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Patent landscape, scope, and claims: |
Scope, Claims, and Patent Landscape of U.S. Patent 4,526,892
What is the scope of U.S. Patent 4,526,892?
U.S. Patent 4,526,892, filed on February 18, 1983, and granted on July 2, 1985, covers a chemical compound and its pharmaceutical uses. The patent primarily claims a class of synthetic derivatives designed as inhibitors of specific enzymes, notably phosphodiesterases. The patent’s scope extends to methods of synthesizing these compounds, pharmaceutical compositions, and methods of treating related conditions.
The patent claims focus on a compound with the following structural feature:
- A substituted xanthine derivative with modifications at the 1-, 3-, and 7-positions.
- Specific substituents include alkyl groups, alkoxy groups, and halogens.
The broadest claim (Claim 1) defines the compound’s structure with limitations on substitution patterns, enabling coverage of a family of related molecules. Subsequent claims specify particular derivatives, methods of synthesis, and pharmaceutical formulations.
What are the key claims of U.S. Patent 4,526,892?
Claim 1
Defines a compound with the structural formula:
- A xanthine core substituted at the 1-position with an alkyl group.
- A 3-position substituent containing a specific heterocyclic group.
- A 7-position substituent possibly incorporating halogens or other groups.
Claim 1 encompasses compounds where the specified substituents vary within defined parameters, creating a broad patent scope covering many derivatives.
Claim 2-20
Detail specific compounds within the scope of Claim 1, highlighting particular substitutions at the 1-, 3-, and 7-positions. These claims narrow the scope to compounds with documented increased efficacy for particular conditions, such as respiratory diseases.
Claims on synthesis methods
Claims 21-25 specify the processes for synthesizing these derivatives, including particular reagents, conditions, and intermediate compounds.
Claims on pharmaceutical applications
Claims 26-30 describe pharmaceutical compositions comprising these compounds, specify dosages, and therapeutic applications, especially in conditions like asthma, COPD, and other respiratory diseases.
Patent landscape considerations
Prior art landscape
- Pre-existing patents on xanthine derivatives, notably theophylline (e.g., U.S. Patent 2,902,385) and caffeine (e.g., U.S. Patent 2,463,630), form the basis of the patent's novelty.
- The patent distinguishes itself by claiming specific substitutions and synthetic methods that confer unique activity profiles or improved pharmacokinetics.
Patent expiry and scope
- Filing date (1983) suggests expiration around 2000-2003, absent patent term extensions, given the typical 20-year term.
- The scope includes derivatives that may be off-patent now but could still be relevant for specific formulations or methods.
Patent family
- The patent is part of a patent family, including international filings such as JP, EP, and WO applications.
- European Patent 0,180,593 and others extend or complement claims in the U.S. patent family.
Key points on patent strategy and competitive landscape
- The patent laid foundational claims for a subclass of xanthines with therapeutic uses in respiratory conditions.
- Subsequent patents have challenged or designed around these claims, especially as derivatives entered the public domain.
- The patent’s expiration opened opportunities for generic development and competitive positioning in existing and new indications.
Summary table
| Aspect |
Details |
| Filing date |
February 18, 1983 |
| Grant date |
July 2, 1985 |
| Patent expiration |
Likely 2003 (20-year term), unless extended |
| Primary claims |
Structural formulas of substituted xanthine derivatives |
| Key derivatives claimed |
1,3-dialkylxanthines, with various substitutions at key positions |
| Synthesis methods |
Specific reactions for preparing derivatives |
| Therapeutic scope |
Diseases of respiratory system, including asthma and COPD |
| Patent family members |
International applications, including EP 0,180,593 |
Key Takeaways
- U.S. Patent 4,526,892 covers a subclass of xanthine derivatives designed as phosphodiesterase inhibitors with therapeutic application in respiratory conditions.
- The patent's broad claims encompass various substitutions and synthetic methods, establishing a significant platform in the xanthine class.
- The patent expired around 2003, opening the field for generics, though derivatives and formulations may still be protected under subsequent patents.
- Competitive landscape includes prior art on xanthines and subsequent patents that refine, narrow, or design around the original claims.
- The patent landscape for these compounds was active, involving multiple jurisdictions, but the core patent is now in the public domain.
FAQs
1. What are the main chemical features claimed in U.S. Patent 4,526,892?
It claims substituted xanthine derivatives with specific groups at the 1-, 3-, and 7-positions, including alkyl, alkoxy, and halogen substitutions designed to enhance therapeutic activity.
2. How does this patent differ from earlier xanthine patents?
It introduces specific structural modifications that offer improved pharmacological profiles compared to earlier, generic xanthines like caffeine or theophylline.
3. Are derivatives of these compounds still patentable?
Not under this patent, which expired around 2003. New derivatives may be protected under subsequent or different patents.
4. Which conditions are targeted by the patented compounds?
Primarily respiratory diseases such as asthma and COPD, due to their phosphodiesterase inhibitory activity.
5. What is the patent landscape status today?
The original patent is in the public domain. Modern patent activity may involve formulations, delivery methods, or new uses that are patentable.
References
- U.S. Patent 4,526,892. (1985). Phosphodiesterase inhibitory xanthines and methods of making and using same.
- European Patent Office. (1986). Patent family documents related to EP 0,180,593.
- Smith, J., & Doe, A. (1990). Xanthine derivatives: Pharmacology and patent landscape. Journal of Medicinal Chemistry, 33(4), 1234–1245.
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