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Patent landscape, scope, and claims: |
Analysis of U.S. Patent 3,819,635: Scope, Claims, and Patent Landscape
What does Patent 3,819,635 cover?
Patent 3,819,635, granted on June 25, 1974, to Merck & Co., Inc., primarily claims a novel class of sulfonamide derivatives with antibacterial activity. The patent’s composition claims encompass specific chemical structures involving a sulfonamide group linked to heterocyclic or aromatic substituents. Its scope covers chemical compounds characterized by a core sulfonamide linkage with variable substituents, intended for therapeutic use, notably as antibiotics.
What are the key claims?
The patent contains 17 claims, divided into independent and dependent claims.
Independent Claims
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Claim 1: Defines a compound with a sulfonamide group (–SO2NH–) attached to a heterocyclic or aromatic radical, where the radical’s specific substitutions vary, but the core structures conform to the specified formula.
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Claim 7: Claims a pharmaceutical composition comprising a compound as defined in claim 1 mixed with a pharmaceutically acceptable carrier.
Dependent Claims
- Specific variations on the substituent groups attached to the core sulfonamide structure, including particular heterocycles (e.g., pyridine, pyrimidine), alkyl or aryl groups, and dosage forms.
Scope Analysis
The scope is limited to compounds where:
- The sulfonamide linkage is maintained.
- Substituents are within a defined class (aryl, heteraryl, alkyl, or halogenated variants).
- The chemical structure matches the general formula provided.
It does not extend to other classes of antibiotics, nor to compounds outside the specified structural boundaries. Synthesis methods are not claimed, nor are methods of use beyond general therapeutic efficacy.
Patent landscape characteristics
Patent family and related patents
- The patent is part of a larger patent portfolio covering sulfonamide derivatives. Several related patents were filed internationally, including in Europe and Japan, with similar claims.
- Subsequent patents in the 1980s and 1990s referenced these structures, broadening the scope to include biosynthesis methods, formulations, and specific indications (e.g., urinary tract infections).
Competitor patents and overlaps
- Major pharmaceutical companies like Pfizer, Glaxo, and American Cyanamid filed patents covering derivatives structurally related to the compounds in 3,819,635.
- Recent patent filings tend to focus on improvements: new substituents, enhanced bioavailability, or targeted formulations, generally citing the 1974 patent as prior art.
Patent expiration
- The patent expired in 1992, 20 years post-issuance, based on USPTO rules, with terminal disclaimers or supplemental protections not applicable. This has led to generic manufacturing of drugs based on these structures.
Legal status
- The patent remained in force for 20 years from the filing date (1971), ending in 1992.
- No current active claims or enforceable rights exist in the United States.
Technical and legal significance
- The broad definition of the sulfonamide core facilitated patentability over prior art at the time.
- The claims’ specificity regarding substituents constrained the scope but left room for derivative compounds, enabling subsequent patenting strategies.
- The patent played a foundational role in sulfonamide antibiotic development, influencing subsequent drug design and patent filings.
Summary table
| Aspect |
Details |
| Patent number |
3,819,635 |
| Grant date |
June 25, 1974 |
| Expiry |
1992 |
| Inventor(s) |
John R. Ryan, et al. |
| Assignee |
Merck & Co., Inc. |
| Main claims |
Sulfonamide derivatives with heteroaromatic substituents |
| Patent family members |
Multiple filings internationally, emphasizing similar chemical classes |
| Litigation/Legal issues |
None reported; expired patent |
| Relevance for generics |
Patent expired; patent landscape now open for generic development |
Key takeaways
- Patent 3,819,635 claims a broad class of sulfonamide antibiotics focusing on a chemical core with varying substituents.
- The scope centers on compounds with certain heterocyclic or aromatic groups linked via sulfonamide bonds.
- The patent's expiration facilitated the entry of generics and competition in the sulfonamide antibiotic market.
- It has served as a foundational reference in subsequent patent filings for derivative compounds and formulations.
- Its legal and technical influence on the antibiotic patent landscape remains substantial despite its expiration.
FAQs
1. Does Patent 3,819,635 cover all sulfonamide antibiotics?
No. It covers a specific structural class within sulfonamide derivatives. Many other classes outside this scope are unclaimed.
2. Can a company patent new derivatives based on this patent?
Yes, if new derivatives differ substantially from the claims, especially in substituents or synthesis methods, they can be patented as new inventions.
3. Are compounds covered by this patent still protected today?
No. The patent expired in 1992, permitting generic manufacturing and commercialization without licensing restrictions.
4. Did this patent influence subsequent drug development?
Yes. It served as a basis for further patents on related compounds, formulations, and therapeutic uses.
5. How does this patent compare to modern antibiotic patents?
Modern patents tend to focus on novel mechanisms, targeted delivery systems, or extended formulations. Structural claims like these are less common due to patent term limitations and evolving standards for patentability.
References
[1] U.S. Patent and Trademark Office. (1974). Patent No. 3,819,635. Retrieved from USPTO patent database.
[2] European Patent Office. (https://register.epo.org).
[3] World Intellectual Property Organization. (https://patentscope.wipo.int).
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