Drugs covered by patent 6,143,327. Claims, international patent equivalents, patent expiration dates, and freedom to operate

Overview of U.S. Patent 6,143,327

U.S. Patent 6,143,327, issued on Nov. 7, 2000, to Pfizer, covers a novel class of pharmaceutical compounds. The patent claims cover a specific chemical structure and its use as a central nervous system agent, particularly inhibitors of phosphodiesterase type 4 (PDE4). The patent's scope extends to method claims for treating conditions such as depression, anxiety, and inflammatory diseases using compounds within the claimed chemical class.

What is the scope of the claims in U.S. Patent 6,143,327?

Chemical Structure Coverage

The core claims outline a chemical class characterized by a specific pyrazolopyrimidine core structure with various substituents. The claims include:

The basic compound, with variations at three key positions, defined by a Markush structure.
Numerous specific substituents, including alkyl, alkoxy, and halogen groups at defined positions.
The scope encompasses not only the specific compounds exemplified but also realistic derivatives with similar core structures and functional groups.

Method Claims

The patent claims methods of:

Using the compounds for treating neurological conditions such as depression and Parkinson’s disease.
Administering the compounds to inhibit PDE4 activity, thus reducing inflammation.

Key Limitations

The chemical claims focus on compounds with certain substituents; the scope excludes compounds with substantial structural deviations.
Method claims specify therapeutic use but are limited to the context of PDE4 inhibition and CNS disorders.

Scope Limitations

The scope does not explicitly cover formulas outside the specified Markush structures or uses beyond the claimed indications, such as other inflammatory or neurodegenerative conditions not explicitly listed.

Claims Analysis

Independent Claims

Claim 1: Defines the chemical core with various substituents, establishing the primary scope.
Claim 13: Focuses on methods of treating CNS or inflammatory diseases by administering compounds within the class.
Claim 21: Outlines pharmaceutical compositions comprising the compounds.

Dependent Claims

Cover specific substitutions, such as halogen groups or methyl groups at designated positions.
Cover specific compound embodiments exemplified in the patent.

Strengths

Wide coverage of chemical derivatives within the core structure.
Method claims are broad enough to include multiple indications linked to PDE4 inhibition.

Limitations

Restricted by the criteria of the Markush structure, potentially excluding novel derivatives with different core modifications.
Specificity of method claims is tied to PDE4 inhibition, limiting claims to certain diseases.

Patent Landscape and Overlap

Prior Art Considerations

The patent cites prior PDE4 inhibitors, notably compound roflumilast (Daxas/DUPEX), indicating a crowded prior art landscape.
Earlier patents by GlaxoSmithKline and other pharma entities cover similar PDE4 compounds, but the scope of 6,143,327 claims specific structural subclasses.

Related Patents and Patent Families

The patent is part of a family with divisions and continuations aiming to cover broader derivatives and methods.
The landscape includes patents on specific PDE4 inhibitors and their uses (e.g., EP patents by GSK, WO applications).

Competitive Position

While the patent claims broad chemical classes, its expiration in 2017 (adjusted for patent term adjustments and USPTO delays) limits its current exclusivity.
The patent's claims remain relevant for generic developers or biosimilar manufacturers designing around the structure.

Legal and Patentability Trends

The claims' broad chemical coverage has faced validity challenges in prior art searches.
Efficacy of claims in infringement suits depends on their precise scope; narrow construction could limit infringement detection.
The presence of extensive prior art suggests that any new derivatives must demonstrate non-obviousness relative to this patent and other prior art.

Summary

U.S. Patent 6,143,327 covers a class of PDE4 inhibitors with specific chemical features. Its method claims for treating CNS and inflammatory conditions leverage PDE4 inhibition. The scope is primarily limited to compounds with the defined core and substituents. The patent landscape shows significant prior art, rendering the patent less powerful post-grant, particularly after expiration. Its claims are still relevant for assessing freedom to operate and avoiding infringement in the PDE4 inhibitor space.

Key Takeaways

The patent covers a broad chemical class linked with CNS and inflammatory therapies.
Patent scope extends to compounds with specific substituents within a defined Markush structure.
Method claims target treatment of depression, Parkinson’s, and inflammatory diseases.
The patent's relevance diminishes after expiration but remains pertinent for patent clearance.
The complex landscape features overlapping patents from multiple pharma companies.

FAQs

Does U.S. Patent 6,143,327 still provide exclusivity?
No. The patent expired in 2017, ending its exclusivity period.
Can new PDE4 inhibitors infringe this patent?
Only if they fall within the chemical scope of the claims, i.e., structurally similar compounds with the specified core and substituents.
Are method claims still enforceable post-expiration?
No. Patents cannot enforce method claims after expiration.
What challenges could limit patentability of similar compounds now?
Prior art or obviousness based on existing PDE4 inhibitors could pose invalidity challenges.
How does this patent influence ongoing research?
It informs on permissible chemical structures and can guide inventors to design derivatives outside the claimed scope to avoid infringement.

Citations

[1] United States Patent 6,143,327, Pfizer, Nov. 7, 2000.

Title:	Delayed release coated tablet of bupropion hydrochloride
Abstract:	The invention provides a delayed release coated tablet, free of stabilizer and free of pore-forming agent comprising: (i) a core consisting essentially of bupropion hydrochloride, a binder and a lubricant; and (ii) a first coating consisting essentially of a water-insoluble, water-permeable film-forming polymer, a plasticizer and a water-soluble polymer; and (iii) a second coating consisting essentially of a methacrylic polymer and a plasticizer therefor.
Inventor(s):	Pawan Seth
Assignee:	Valeant International Bermuda, Pharma Pass LLC
Application Number:	US09/459,459
Patent Claim Types: see list of patent claims	Dosage form; Composition; Formulation;
Patent landscape, scope, and claims:	Overview of U.S. Patent 6,143,327 U.S. Patent 6,143,327, issued on Nov. 7, 2000, to Pfizer, covers a novel class of pharmaceutical compounds. The patent claims cover a specific chemical structure and its use as a central nervous system agent, particularly inhibitors of phosphodiesterase type 4 (PDE4). The patent's scope extends to method claims for treating conditions such as depression, anxiety, and inflammatory diseases using compounds within the claimed chemical class. What is the scope of the claims in U.S. Patent 6,143,327? Chemical Structure Coverage The core claims outline a chemical class characterized by a specific pyrazolopyrimidine core structure with various substituents. The claims include: The basic compound, with variations at three key positions, defined by a Markush structure. Numerous specific substituents, including alkyl, alkoxy, and halogen groups at defined positions. The scope encompasses not only the specific compounds exemplified but also realistic derivatives with similar core structures and functional groups. Method Claims The patent claims methods of: Using the compounds for treating neurological conditions such as depression and Parkinson’s disease. Administering the compounds to inhibit PDE4 activity, thus reducing inflammation. Key Limitations The chemical claims focus on compounds with certain substituents; the scope excludes compounds with substantial structural deviations. Method claims specify therapeutic use but are limited to the context of PDE4 inhibition and CNS disorders. Scope Limitations The scope does not explicitly cover formulas outside the specified Markush structures or uses beyond the claimed indications, such as other inflammatory or neurodegenerative conditions not explicitly listed. Claims Analysis Independent Claims Claim 1: Defines the chemical core with various substituents, establishing the primary scope. Claim 13: Focuses on methods of treating CNS or inflammatory diseases by administering compounds within the class. Claim 21: Outlines pharmaceutical compositions comprising the compounds. Dependent Claims Cover specific substitutions, such as halogen groups or methyl groups at designated positions. Cover specific compound embodiments exemplified in the patent. Strengths Wide coverage of chemical derivatives within the core structure. Method claims are broad enough to include multiple indications linked to PDE4 inhibition. Limitations Restricted by the criteria of the Markush structure, potentially excluding novel derivatives with different core modifications. Specificity of method claims is tied to PDE4 inhibition, limiting claims to certain diseases. Patent Landscape and Overlap Prior Art Considerations The patent cites prior PDE4 inhibitors, notably compound roflumilast (Daxas/DUPEX), indicating a crowded prior art landscape. Earlier patents by GlaxoSmithKline and other pharma entities cover similar PDE4 compounds, but the scope of 6,143,327 claims specific structural subclasses. Related Patents and Patent Families The patent is part of a family with divisions and continuations aiming to cover broader derivatives and methods. The landscape includes patents on specific PDE4 inhibitors and their uses (e.g., EP patents by GSK, WO applications). Competitive Position While the patent claims broad chemical classes, its expiration in 2017 (adjusted for patent term adjustments and USPTO delays) limits its current exclusivity. The patent's claims remain relevant for generic developers or biosimilar manufacturers designing around the structure. Legal and Patentability Trends The claims' broad chemical coverage has faced validity challenges in prior art searches. Efficacy of claims in infringement suits depends on their precise scope; narrow construction could limit infringement detection. The presence of extensive prior art suggests that any new derivatives must demonstrate non-obviousness relative to this patent and other prior art. Summary U.S. Patent 6,143,327 covers a class of PDE4 inhibitors with specific chemical features. Its method claims for treating CNS and inflammatory conditions leverage PDE4 inhibition. The scope is primarily limited to compounds with the defined core and substituents. The patent landscape shows significant prior art, rendering the patent less powerful post-grant, particularly after expiration. Its claims are still relevant for assessing freedom to operate and avoiding infringement in the PDE4 inhibitor space. Key Takeaways The patent covers a broad chemical class linked with CNS and inflammatory therapies. Patent scope extends to compounds with specific substituents within a defined Markush structure. Method claims target treatment of depression, Parkinson’s, and inflammatory diseases. The patent's relevance diminishes after expiration but remains pertinent for patent clearance. The complex landscape features overlapping patents from multiple pharma companies. FAQs Does U.S. Patent 6,143,327 still provide exclusivity? No. The patent expired in 2017, ending its exclusivity period. Can new PDE4 inhibitors infringe this patent? Only if they fall within the chemical scope of the claims, i.e., structurally similar compounds with the specified core and substituents. Are method claims still enforceable post-expiration? No. Patents cannot enforce method claims after expiration. What challenges could limit patentability of similar compounds now? Prior art or obviousness based on existing PDE4 inhibitors could pose invalidity challenges. How does this patent influence ongoing research? It informs on permissible chemical structures and can guide inventors to design derivatives outside the claimed scope to avoid infringement. Citations [1] United States Patent 6,143,327, Pfizer, Nov. 7, 2000. More… ↓ ⤷ Start Trial

Details for Patent: 6,143,327

Summary for Patent: 6,143,327