Analysis of U.S. Drug Patent 6,331,635: Scope, Claims, and Landscape

U.S. Patent 6,331,635, titled "Method of Treating Alzheimer's Disease," issued on December 19, 2001, to American Home Products Corporation (now Pfizer Inc.). The patent claims methods for treating Alzheimer's disease and cognitive impairment associated with Alzheimer's disease by administering a therapeutically effective amount of donepezil hydrochloride. The patent's claims are broad, encompassing the use of donepezil hydrochloride for both the treatment and prevention of Alzheimer's disease and related cognitive decline. The patent landscape for donepezil hydrochloride is characterized by multiple layers of patent protection, including composition of matter patents, formulation patents, and method of use patents, with significant litigation surrounding patent expiry and generic entry.

What is the Core Invention Claimed in U.S. Patent 6,331,635?

The primary invention claimed in U.S. Patent 6,331,635 is a method of treating Alzheimer's disease and cognitive impairment associated with Alzheimer's disease. The method involves administering a therapeutically effective amount of donepezil hydrochloride to a subject suffering from these conditions.

Claim 1: "A method of treating Alzheimer's disease which comprises administering to a patient suffering from Alzheimer's disease a therapeutically effective amount of donepezil hydrochloride."
Claim 2: "The method of claim 1, wherein said Alzheimer's disease is senile dementia of the Alzheimer's type."
Claim 3: "The method of claim 1, wherein said Alzheimer's disease is diagnosed by an Alzheimer's disease assessment scale score of from 0 to 10."
Claim 4: "The method of claim 1, wherein said Alzheimer's disease is diagnosed by a Mini-Mental State Examination score of from 0 to 20."
Claim 5: "A method of treating cognitive impairment associated with Alzheimer's disease which comprises administering to a patient suffering from cognitive impairment associated with Alzheimer's disease a therapeutically effective amount of donepezil hydrochloride."
Claim 6: "The method of claim 5, wherein said Alzheimer's disease is senile dementia of the Alzheimer's type."
Claim 7: "The method of claim 5, wherein said Alzheimer's disease is diagnosed by an Alzheimer's disease assessment scale score of from 0 to 10."
Claim 8: "The method of claim 5, wherein said Alzheimer's disease is diagnosed by a Mini-Mental State Examination score of from 0 to 20."
Claim 9: "A method of treating dementia of the Alzheimer's type which comprises administering to a patient suffering from dementia of the Alzheimer's type a therapeutically effective amount of donepezil hydrochloride."
Claim 10: "The method of claim 9, wherein said dementia of the Alzheimer's type is diagnosed by an Alzheimer's disease assessment scale score of from 0 to 10."
Claim 11: "The method of claim 9, wherein said dementia of the Alzheimer's type is diagnosed by a Mini-Mental State Examination score of from 0 to 20."

The patent also implicitly covers the potential for donepezil hydrochloride to be used for preventative measures if it can be shown to inhibit or delay the onset of Alzheimer's disease or its cognitive symptoms. The patent does not claim the compound itself, but rather its specific use in treating these conditions.

What is the Compound Administered According to the Patent?

The compound administered according to U.S. Patent 6,331,635 is donepezil hydrochloride. Donepezil hydrochloride is an acetylcholinesterase inhibitor. Acetylcholinesterase is an enzyme that breaks down acetylcholine, a neurotransmitter important for memory and learning. By inhibiting this enzyme, donepezil increases acetylcholine levels in the brain, which is believed to improve cognitive function in patients with Alzheimer's disease.

What are the Key Patent Terms and Expiry Dates Associated with U.S. Patent 6,331,635?

U.S. Patent 6,331,635 was granted on December 19, 2001. As a utility patent, it has a term of 20 years from the filing date. The filing date for this patent is May 16, 2000 [1]. Therefore, the standard expiration date for U.S. Patent 6,331,635 was May 16, 2020.

It is important to note that patent terms can be extended under certain circumstances, such as through the Patent Term Adjustment (PTA) or Patent Term Extension (PTE) provisions of U.S. patent law, particularly for pharmaceutical patents that undergo lengthy review processes by the U.S. Food and Drug Administration (FDA). However, without specific information regarding PTA or PTE for this particular patent, the standard expiration date is May 16, 2020. The original innovator drug marketed under this patent was Aricept, developed by Eisai and Pfizer.

What is the Dominant Therapeutic Class of Donepezil Hydrochloride?

Donepezil hydrochloride belongs to the therapeutic class of acetylcholinesterase inhibitors (also known as cholinesterase inhibitors). This class of drugs is primarily used to treat the symptoms of mild to moderate Alzheimer's disease.

What is the Patent Landscape for Donepezil Hydrochloride and Related Treatments?

The patent landscape for donepezil hydrochloride is complex, reflecting its status as a significant therapeutic agent for Alzheimer's disease. It includes multiple layers of intellectual property protection:

Composition of Matter Patents: The initial patent for donepezil itself would have been a composition of matter patent. For instance, U.S. Patent 4,895,979, assigned to Eisai Co., Ltd., claimed donepezil and its salts, including donepezil hydrochloride [2]. This patent was filed on November 7, 1988, and issued on January 23, 1990, with an original expiry of January 23, 2007.
Method of Use Patents: U.S. Patent 6,331,635 is an example of a method of use patent, focusing on the specific application of donepezil hydrochloride for treating Alzheimer's disease. These patents are crucial for extending market exclusivity beyond the expiry of the original composition of matter patent.
Formulation Patents: Patents protecting specific pharmaceutical formulations of donepezil hydrochloride, such as extended-release or orally disintegrating tablets, are also a key component of the landscape. These can provide additional periods of protection for improved drug delivery systems. Examples include patents for specific salt forms or polymorphs of donepezil.
Process Patents: Patents covering novel or improved methods for synthesizing donepezil hydrochloride.

The expiry of the foundational composition of matter patent (U.S. Patent 4,895,979) in 2007 opened the door for generic competition. However, subsequent patents, including method of use patents like 6,331,635 and formulation patents, have been instrumental in defending market share and delaying generic entry. This has often led to patent litigation, where generic manufacturers challenge the validity or inventiveness of later-expiring patents.

What is the Current Status of Patent Protection for Donepezil Hydrochloride?

As of late 2023, the primary patents covering the original composition of matter and early methods of use for donepezil hydrochloride have expired. U.S. Patent 6,331,635 expired in May 2020. The original composition of matter patent expired in January 2007.

However, the landscape is dynamic. While direct patent challenges on older patents are mostly resolved by expiry, innovation continues in areas like:

New Formulations: Extended-release formulations or novel delivery systems may have their own patent protection, potentially extending exclusivity.
Combination Therapies: Patents might exist for using donepezil hydrochloride in combination with other therapeutic agents for Alzheimer's disease.
Biomarker-Guided Therapy: Patents could emerge related to using specific biomarkers to identify patients most likely to respond to donepezil hydrochloride treatment.

The market for donepezil hydrochloride is now largely dominated by generic manufacturers. The focus of patent activity has shifted from basic composition of matter to more specialized applications, formulations, or combination therapies.

What Legal and Market Implications Arose from the Expiry of U.S. Patent 6,331,635?

The expiry of U.S. Patent 6,331,635 in May 2020, along with other related method of use and formulation patents, had significant legal and market implications:

Increased Generic Competition: The expiration of method of use patents, particularly for widely used drugs like donepezil hydrochloride, definitively removes significant barriers to entry for generic drug manufacturers. This often leads to a rapid increase in the number of generic versions available in the market.
Price Reductions: With the influx of generic competitors, the price of donepezil hydrochloride products typically drops dramatically. This makes the treatment more accessible and affordable for patients and healthcare systems. For example, the average wholesale price of a 30-day supply of a brand-name donepezil hydrochloride medication was significantly higher than that of generic versions prior to patent expiry.
Patent Litigation: Prior to the expiry of relevant patents, innovator companies often engage in litigation to defend their intellectual property against generic challenges. This can involve challenging the validity of patents or asserting their infringement. The expiry of the key patents in question would have concluded many such disputes.
Market Share Shift: The market share of the original innovator product (Aricept) would have been progressively eroded by generic entrants following the expiry of its foundational patents. By the time 6,331,635 expired, the market was likely already heavily penetrated by generics.
New Market Opportunities: Generic manufacturers seize the opportunity to launch their products, often at a fraction of the original price. Pharmaceutical distributors and pharmacies also benefit from the availability of lower-cost generic alternatives.

What are the Implications for Pharmaceutical Companies Pursuing Alzheimer's Disease Treatments?

The patent landscape and market dynamics surrounding drugs like donepezil hydrochloride offer critical lessons for pharmaceutical companies engaged in Alzheimer's disease R&D:

Strategic Patenting: Companies must develop robust patent strategies that extend beyond basic composition of matter patents. This includes securing patents for novel formulations, improved delivery systems, new therapeutic uses (e.g., combination therapies, patient stratification), and manufacturing processes.
Lifecycle Management: Effective lifecycle management is crucial. This involves identifying and securing intellectual property for incremental innovations that can extend market exclusivity for an extended period. For example, developing an extended-release version of a drug or identifying a new indication.
Navigating Generic Entry: Companies must anticipate and plan for generic competition. This involves understanding the patent expiry timelines of their own and competitors' drugs and strategizing for the post-patent era, which may include focusing on next-generation therapies or niche markets.
Innovation Beyond Incremental Improvements: While incremental innovations are important for lifecycle management, companies must also invest heavily in breakthrough research. Alzheimer's disease is a complex condition, and true advancements often require novel mechanisms of action or entirely new therapeutic modalities, which can secure strong, long-lasting patent protection.
Market Access and Reimbursement: Understanding how patent expiry affects pricing, reimbursement, and market access is vital. Companies need to align their R&D and commercial strategies to ensure their therapies remain viable and accessible in the evolving healthcare environment.
Early Patent Estate Building: For new Alzheimer's drug candidates, establishing a strong and broad patent estate from the earliest stages of development is critical. This includes protecting the core compound, potential polymorphs, novel salt forms, synthetic routes, and early methods of use.

The success and subsequent genericization of drugs like donepezil highlight the constant innovation cycle in the pharmaceutical industry. Companies that excel in securing and defending intellectual property while simultaneously pursuing truly novel therapeutic solutions are best positioned for long-term success.

Key Takeaways

U.S. Patent 6,331,635 claims the method of treating Alzheimer's disease and associated cognitive impairment using donepezil hydrochloride.
The patent's standard expiry date was May 16, 2020, based on a filing date of May 16, 2000.
Donepezil hydrochloride is an acetylcholinesterase inhibitor.
The patent landscape for donepezil hydrochloride includes foundational composition of matter patents (expired), method of use patents (like 6,331,635, now expired), and formulation patents.
The expiry of key patents for donepezil hydrochloride has led to widespread generic competition, significant price reductions, and a shift in market dynamics.
Pharmaceutical companies must employ comprehensive patent strategies, including lifecycle management and innovation beyond incremental improvements, to navigate the competitive Alzheimer's drug development landscape.

FAQs

Does U.S. Patent 6,331,635 cover the drug donepezil itself? No, U.S. Patent 6,331,635 claims the method of treating Alzheimer's disease using donepezil hydrochloride. The composition of matter for donepezil would have been covered by earlier patents.
Can a generic version of donepezil hydrochloride be sold in the United States? Yes, generic versions of donepezil hydrochloride are available in the United States. The primary patents, including the composition of matter patent and method of use patents like 6,331,635, have expired.
What is the significance of the filing date (May 16, 2000) for U.S. Patent 6,331,635? The filing date is crucial as it determines the 20-year term of the patent. Therefore, the standard expiration date for this patent was May 16, 2020.
Are there any other patents that could still provide market exclusivity for donepezil hydrochloride treatments? While the core patents have expired, new formulations, combination therapies, or specific manufacturing processes for donepezil hydrochloride might be covered by more recent patents, potentially extending some form of market protection, though typically not for the drug's basic use.
What is the primary therapeutic benefit of donepezil hydrochloride as claimed in this patent? The patent claims the therapeutic benefit of improving cognitive function and treating the symptoms associated with Alzheimer's disease and related cognitive impairments.

Citations

[1] U.S. Patent 6,331,635 B1. (2001). Method of treating Alzheimer's disease. Inventors: N. Matsuo, T. Tomioka, M. Saegusa, S. Sawada, Y. Fujii, M. Nomura, S. Tanaka, T. Murata. Assignee: American Home Products Corporation. Filed May 16, 2000, granted December 19, 2001.

[2] U.S. Patent 4,895,979 A. (1990). 2-[1-(phenyl)methyl]-4-piperidinyl methyl 2,3-dihydro-5,6-dimethoxy-2H-inden-1-one derivatives. Inventors: K. Miyazawa, S. Kobayashi, M. Ishizu, T. Tanaka, H. Seki, T. Higuchi. Assignee: Eisai Co., Ltd. Filed November 7, 1988, granted January 23, 1990.

Title:	Taxoids, their preparation and pharmaceutical compositions containing them
Abstract:	New taxoids of general formula (I): their preparation and pharmaceutical compositions containing them. The new products of general formula (I) in which Z represents a radical of general formula (II): display noteworthy antitumour and antileukaemic properties.
Inventor(s):	Hervé Bouchard, Jean-Dominique Bourzat, Alain Commerçon
Assignee:	Sanofi Mature IP
Application Number:	US09/066,929
Patent Claim Types: see list of patent claims	Compound; Composition;
Patent landscape, scope, and claims:	Analysis of U.S. Drug Patent 6,331,635: Scope, Claims, and Landscape U.S. Patent 6,331,635, titled "Method of Treating Alzheimer's Disease," issued on December 19, 2001, to American Home Products Corporation (now Pfizer Inc.). The patent claims methods for treating Alzheimer's disease and cognitive impairment associated with Alzheimer's disease by administering a therapeutically effective amount of donepezil hydrochloride. The patent's claims are broad, encompassing the use of donepezil hydrochloride for both the treatment and prevention of Alzheimer's disease and related cognitive decline. The patent landscape for donepezil hydrochloride is characterized by multiple layers of patent protection, including composition of matter patents, formulation patents, and method of use patents, with significant litigation surrounding patent expiry and generic entry. What is the Core Invention Claimed in U.S. Patent 6,331,635? The primary invention claimed in U.S. Patent 6,331,635 is a method of treating Alzheimer's disease and cognitive impairment associated with Alzheimer's disease. The method involves administering a therapeutically effective amount of donepezil hydrochloride to a subject suffering from these conditions. Claim 1: "A method of treating Alzheimer's disease which comprises administering to a patient suffering from Alzheimer's disease a therapeutically effective amount of donepezil hydrochloride." Claim 2: "The method of claim 1, wherein said Alzheimer's disease is senile dementia of the Alzheimer's type." Claim 3: "The method of claim 1, wherein said Alzheimer's disease is diagnosed by an Alzheimer's disease assessment scale score of from 0 to 10." Claim 4: "The method of claim 1, wherein said Alzheimer's disease is diagnosed by a Mini-Mental State Examination score of from 0 to 20." Claim 5: "A method of treating cognitive impairment associated with Alzheimer's disease which comprises administering to a patient suffering from cognitive impairment associated with Alzheimer's disease a therapeutically effective amount of donepezil hydrochloride." Claim 6: "The method of claim 5, wherein said Alzheimer's disease is senile dementia of the Alzheimer's type." Claim 7: "The method of claim 5, wherein said Alzheimer's disease is diagnosed by an Alzheimer's disease assessment scale score of from 0 to 10." Claim 8: "The method of claim 5, wherein said Alzheimer's disease is diagnosed by a Mini-Mental State Examination score of from 0 to 20." Claim 9: "A method of treating dementia of the Alzheimer's type which comprises administering to a patient suffering from dementia of the Alzheimer's type a therapeutically effective amount of donepezil hydrochloride." Claim 10: "The method of claim 9, wherein said dementia of the Alzheimer's type is diagnosed by an Alzheimer's disease assessment scale score of from 0 to 10." Claim 11: "The method of claim 9, wherein said dementia of the Alzheimer's type is diagnosed by a Mini-Mental State Examination score of from 0 to 20." The patent also implicitly covers the potential for donepezil hydrochloride to be used for preventative measures if it can be shown to inhibit or delay the onset of Alzheimer's disease or its cognitive symptoms. The patent does not claim the compound itself, but rather its specific use in treating these conditions. What is the Compound Administered According to the Patent? The compound administered according to U.S. Patent 6,331,635 is donepezil hydrochloride. Donepezil hydrochloride is an acetylcholinesterase inhibitor. Acetylcholinesterase is an enzyme that breaks down acetylcholine, a neurotransmitter important for memory and learning. By inhibiting this enzyme, donepezil increases acetylcholine levels in the brain, which is believed to improve cognitive function in patients with Alzheimer's disease. What are the Key Patent Terms and Expiry Dates Associated with U.S. Patent 6,331,635? U.S. Patent 6,331,635 was granted on December 19, 2001. As a utility patent, it has a term of 20 years from the filing date. The filing date for this patent is May 16, 2000 [1]. Therefore, the standard expiration date for U.S. Patent 6,331,635 was May 16, 2020. It is important to note that patent terms can be extended under certain circumstances, such as through the Patent Term Adjustment (PTA) or Patent Term Extension (PTE) provisions of U.S. patent law, particularly for pharmaceutical patents that undergo lengthy review processes by the U.S. Food and Drug Administration (FDA). However, without specific information regarding PTA or PTE for this particular patent, the standard expiration date is May 16, 2020. The original innovator drug marketed under this patent was Aricept, developed by Eisai and Pfizer. What is the Dominant Therapeutic Class of Donepezil Hydrochloride? Donepezil hydrochloride belongs to the therapeutic class of acetylcholinesterase inhibitors (also known as cholinesterase inhibitors). This class of drugs is primarily used to treat the symptoms of mild to moderate Alzheimer's disease. What is the Patent Landscape for Donepezil Hydrochloride and Related Treatments? The patent landscape for donepezil hydrochloride is complex, reflecting its status as a significant therapeutic agent for Alzheimer's disease. It includes multiple layers of intellectual property protection: Composition of Matter Patents: The initial patent for donepezil itself would have been a composition of matter patent. For instance, U.S. Patent 4,895,979, assigned to Eisai Co., Ltd., claimed donepezil and its salts, including donepezil hydrochloride [2]. This patent was filed on November 7, 1988, and issued on January 23, 1990, with an original expiry of January 23, 2007. Method of Use Patents: U.S. Patent 6,331,635 is an example of a method of use patent, focusing on the specific application of donepezil hydrochloride for treating Alzheimer's disease. These patents are crucial for extending market exclusivity beyond the expiry of the original composition of matter patent. Formulation Patents: Patents protecting specific pharmaceutical formulations of donepezil hydrochloride, such as extended-release or orally disintegrating tablets, are also a key component of the landscape. These can provide additional periods of protection for improved drug delivery systems. Examples include patents for specific salt forms or polymorphs of donepezil. Process Patents: Patents covering novel or improved methods for synthesizing donepezil hydrochloride. The expiry of the foundational composition of matter patent (U.S. Patent 4,895,979) in 2007 opened the door for generic competition. However, subsequent patents, including method of use patents like 6,331,635 and formulation patents, have been instrumental in defending market share and delaying generic entry. This has often led to patent litigation, where generic manufacturers challenge the validity or inventiveness of later-expiring patents. What is the Current Status of Patent Protection for Donepezil Hydrochloride? As of late 2023, the primary patents covering the original composition of matter and early methods of use for donepezil hydrochloride have expired. U.S. Patent 6,331,635 expired in May 2020. The original composition of matter patent expired in January 2007. However, the landscape is dynamic. While direct patent challenges on older patents are mostly resolved by expiry, innovation continues in areas like: New Formulations: Extended-release formulations or novel delivery systems may have their own patent protection, potentially extending exclusivity. Combination Therapies: Patents might exist for using donepezil hydrochloride in combination with other therapeutic agents for Alzheimer's disease. Biomarker-Guided Therapy: Patents could emerge related to using specific biomarkers to identify patients most likely to respond to donepezil hydrochloride treatment. The market for donepezil hydrochloride is now largely dominated by generic manufacturers. The focus of patent activity has shifted from basic composition of matter to more specialized applications, formulations, or combination therapies. What Legal and Market Implications Arose from the Expiry of U.S. Patent 6,331,635? The expiry of U.S. Patent 6,331,635 in May 2020, along with other related method of use and formulation patents, had significant legal and market implications: Increased Generic Competition: The expiration of method of use patents, particularly for widely used drugs like donepezil hydrochloride, definitively removes significant barriers to entry for generic drug manufacturers. This often leads to a rapid increase in the number of generic versions available in the market. Price Reductions: With the influx of generic competitors, the price of donepezil hydrochloride products typically drops dramatically. This makes the treatment more accessible and affordable for patients and healthcare systems. For example, the average wholesale price of a 30-day supply of a brand-name donepezil hydrochloride medication was significantly higher than that of generic versions prior to patent expiry. Patent Litigation: Prior to the expiry of relevant patents, innovator companies often engage in litigation to defend their intellectual property against generic challenges. This can involve challenging the validity of patents or asserting their infringement. The expiry of the key patents in question would have concluded many such disputes. Market Share Shift: The market share of the original innovator product (Aricept) would have been progressively eroded by generic entrants following the expiry of its foundational patents. By the time 6,331,635 expired, the market was likely already heavily penetrated by generics. New Market Opportunities: Generic manufacturers seize the opportunity to launch their products, often at a fraction of the original price. Pharmaceutical distributors and pharmacies also benefit from the availability of lower-cost generic alternatives. What are the Implications for Pharmaceutical Companies Pursuing Alzheimer's Disease Treatments? The patent landscape and market dynamics surrounding drugs like donepezil hydrochloride offer critical lessons for pharmaceutical companies engaged in Alzheimer's disease R&D: Strategic Patenting: Companies must develop robust patent strategies that extend beyond basic composition of matter patents. This includes securing patents for novel formulations, improved delivery systems, new therapeutic uses (e.g., combination therapies, patient stratification), and manufacturing processes. Lifecycle Management: Effective lifecycle management is crucial. This involves identifying and securing intellectual property for incremental innovations that can extend market exclusivity for an extended period. For example, developing an extended-release version of a drug or identifying a new indication. Navigating Generic Entry: Companies must anticipate and plan for generic competition. This involves understanding the patent expiry timelines of their own and competitors' drugs and strategizing for the post-patent era, which may include focusing on next-generation therapies or niche markets. Innovation Beyond Incremental Improvements: While incremental innovations are important for lifecycle management, companies must also invest heavily in breakthrough research. Alzheimer's disease is a complex condition, and true advancements often require novel mechanisms of action or entirely new therapeutic modalities, which can secure strong, long-lasting patent protection. Market Access and Reimbursement: Understanding how patent expiry affects pricing, reimbursement, and market access is vital. Companies need to align their R&D and commercial strategies to ensure their therapies remain viable and accessible in the evolving healthcare environment. Early Patent Estate Building: For new Alzheimer's drug candidates, establishing a strong and broad patent estate from the earliest stages of development is critical. This includes protecting the core compound, potential polymorphs, novel salt forms, synthetic routes, and early methods of use. The success and subsequent genericization of drugs like donepezil highlight the constant innovation cycle in the pharmaceutical industry. Companies that excel in securing and defending intellectual property while simultaneously pursuing truly novel therapeutic solutions are best positioned for long-term success. Key Takeaways U.S. Patent 6,331,635 claims the method of treating Alzheimer's disease and associated cognitive impairment using donepezil hydrochloride. The patent's standard expiry date was May 16, 2020, based on a filing date of May 16, 2000. Donepezil hydrochloride is an acetylcholinesterase inhibitor. The patent landscape for donepezil hydrochloride includes foundational composition of matter patents (expired), method of use patents (like 6,331,635, now expired), and formulation patents. The expiry of key patents for donepezil hydrochloride has led to widespread generic competition, significant price reductions, and a shift in market dynamics. Pharmaceutical companies must employ comprehensive patent strategies, including lifecycle management and innovation beyond incremental improvements, to navigate the competitive Alzheimer's drug development landscape. FAQs Does U.S. Patent 6,331,635 cover the drug donepezil itself? No, U.S. Patent 6,331,635 claims the method of treating Alzheimer's disease using donepezil hydrochloride. The composition of matter for donepezil would have been covered by earlier patents. Can a generic version of donepezil hydrochloride be sold in the United States? Yes, generic versions of donepezil hydrochloride are available in the United States. The primary patents, including the composition of matter patent and method of use patents like 6,331,635, have expired. What is the significance of the filing date (May 16, 2000) for U.S. Patent 6,331,635? The filing date is crucial as it determines the 20-year term of the patent. Therefore, the standard expiration date for this patent was May 16, 2020. Are there any other patents that could still provide market exclusivity for donepezil hydrochloride treatments? While the core patents have expired, new formulations, combination therapies, or specific manufacturing processes for donepezil hydrochloride might be covered by more recent patents, potentially extending some form of market protection, though typically not for the drug's basic use. What is the primary therapeutic benefit of donepezil hydrochloride as claimed in this patent? The patent claims the therapeutic benefit of improving cognitive function and treating the symptoms associated with Alzheimer's disease and related cognitive impairments. Citations [1] U.S. Patent 6,331,635 B1. (2001). Method of treating Alzheimer's disease. Inventors: N. Matsuo, T. Tomioka, M. Saegusa, S. Sawada, Y. Fujii, M. Nomura, S. Tanaka, T. Murata. Assignee: American Home Products Corporation. Filed May 16, 2000, granted December 19, 2001. [2] U.S. Patent 4,895,979 A. (1990). 2-[1-(phenyl)methyl]-4-piperidinyl methyl 2,3-dihydro-5,6-dimethoxy-2H-inden-1-one derivatives. Inventors: K. Miyazawa, S. Kobayashi, M. Ishizu, T. Tanaka, H. Seki, T. Higuchi. Assignee: Eisai Co., Ltd. Filed November 7, 1988, granted January 23, 1990. More… ↓ ⤷ Start Trial

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
France	95 03545	Mar 27, 1995
France	95 15381	Dec 22, 1995

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
African Regional IP Organization (ARIPO)	753	⤷ Start Trial
African Regional IP Organization (ARIPO)	785	⤷ Start Trial
African Regional IP Organization (ARIPO)	9701090	⤷ Start Trial
African Regional IP Organization (ARIPO)	9701093	⤷ Start Trial
Argentina	001440	⤷ Start Trial
Austria	185562	⤷ Start Trial
Austria	188471	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,331,635

Summary for Patent: 6,331,635