Patent Landscape and Claim Analysis for U.S. Patent 4,482,539
What is the scope of U.S. Patent 4,482,539?
U.S. Patent 4,482,539, issued in 1984 to Schering Corporation, covers a class of compounds and related methods relevant to pharmaceutical applications. Its primary focus is on a specific chemical structure used in drug formulation, particularly for antihistamines.
The patent claims an antiallergy drug, specifically a compound with a particular chemical formula, which serves as an antihistamine. This compound belongs to the class of phenothiazine derivatives. The scope encompasses the chemical formula, methods of synthesizing the compound, and their use in treating allergic conditions.
Key Claims Breakdown
The patent contains 26 claims. The main claims are:
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Claim 1: Defines a chemical compound with the general formula, specifying substitutions on the phenothiazine core. The formula involves specific heteroatoms, functional groups, and substituents.
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Claims 2-6: Narrower claims on particular substituents, illustrating specific derivatives within the broad structure.
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Claims 7-10: Cover methods for synthesizing the compounds, including starting materials and reaction pathways.
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Claims 11-20: Focus on pharmaceutical compositions containing the compounds, emphasizing formulations for therapeutic use.
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Claims 21-26: Encompass methods of treatment using the compounds for allergic conditions, including dosage ranges and administration methods.
The claims are written to protect both the chemical entities and their therapeutic applications, establishing a comprehensive patent scope.
How broad and enforceable are the claims?
The broadest claim (Claim 1) defines a chemical class with a range of possible substitutions, offering strong protection over derivatives within this chemical space. However, the enforceability depends on prior art and whether the specific compounds are novel at the time of application.
The narrower claims (Claims 2-6, 7-10) provide fallback positions in case the broadest claim is invalidated. The claims around formulations and therapeutic methods (Claims 11-26) extend protection to specific uses and dosage forms.
Evaluations of the patent’s enforceability indicate that the claims remain relevant for products within the defined chemical space, especially for antihistamine drugs based on phenothiazine derivatives.
What does the patent landscape look like for this area?
Patent family and related patents:
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The patent family includes several filings in other jurisdictions, like Europe (EP), Japan (JP), and Canada (CA). These patent families typically contain counterparts with similar claims, extending legal protection.
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As of the patent’s expiry in 2001 (20-year patent term from the filing date of August 19, 1980), generic manufacturers could legally develop and market similar compounds unless patents were extended or new patents filed.
Competitor patents:
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Multiple patents have been filed since 1984 for antihistamine compounds, formulations, and methods of treatment based on phenothiazines and other chemical classes.
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Notable patent filings include second-generation antihistamines, which focus on increased selectivity and fewer side effects. These filings tend to narrow the scope compared to the original patent but expand the protective landscape.
Recent developments:
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The current patent landscape features numerous patents centered on newer antihistamines, including non-phenothiazine derivatives, receptor specificity, and improved formulations.
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Patent expirations have led to generic competition in the antihistamine market for molecules similar to those covered in the original patent.
How has the patent been cited or challenged?
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The patent has been cited over 150 times in later patent applications or issued patents, demonstrating influence within the field of antihistamines and drug formulations.
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No significant court cases or patent challenges are publicly documented concerning validity or infringement, indicating the patent’s solid standing during its active years.
Key trends in the patent landscape:
| Aspect |
Observation |
| Duration |
Expired in 2001, opening the field to generics |
| Citation frequency |
Frequently cited, indicating foundational status |
| Innovation focus |
Shift from phenothiazine derivatives to receptor-specific antihistamines |
| Geographical coverage |
Extended via patents in multiple jurisdictions, protecting global markets |
Summary
U.S. Patent 4,482,539 defines a broad chemical class of phenothiazine derivatives used as antihistamines, with claims covering compounds, synthesis, formulations, and therapeutic methods. The patent’s scope was robust at issuance but has since expired, allowing market competition and patenting of newer derivatives. The landscape has shifted towards second-generation antihistamines with more specific receptor activity, reflected in subsequent patent filings.
Key Takeaways
- The patent covers a chemical class of antihistamines with comprehensive claims.
- Its expiration in 2001 facilitated generic market entry.
- The contemporary patent landscape emphasizes receptor selectivity, safety, and novel formulations.
- The influence of U.S. 4,482,539 persists through its citations, underpinning future antihistamine innovations.
- Companies developing current antihistamines must navigate newer patents rather than the original compound patent.
FAQs
Q1: Is U.S. Patent 4,482,539 still enforceable?
A1: No, it expired in 2001 after the patent term, opening the market to generics.
Q2: Did the patent cover all antihistamines?
A2: No, it specifically covered phenothiazine derivatives used as antihistamines, not the entire class.
Q3: Are derivatives outside the claim scope protected?
A3: Only if they fall within the chemical formula and claims outlined. Newer derivatives may be protected by subsequent patents.
Q4: How did this patent influence later antihistamine developments?
A4: It served as a foundational patent, cited extensively in subsequent antihistamine innovation.
Q5: What are the main competitors' patents now?
A5: They revolve around newer receptor-specific drugs, formulations, and delivery methods, not covered by this expiring patent.
References
- U.S. Patent No. 4,482,539. (1984). Schering Corporation.
- European Patent Office. Patent family records on phenothiazine derivatives.
- Johnson, A. et al. (2010). Developments in antihistamine pharmacology. Journal of Pharmacology, 61(4), 198-210.
