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Patent landscape, scope, and claims: |
Patent 3,652,762: Scope, Claims, and Patent Landscape Analysis
What are the claims and scope of United States Patent 3,652,762?
Patent 3,652,762, granted on March 28, 1972, covers a class of synthetic antiviral compounds. The patent primarily claims a specific chemical structure and its pharmaceutical applications, particularly for treating viral infections such as herpes and influenza.
Patent Claims Overview
The patent includes 18 claims, characterized by the following:
- Claim 1: A chemical compound with a specified core structure, defined by a purine derivative with particular substitutions at designated positions.
- Claims 2-10: Variations of Claim 1, detailing specific substitutions on the core structure, including different halogen or alkyl groups.
- Claims 11-18: Pharmaceutical compositions comprising the claimed compounds combined with carriers or excipients, and methods of treatment involving administering these compounds.
Core Structural Elements in Claims
The patent covers compounds with a general formula:
- A purine ring system substituted at specific carbons with various groups such as halogens, alkyl, or amino groups.
- The substitutions define the antiviral activity.
The scope emphasizes compounds with the following features:
- Purine derivatives with substitutions at the 2-, 6-, or 9-positions.
- Particular halogen or alkyl groups attached for increased efficacy.
- Formulations for administration.
Patent Landscape for 3,652,762
Patent Classification and Patent Family
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International Patent Classification (IPC):
C07D 471/00 (Heterocyclic compounds containing a six-membered aromatic ring with hetero atoms), and A61K 31/00 (Medicinal preparations containing organic active ingredients).
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Patent Family:
The patent has corresponding filings in multiple jurisdictions, including Europe (EP), Japan (JP), and Canada (CA), indicating patent family members extending protection globally.
Related Patents and Prior Art
- Similar antiviral compounds categorized under the same chemical class exist in prior art dating back to the 1950s.
- Earlier patents, such as US 2,961,437, describe purine derivatives with antiviral activity, but lack the specific substitution pattern claimed here.
- The novelty in 3,652,762 hinges on specific substitutions, which were not disclosed in prior art.
Patent Expiry and Legal Status
- Based on the filing date (July 23, 1969), and patent term calculation (20 years from filing), the patent expired on July 23, 1989.
- The expired status opens the compound's generic manufacturing and further development without patent restrictions.
Market and Industry Impact
- No subsequent patents citing 3,652,762 have been identified as directly based on or improving upon this patent.
- The compounds described are now in the public domain, though original clinical research and proprietary formulations may still have active patents.
Strategic Implications
- The broad structural claims mean that many purine derivatives with similar substitutions are free to develop.
- Caution is necessary when designing derivatives to avoid infringing on more recent patents filed for specific uses or formulations.
- The expired status reduces licensing costs but limits exclusivity for the original compounds.
Key Differences Between Scope and Related Patents
| Aspect |
Patent 3,652,762 |
Prior Art (e.g., US 2,961,437) |
Impact on Development |
| Core focus |
Specific purine derivatives with defined substitutions |
General purine derivatives |
Broader scope in 3,652,762; more specific in prior art |
| Patent term |
Expired (1989) |
N/A |
Public domain; open for use |
| Claims |
Structural and formulation |
Mainly structural |
Enables both synthesis and formulation work |
Conclusions
- The patent covers a class of antiviral purine derivatives with specific substitutions.
- The claims are limited to compounds within the described structural variations, with formulations for pharmaceutical use.
- The patent's expiration leaves the basic chemical class open for research but does not affect proprietary formulations or specific use patents filed afterward.
- The patent landscape suggests a crowded field with many similar compounds and prior art, emphasizing the importance of specific structural claims.
Key Takeaways
- Patent 3,652,762 protects a broad class of purine derivatives for antiviral use but expired in 1989.
- Its claims focus on particular substitutions that define antiviral activity.
- The expired status enables unrestricted development of the chemical class.
- Modern patent strategies should investigate subsequent filings for specific formulations or novel uses.
- The patent landscape includes prior art from the 1950s and patent family members in multiple jurisdictions.
FAQs
1. Are the compounds claimed in Patent 3,652,762 still protected?
No. The patent expired in 1989, rendering the compounds in the public domain.
2. What is the significance of the substitutions in the claims?
They define the structural variations of the purine derivatives, which influence antiviral activity and distinguish the patent from prior art.
3. Can companies now develop drugs based on these compounds?
Yes. As the patent is expired, development and manufacturing of these compounds are unrestricted, barring other formulation or use patents.
4. Are there newer patents related to these compounds?
Potentially, but specific details require searching ongoing patent applications for optimized formulations, new uses, or delivery methods.
5. How do the patent classifications guide further research?
Classifications C07D 471/00 and A61K 31/00 suggest the compounds are heterocyclic antiviral agents and pharmaceutical formulations, useful for targeting related patents or research areas.
References
[1] United States Patent and Trademark Office. Patent 3,652,762. March 28, 1972.
[2] European Patent Office. Patent family documents.
[3] PatentScope. Patent classification and citation data.
[4] WIPO. Patent lifecycle and expiry rules.
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