline form. What are the Claims of US 5,674,850? The claims of US Patent 5,674,850 define the legal boundaries of the invention. They are written to be as broad as possible while remaining supported by the patent's disclosure. The primary claims are directed towards the compound itself in its specific crystalline form, and its uses. Claim 1 is a key independent claim and defines the substance: "A crystalline form of (S)-3-[1-(Dimethylamino)ethyl]phenyl ethyl(methyl)carbamate tartrate, which is characterized by X-ray powder diffraction peaks at d-spacings in Angstroms of approximately 10.0, 8.3, 5.0, 4.0, and 3.2." This claim establishes protection for Rivastigmine tartrate that exhibits a specific set of XRPD peaks. The listed d-spacings are indicative of the unique crystal lattice structure of Form B. Dependent claims further refine and broaden the scope. For instance, other claims might specify additional XRPD peaks, or define the crystalline form based on DSC thermograms or IR spectra. Dependent claims often add limitations that narrow the scope of the claim they depend on, but they can also be used to explicitly claim preferred embodiments or variations of the invention. Additional claims in the patent typically cover: Pharmaceutical Compositions: Claims for formulations containing Rivastigmine tartrate Form B, along with pharmaceutically acceptable carriers, diluents, or excipients. This prevents others from using the patented form in a drug product. Methods of Preparation: Claims for the process used to produce Rivastigmine tartrate Form B. This can be a crucial aspect of patent protection, as it can prevent competitors from manufacturing the patented form, even if they don't sell it directly. The scope of these claims is critical for understanding the competitive landscape and potential infringement risks. What is the Commercial Significance of Rivastigmine Tartrate? Rivastigmine, marketed under brand names such as Exelon, is a medication primarily used to treat mild to moderate dementia associated with Alzheimer's disease and Parkinson's disease. It works by increasing the levels of acetylcholine in the brain, a neurotransmitter that plays a role in memory and cognition. The development of a specific crystalline form, like Form B in US 5,674,850, is often driven by the need to improve the drug's performance and manufacturability. Key advantages of a well-defined crystalline form can include: Improved Stability: Certain polymorphic forms are more stable than others, leading to a longer shelf life for the drug product and preventing degradation. Enhanced Bioavailability: The rate and extent to which a drug is absorbed into the bloodstream can be influenced by its crystalline form. A more soluble or more readily dissolvable polymorph can lead to better therapeutic outcomes. Consistent Manufacturing: A defined crystalline form ensures batch-to-batch consistency in the drug substance, which is essential for regulatory approval and reliable drug performance. Reproducible physical properties simplify formulation development and manufacturing processes. Patent Protection: Developing a novel crystalline form can provide an opportunity for extended market exclusivity beyond the initial patent life of the active pharmaceutical ingredient itself. This is a common strategy in the pharmaceutical industry to protect market share. Given the prevalence of neurodegenerative diseases like Alzheimer's, the market for treatments such as rivastigmine is substantial. Consequently, patent protection for advantageous forms of the drug substance holds significant commercial value. What is the Patent Landscape for Rivastigmine? The patent landscape for a drug like rivastigmine is complex, typically involving multiple patents covering different aspects of the molecule and its use. US Patent 5,674,850 is one piece of this larger puzzle. The landscape generally includes: Composition of Matter Patents: These are the most fundamental patents, covering the active pharmaceutical ingredient itself. The original patent for rivastigmine would have been a composition of matter patent. Process Patents: These patents protect specific methods of synthesizing rivastigmine. Formulation Patents: These cover specific ways of delivering the drug, such as particular tablet compositions, capsules, transdermal patches, or liquid formulations. Polymorph Patents: Like US 5,674,850, these patents protect specific crystalline or amorphous forms of the drug substance that exhibit superior properties. Use Patents: These patents cover the use of rivastigmine for treating specific medical conditions or patient populations. The expiry of early composition of matter patents often triggers the entry of generic competition. However, the presence of later-expiring patents, such as those for specific polymorphs or advanced formulations, can extend market exclusivity for the innovator company. Generic manufacturers must carefully navigate this patent landscape to avoid infringement. They may seek to develop their own generic versions using different crystalline forms, synthesis routes, or formulations that do not infringe on existing patents. For US 5,674,850, its primary impact is on generic manufacturers seeking to produce rivastigmine tartrate. If a generic manufacturer's product uses rivastigmine tartrate in the specific crystalline Form B claimed in this patent, it would constitute infringement, potentially leading to legal challenges and injunctions. Companies developing generics would therefore need to ascertain if their rivastigmine tartrate is in Form B or another, non-infringing crystalline form. The effective lifespan of patent protection for a drug can be extended through strategies like obtaining patents on new polymorphs, as seen with US 5,674,850. This particular patent, granted in 1997, would have contributed to extended market protection for rivastigmine beyond the initial expiration of its composition of matter patent. What are the Implications of US 5,674,850 for R&D and Investment? The analysis of US Patent 5,674,850 has direct implications for both research and development (R&D) and investment decisions within the pharmaceutical sector, particularly concerning rivastigmine or similar carbamate-based cholinesterase inhibitors. For R&D: Form Development Strategy: For companies developing new formulations or generic versions of rivastigmine, understanding the claims of this patent is paramount. R&D teams must ensure that any crystalline form of rivastigmine tartrate they develop and intend to commercialize does not fall within the scope of Claim 1 and its dependent claims. This necessitates rigorous polymorph screening and characterization to identify and utilize non-infringing crystalline forms. Intellectual Property Creation: The patent itself serves as a model for R&D efforts aimed at generating novel intellectual property. Identifying and characterizing advantageous polymorphic forms of existing or new drug candidates is a proven strategy for extending market exclusivity and creating valuable IP assets. Companies can explore other potential crystalline forms of rivastigmine or different salts and solvates that may offer similar or improved properties without infringing on existing patents. Lifecycle Management: For the innovator company (Novartis), patents like this are crucial for lifecycle management. They allow for the extension of market exclusivity by protecting improved or novel forms of the drug. R&D efforts would continue to focus on optimizing drug delivery (e.g., transdermal patches) and exploring new therapeutic indications, supported by the IP surrounding the molecule. For Investment: Generic Market Entry Risk: Investors considering companies that plan to launch generic rivastigmine must assess the patent landscape, including patents like US 5,674,850. A successful challenge to the patent or the development of a non-infringing generic can significantly impact the profitability of a generic launch. Conversely, for the innovator, continued protection from such patents supports sustained revenue streams. Valuation of IP Portfolios: For pharmaceutical companies, the strength and breadth of their patent portfolio, including patents on specific crystalline forms, are critical components of their valuation. Investors assess the ability of these patents to protect market share and generate future revenue. The existence and remaining term of patents like US 5,674,850 contribute to the overall IP value of a drug. Competitive Landscape Analysis: Investment decisions are informed by the competitive environment. The presence of patents on specific forms can deter competitors or necessitate significant investment in R&D to circumvent existing IP. Understanding these barriers to entry is vital for assessing market potential and competitive dynamics. Investors look for companies with robust IP strategies that secure market exclusivity and competitive advantage. The existence of US 5,674,850 highlights the importance of detailed chemical and structural analysis in pharmaceutical R&D and due diligence for investment. It demonstrates how specific physical characteristics of an active pharmaceutical ingredient can be the subject of valuable patent protection. Key Takeaways US Patent 5,674,850 protects a specific crystalline form of Rivastigmine tartrate, designated as Form B. This Form B is characterized by distinct X-ray powder diffraction (XRPD) peaks, differential scanning calorimetry (DSC) profiles, and infrared spectroscopy (IR) spectra. The patent claims cover the compound in this crystalline form, its preparation, and pharmaceutical compositions containing it. The development of specific crystalline forms is a strategy to improve drug stability, bioavailability, and manufacturing consistency, and to extend market exclusivity. The patent landscape for rivastigmine includes multiple patents covering composition, process, formulation, and specific crystalline forms. US 5,674,850 impacts generic drug development by requiring competitors to identify and utilize non-infringing crystalline forms of rivastigmine tartrate. For R&D, the patent informs polymorph selection and IP strategy. For investment, it influences risk assessment for generic entry and valuation of IP portfolios. FAQs What is the expiration date of US Patent 5,674,850? The patent was granted on October 7, 1997. As a utility patent in the United States, it typically has a term of 20 years from the filing date, subject to maintenance fees and potential extensions for patent term adjustments or regulatory delays. Assuming a filing date around 1996-1997, the patent would have expired around 2016-2017. Does this patent prevent the use of any form of Rivastigmine? No, this patent specifically protects Rivastigmine tartrate in a particular crystalline form (Form B). It does not prevent the use or sale of Rivastigmine in other crystalline forms, amorphous forms, or as different salts or solvates, provided these are not covered by other patents. How does a generic company avoid infringing this patent? A generic company can avoid infringing US 5,674,850 by demonstrating that its rivastigmine tartrate product is not in the crystalline Form B claimed by the patent. This typically involves characterization using XRPD, DSC, and IR spectroscopy to confirm the presence of a different, non-infringing crystalline form. What are the key differences between crystalline forms of a drug? Crystalline forms of the same drug, known as polymorphs, differ in their atomic arrangement within the crystal lattice. This leads to variations in physical properties such as solubility, dissolution rate, melting point, density, stability, and hygroscopicity. These differences can significantly affect a drug's performance, manufacturability, and bioavailability. Can this patent be challenged? Yes, like any patent, US 5,674,850 could be challenged in court or through post-grant review proceedings. Challenges are typically based on arguments of lack of novelty, obviousness, or insufficient written description and enablement in the patent disclosure. Citations [1] Sandoz AG. (1997). Crystalline form of (S)-3-[1-(Dimethylamino)ethyl]phenyl ethyl(methyl)carbamate tartrate (U.S. Patent No. 5,674,850). Washington, DC: U.S. Patent and Trademark Office. More… ↓ ⤷ Start Trial

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Details for Patent: 5,674,850

Summary for Patent: 5,674,850