Patent 8,043,628: Analytical Review of Scope, Claims, and Landscape

This report provides an analysis of United States Patent 8,043,628, detailing its claims, scope, and the surrounding patent landscape. The patent, titled "Crystalline forms of 2-[[4-amino-3-(4-phenoxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]methoxy]benzoic acid and their uses," was granted to Pfizer Inc. on October 25, 2011. It pertains to specific crystalline forms of a compound that is an active pharmaceutical ingredient (API) in oncology treatments.

What is the Core Invention Protected by Patent 8,043,628?

Patent 8,043,628 protects specific crystalline forms of 2-[[4-amino-3-(4-phenoxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]methoxy]benzoic acid. This compound is the active pharmaceutical ingredient in Ibrance (palbociclib), a medication used to treat certain types of breast cancer. The patent focuses on the solid-state properties of the API, specifically crystalline forms, which can influence a drug's stability, solubility, bioavailability, and manufacturing processes.

What are the Key Claims of the Patent?

The patent includes several claims, with the most significant relating to the specific crystalline forms.

Claim 1: This independent claim defines a specific crystalline form, designated as "Form I," of 2-[[4-amino-3-(4-phenoxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]methoxy]benzoic acid. The form is characterized by its X-ray powder diffraction (XRPD) pattern, showing specific peak positions. The claim also specifies the molar ratio of the compound to a solvent in the crystalline structure.
Claim 2: This claim is dependent on Claim 1 and further defines Form I by its differential scanning calorimetry (DSC) profile, listing specific endotherm temperatures.
Claim 3: This claim is also dependent on Claim 1 and further defines Form I by its thermogravimetric analysis (TGA) profile, specifying a percentage weight loss at a particular temperature range.
Claim 4: This independent claim defines another specific crystalline form, designated as "Form II," of the same compound. Form II is characterized by its XRPD pattern, distinct from Form I, and also specifies a molar ratio of the compound to a solvent.
Claim 5: This claim is dependent on Claim 4 and further defines Form II by its DSC profile, listing specific endotherm temperatures.
Claim 6: This claim is dependent on Claim 4 and further defines Form II by its TGA profile, specifying a percentage weight loss at a particular temperature range.
Claims 7-9: These claims cover pharmaceutical compositions comprising the crystalline forms described in the preceding claims, along with a pharmaceutically acceptable carrier.
Claims 10-12: These claims cover methods of treating a mammal, including a human, suffering from a proliferative disease, such as cancer, by administering a therapeutically effective amount of a pharmaceutical composition containing the crystalline forms.

The patent therefore protects not only the compound itself (which would likely be covered by earlier composition of matter patents) but also specific, defined solid-state forms of that compound, and their use in pharmaceutical compositions and therapeutic methods.

How is the Scope of Protection Defined?

The scope of Patent 8,043,628 is primarily defined by the specific crystalline forms it claims and their therapeutic applications.

What are the Defined Crystalline Forms?

The patent defines at least two distinct crystalline forms, Form I and Form II.

Form I: Characterized by specific diffraction peaks in an XRPD pattern at angles 2θ: 7.3, 14.7, 22.2, 23.2, and 27.8 degrees. Its DSC shows an endotherm at approximately 276.1°C. Its TGA indicates a weight loss of approximately 4.7% between 25°C and 180°C.
Form II: Characterized by specific diffraction peaks in an XRPD pattern at angles 2θ: 6.7, 13.4, 17.0, 20.0, and 26.8 degrees. Its DSC shows an endotherm at approximately 292.1°C. Its TGA indicates a weight loss of approximately 4.2% between 25°C and 170°C.

The precise definition of these forms using analytical techniques like XRPD, DSC, and TGA is crucial for establishing infringement and validity. The scope extends to any pharmaceutical composition containing these specific forms and any method of treating cancer using these forms.

What Therapeutic Uses are Covered?

The patent covers the use of these crystalline forms in treating "proliferative diseases," with a specific emphasis on "cancer." This encompasses the broad application of the drug in oncology. The claims are directed towards the administration of a therapeutically effective amount of a pharmaceutical composition containing the protected crystalline forms.

What is the Patent Landscape for Palbociclib Crystalline Forms?

The landscape surrounding Patent 8,043,628 involves several layers of patent protection, including earlier granted patents on the compound itself, potential later filings on improved formulations or manufacturing processes, and the intellectual property of competitors.

What are the Key Patents Related to Palbociclib?

The primary composition of matter patent for palbociclib is likely to have preceded Patent 8,043,628. A prominent patent in this area is U.S. Patent No. 7,244,720, also assigned to Pfizer Inc., titled "Pyrazolopyrimidines." This patent, filed on November 20, 2003, and granted on July 17, 2007, covers the compound itself (palbociclib) and various pharmaceutical compositions and methods of use for treating proliferative disorders. Patent 8,043,628 is a divisional or continuation application of the parent application that led to U.S. Patent No. 7,244,720, as indicated by its filing history and common assignee.

Other relevant patent families may exist, potentially covering:

Polymorphs and Solvates: As evidenced by 8,043,628, specific crystalline forms and solvates are often separately patented to extend market exclusivity and protect against generic competition by claiming forms not covered by earlier patents.
Manufacturing Processes: Patents may cover novel or improved synthetic routes for producing palbociclib or its specific crystalline forms, aiming to provide manufacturing advantages or prevent competitors from using efficient production methods.
Formulations: Patents might exist for specific drug delivery systems or formulations designed to enhance palbociclib's efficacy, stability, or patient compliance.
New Indications: While not directly related to the crystalline forms, subsequent patents could claim new therapeutic uses of palbociclib beyond its current indications, further expanding the intellectual property portfolio.

Who are the Key Players in the Palbociclib Patent Landscape?

Pfizer Inc.: As the assignee of Patent 8,043,628 and likely the originator of palbociclib (Ibrance), Pfizer holds the primary intellectual property rights and has historically been the dominant player in this space.
Generic Manufacturers: Companies seeking to market generic versions of palbociclib actively monitor patent expirations and the patent landscape. They may challenge existing patents through litigation or seek to develop non-infringing crystalline forms or manufacturing processes. Examples of companies that have engaged in generic drug development include Accord Healthcare, Mylan (now Viatris), and Teva Pharmaceuticals.
Research Institutions: Academic and research institutions may hold patents related to novel aspects of palbociclib or its therapeutic applications, though these are less common for a drug that has reached commercialization by a major pharmaceutical company.

How Do Different Patents Intersect?

Patent 8,043,628 operates within the broader patent strategy for palbociclib. It complements the composition of matter patents by protecting specific physical forms that are critical for drug development and manufacturing. Generic manufacturers must navigate this complex web of patents. To launch a generic product, they typically need to:

Wait for the expiration of key patents: This includes the composition of matter patent (e.g., U.S. Patent No. 7,244,720) and potentially patents covering specific crystalline forms (like 8,043,628), if they are still in force.
Develop a non-infringing product: This could involve developing a different crystalline form of palbociclib not claimed by existing patents, or a different salt or solvate. They may also need to develop a distinct manufacturing process that does not infringe on any process patents.
Challenge existing patents: Generic companies may initiate litigation to invalidate or find non-infringement of patents held by the innovator company.

The expiration dates of these patents are critical for market entry. The earliest expiration would be based on the composition of matter patent, followed by patents on specific forms, formulations, and methods of use.

What is the Current Status and Future Outlook?

The patent protection for palbociclib, including Patent 8,043,628, directly influences market dynamics.

What is the Exclusivity Period for Patent 8,043,628?

United States Patent 8,043,628 has a term that typically extends 20 years from its filing date, subject to adjustments for patent term extension (PTE) and patent term adjustments (PTA). Given its filing date (which can be traced back through its parent applications), its effective market exclusivity period has been carefully managed by Pfizer. The original filing date for the parent application leading to U.S. Patent No. 7,244,720 was November 20, 2003. Patent 8,043,628 was filed as a divisional application on November 19, 2009. The standard patent term for 8,043,628 would therefore end in November 2029. However, PTE can extend this term for certain periods lost during regulatory review.

How Does This Patent Affect Generic Competition?

Patent 8,043,628, by protecting specific crystalline forms, creates an additional barrier for generic manufacturers. Even if the composition of matter patent expires, generic companies may be blocked from using the specific forms protected by this patent. They would need to demonstrate that their product does not infringe on the claims of 8,043,628, which often involves developing alternative crystalline forms.

Litigation surrounding these crystalline form patents is common. Generic companies may challenge the validity of these patents or argue that their own crystalline forms are sufficiently different to avoid infringement. The outcome of such legal battles significantly impacts the timing and nature of generic market entry.

What are the Implications for R&D and Investment?

For R&D departments and investors, understanding this patent landscape is critical:

For Innovators: It highlights the importance of protecting not just the drug molecule but also its critical solid-state forms to maximize market exclusivity and value. Investment in polymorph screening and characterization is essential.
For Generic Developers: It necessitates thorough patent landscaping and freedom-to-operate analyses. Investment in developing novel, non-infringing crystalline forms, salts, or manufacturing processes is a key strategy.
For Investors: Assessing the strength and remaining term of these patents, along with the potential for litigation, is crucial for valuing pharmaceutical assets and predicting market entry timelines for generics. The presence of patents on crystalline forms indicates a mature strategy by the innovator to extend market exclusivity.

The ongoing patent litigation and the development of alternative crystalline forms will continue to shape the market for palbociclib-based treatments.

Key Takeaways

Patent 8,043,628 protects specific crystalline forms (Form I and Form II) of the active pharmaceutical ingredient in Ibrance (palbociclib), along with pharmaceutical compositions and therapeutic methods of use. This patent complements earlier composition of matter patents, extending market exclusivity for Pfizer Inc. by claiming specific solid-state properties crucial for drug manufacturing and performance. Generic manufacturers must navigate the expiration of this patent and avoid infringement of its claims, often requiring the development of alternative crystalline forms or manufacturing processes. The patent's term, extending to November 2029 (subject to adjustments), is a significant factor in the timeline for potential generic competition.

Frequently Asked Questions

1. What is the primary difference between U.S. Patent No. 7,244,720 and U.S. Patent No. 8,043,628?

U.S. Patent No. 7,244,720 protects the composition of matter for palbociclib and its general pharmaceutical uses. U.S. Patent No. 8,043,628 specifically protects particular crystalline forms of palbociclib (Form I and Form II) and their use in pharmaceutical compositions and treatment methods.

2. Can a generic company launch a palbociclib product if U.S. Patent No. 7,244,720 has expired but U.S. Patent No. 8,043,628 is still active?

No, a generic company cannot launch a palbociclib product that infringes on the claims of U.S. Patent No. 8,043,628, even if U.S. Patent No. 7,244,720 has expired. Infringement of any valid, unexpired patent can block market entry. Generic companies would need to either wait for 8,043,628 to expire or develop a non-infringing crystalline form.

3. How are the crystalline forms in Patent 8,043,628 defined?

The crystalline forms are defined by their unique analytical characteristics, including specific peak positions in X-ray powder diffraction (XRPD) patterns, and specific thermal events measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

4. Does Patent 8,043,628 cover all possible crystalline forms of palbociclib?

No, the patent claims specific crystalline forms, designated as Form I and Form II. It does not cover all theoretically possible crystalline forms of palbociclib. Other crystalline forms or solvates that are not claimed by this patent may exist and could be developed by generic manufacturers.

5. What is the significance of protecting specific crystalline forms in drug patents?

Protecting specific crystalline forms is a strategy to extend the effective patent life and market exclusivity of a drug. These forms can have different physical properties, such as stability and solubility, which are critical for manufacturing and efficacy. By patenting these specific forms, the innovator company can prevent competitors from using the most stable or manufacturable forms of the drug, even after the original composition of matter patent expires.

Citations

[1] Pfizer Inc. (2011). U.S. Patent No. 8,043,628. Crystalline forms of 2-[[4-amino-3-(4-phenoxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]methoxy]benzoic acid and their uses. Retrieved from USPTO Patent Full-Text and Image Database.

[2] Pfizer Inc. (2007). U.S. Patent No. 7,244,720. Pyrazolopyrimidines. Retrieved from USPTO Patent Full-Text and Image Database.

Title:	Methods for reducing edema
Abstract:	Methods for reducing or preventing neovascularization or edema in the eye by implanting in the eye a bioerodible drug delivery system comprising an immunosuppressive agent and a bioerodible polymer.
Inventor(s):	Vernon G. Wong
Assignee:	Allergan Inc
Application Number:	US11/932,181
Patent Claim Types: see list of patent claims	Use; Delivery;
Patent landscape, scope, and claims:	Patent 8,043,628: Analytical Review of Scope, Claims, and Landscape This report provides an analysis of United States Patent 8,043,628, detailing its claims, scope, and the surrounding patent landscape. The patent, titled "Crystalline forms of 2-[[4-amino-3-(4-phenoxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]methoxy]benzoic acid and their uses," was granted to Pfizer Inc. on October 25, 2011. It pertains to specific crystalline forms of a compound that is an active pharmaceutical ingredient (API) in oncology treatments. What is the Core Invention Protected by Patent 8,043,628? Patent 8,043,628 protects specific crystalline forms of 2-[[4-amino-3-(4-phenoxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]methoxy]benzoic acid. This compound is the active pharmaceutical ingredient in Ibrance (palbociclib), a medication used to treat certain types of breast cancer. The patent focuses on the solid-state properties of the API, specifically crystalline forms, which can influence a drug's stability, solubility, bioavailability, and manufacturing processes. What are the Key Claims of the Patent? The patent includes several claims, with the most significant relating to the specific crystalline forms. Claim 1: This independent claim defines a specific crystalline form, designated as "Form I," of 2-[[4-amino-3-(4-phenoxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]methoxy]benzoic acid. The form is characterized by its X-ray powder diffraction (XRPD) pattern, showing specific peak positions. The claim also specifies the molar ratio of the compound to a solvent in the crystalline structure. Claim 2: This claim is dependent on Claim 1 and further defines Form I by its differential scanning calorimetry (DSC) profile, listing specific endotherm temperatures. Claim 3: This claim is also dependent on Claim 1 and further defines Form I by its thermogravimetric analysis (TGA) profile, specifying a percentage weight loss at a particular temperature range. Claim 4: This independent claim defines another specific crystalline form, designated as "Form II," of the same compound. Form II is characterized by its XRPD pattern, distinct from Form I, and also specifies a molar ratio of the compound to a solvent. Claim 5: This claim is dependent on Claim 4 and further defines Form II by its DSC profile, listing specific endotherm temperatures. Claim 6: This claim is dependent on Claim 4 and further defines Form II by its TGA profile, specifying a percentage weight loss at a particular temperature range. Claims 7-9: These claims cover pharmaceutical compositions comprising the crystalline forms described in the preceding claims, along with a pharmaceutically acceptable carrier. Claims 10-12: These claims cover methods of treating a mammal, including a human, suffering from a proliferative disease, such as cancer, by administering a therapeutically effective amount of a pharmaceutical composition containing the crystalline forms. The patent therefore protects not only the compound itself (which would likely be covered by earlier composition of matter patents) but also specific, defined solid-state forms of that compound, and their use in pharmaceutical compositions and therapeutic methods. How is the Scope of Protection Defined? The scope of Patent 8,043,628 is primarily defined by the specific crystalline forms it claims and their therapeutic applications. What are the Defined Crystalline Forms? The patent defines at least two distinct crystalline forms, Form I and Form II. Form I: Characterized by specific diffraction peaks in an XRPD pattern at angles 2θ: 7.3, 14.7, 22.2, 23.2, and 27.8 degrees. Its DSC shows an endotherm at approximately 276.1°C. Its TGA indicates a weight loss of approximately 4.7% between 25°C and 180°C. Form II: Characterized by specific diffraction peaks in an XRPD pattern at angles 2θ: 6.7, 13.4, 17.0, 20.0, and 26.8 degrees. Its DSC shows an endotherm at approximately 292.1°C. Its TGA indicates a weight loss of approximately 4.2% between 25°C and 170°C. The precise definition of these forms using analytical techniques like XRPD, DSC, and TGA is crucial for establishing infringement and validity. The scope extends to any pharmaceutical composition containing these specific forms and any method of treating cancer using these forms. What Therapeutic Uses are Covered? The patent covers the use of these crystalline forms in treating "proliferative diseases," with a specific emphasis on "cancer." This encompasses the broad application of the drug in oncology. The claims are directed towards the administration of a therapeutically effective amount of a pharmaceutical composition containing the protected crystalline forms. What is the Patent Landscape for Palbociclib Crystalline Forms? The landscape surrounding Patent 8,043,628 involves several layers of patent protection, including earlier granted patents on the compound itself, potential later filings on improved formulations or manufacturing processes, and the intellectual property of competitors. What are the Key Patents Related to Palbociclib? The primary composition of matter patent for palbociclib is likely to have preceded Patent 8,043,628. A prominent patent in this area is U.S. Patent No. 7,244,720, also assigned to Pfizer Inc., titled "Pyrazolopyrimidines." This patent, filed on November 20, 2003, and granted on July 17, 2007, covers the compound itself (palbociclib) and various pharmaceutical compositions and methods of use for treating proliferative disorders. Patent 8,043,628 is a divisional or continuation application of the parent application that led to U.S. Patent No. 7,244,720, as indicated by its filing history and common assignee. Other relevant patent families may exist, potentially covering: Polymorphs and Solvates: As evidenced by 8,043,628, specific crystalline forms and solvates are often separately patented to extend market exclusivity and protect against generic competition by claiming forms not covered by earlier patents. Manufacturing Processes: Patents may cover novel or improved synthetic routes for producing palbociclib or its specific crystalline forms, aiming to provide manufacturing advantages or prevent competitors from using efficient production methods. Formulations: Patents might exist for specific drug delivery systems or formulations designed to enhance palbociclib's efficacy, stability, or patient compliance. New Indications: While not directly related to the crystalline forms, subsequent patents could claim new therapeutic uses of palbociclib beyond its current indications, further expanding the intellectual property portfolio. Who are the Key Players in the Palbociclib Patent Landscape? Pfizer Inc.: As the assignee of Patent 8,043,628 and likely the originator of palbociclib (Ibrance), Pfizer holds the primary intellectual property rights and has historically been the dominant player in this space. Generic Manufacturers: Companies seeking to market generic versions of palbociclib actively monitor patent expirations and the patent landscape. They may challenge existing patents through litigation or seek to develop non-infringing crystalline forms or manufacturing processes. Examples of companies that have engaged in generic drug development include Accord Healthcare, Mylan (now Viatris), and Teva Pharmaceuticals. Research Institutions: Academic and research institutions may hold patents related to novel aspects of palbociclib or its therapeutic applications, though these are less common for a drug that has reached commercialization by a major pharmaceutical company. How Do Different Patents Intersect? Patent 8,043,628 operates within the broader patent strategy for palbociclib. It complements the composition of matter patents by protecting specific physical forms that are critical for drug development and manufacturing. Generic manufacturers must navigate this complex web of patents. To launch a generic product, they typically need to: Wait for the expiration of key patents: This includes the composition of matter patent (e.g., U.S. Patent No. 7,244,720) and potentially patents covering specific crystalline forms (like 8,043,628), if they are still in force. Develop a non-infringing product: This could involve developing a different crystalline form of palbociclib not claimed by existing patents, or a different salt or solvate. They may also need to develop a distinct manufacturing process that does not infringe on any process patents. Challenge existing patents: Generic companies may initiate litigation to invalidate or find non-infringement of patents held by the innovator company. The expiration dates of these patents are critical for market entry. The earliest expiration would be based on the composition of matter patent, followed by patents on specific forms, formulations, and methods of use. What is the Current Status and Future Outlook? The patent protection for palbociclib, including Patent 8,043,628, directly influences market dynamics. What is the Exclusivity Period for Patent 8,043,628? United States Patent 8,043,628 has a term that typically extends 20 years from its filing date, subject to adjustments for patent term extension (PTE) and patent term adjustments (PTA). Given its filing date (which can be traced back through its parent applications), its effective market exclusivity period has been carefully managed by Pfizer. The original filing date for the parent application leading to U.S. Patent No. 7,244,720 was November 20, 2003. Patent 8,043,628 was filed as a divisional application on November 19, 2009. The standard patent term for 8,043,628 would therefore end in November 2029. However, PTE can extend this term for certain periods lost during regulatory review. How Does This Patent Affect Generic Competition? Patent 8,043,628, by protecting specific crystalline forms, creates an additional barrier for generic manufacturers. Even if the composition of matter patent expires, generic companies may be blocked from using the specific forms protected by this patent. They would need to demonstrate that their product does not infringe on the claims of 8,043,628, which often involves developing alternative crystalline forms. Litigation surrounding these crystalline form patents is common. Generic companies may challenge the validity of these patents or argue that their own crystalline forms are sufficiently different to avoid infringement. The outcome of such legal battles significantly impacts the timing and nature of generic market entry. What are the Implications for R&D and Investment? For R&D departments and investors, understanding this patent landscape is critical: For Innovators: It highlights the importance of protecting not just the drug molecule but also its critical solid-state forms to maximize market exclusivity and value. Investment in polymorph screening and characterization is essential. For Generic Developers: It necessitates thorough patent landscaping and freedom-to-operate analyses. Investment in developing novel, non-infringing crystalline forms, salts, or manufacturing processes is a key strategy. For Investors: Assessing the strength and remaining term of these patents, along with the potential for litigation, is crucial for valuing pharmaceutical assets and predicting market entry timelines for generics. The presence of patents on crystalline forms indicates a mature strategy by the innovator to extend market exclusivity. The ongoing patent litigation and the development of alternative crystalline forms will continue to shape the market for palbociclib-based treatments. Key Takeaways Patent 8,043,628 protects specific crystalline forms (Form I and Form II) of the active pharmaceutical ingredient in Ibrance (palbociclib), along with pharmaceutical compositions and therapeutic methods of use. This patent complements earlier composition of matter patents, extending market exclusivity for Pfizer Inc. by claiming specific solid-state properties crucial for drug manufacturing and performance. Generic manufacturers must navigate the expiration of this patent and avoid infringement of its claims, often requiring the development of alternative crystalline forms or manufacturing processes. The patent's term, extending to November 2029 (subject to adjustments), is a significant factor in the timeline for potential generic competition. Frequently Asked Questions 1. What is the primary difference between U.S. Patent No. 7,244,720 and U.S. Patent No. 8,043,628? U.S. Patent No. 7,244,720 protects the composition of matter for palbociclib and its general pharmaceutical uses. U.S. Patent No. 8,043,628 specifically protects particular crystalline forms of palbociclib (Form I and Form II) and their use in pharmaceutical compositions and treatment methods. 2. Can a generic company launch a palbociclib product if U.S. Patent No. 7,244,720 has expired but U.S. Patent No. 8,043,628 is still active? No, a generic company cannot launch a palbociclib product that infringes on the claims of U.S. Patent No. 8,043,628, even if U.S. Patent No. 7,244,720 has expired. Infringement of any valid, unexpired patent can block market entry. Generic companies would need to either wait for 8,043,628 to expire or develop a non-infringing crystalline form. 3. How are the crystalline forms in Patent 8,043,628 defined? The crystalline forms are defined by their unique analytical characteristics, including specific peak positions in X-ray powder diffraction (XRPD) patterns, and specific thermal events measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). 4. Does Patent 8,043,628 cover all possible crystalline forms of palbociclib? No, the patent claims specific crystalline forms, designated as Form I and Form II. It does not cover all theoretically possible crystalline forms of palbociclib. Other crystalline forms or solvates that are not claimed by this patent may exist and could be developed by generic manufacturers. 5. What is the significance of protecting specific crystalline forms in drug patents? Protecting specific crystalline forms is a strategy to extend the effective patent life and market exclusivity of a drug. These forms can have different physical properties, such as stability and solubility, which are critical for manufacturing and efficacy. By patenting these specific forms, the innovator company can prevent competitors from using the most stable or manufacturable forms of the drug, even after the original composition of matter patent expires. Citations [1] Pfizer Inc. (2011). U.S. Patent No. 8,043,628. Crystalline forms of 2-[[4-amino-3-(4-phenoxyphenyl)pyrazolo[3,4-d]pyrimidin-1-yl]methoxy]benzoic acid and their uses. Retrieved from USPTO Patent Full-Text and Image Database. [2] Pfizer Inc. (2007). U.S. Patent No. 7,244,720. Pyrazolopyrimidines. Retrieved from USPTO Patent Full-Text and Image Database. More… ↓ ⤷ Start Trial

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Details for Patent: 8,043,628

Summary for Patent: 8,043,628