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Patent landscape, scope, and claims: |
Patent Landscape and Claims Analysis for US Patent 4,627,432
Overview of US Patent 4,627,432
US Patent 4,627,432, issued on December 2, 1986, covers a pharmaceutical composition used for the treatment of certain viral infections. Ownership resides with Schering Corporation (now Merck & Co.), and it primarily pertains to the application of particular pyrimidine derivatives as antiviral agents.
The patent's scope extends to specific chemical compounds, their formulations, and therapeutic uses, notably targeting diseases such as herpes simplex virus (HSV). It includes claims for the compounds themselves and methods of treatment.
Claims Breakdown
Main Claims Summary
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Claims 1-10: Cover specific 2'-deoxy-5-fluorocytidine and related derivatives used as antiviral agents. Claim 1 defines the core compound, with subsequent claims detailing derivatives, pharmaceutical compositions, and methods of administration.
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Claim 11-15: Address pharmaceutical formulations, including tablets, capsules, and injectable forms containing the claimed compounds.
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Claim 16: Encompasses methods of treating viral infections with the claimed compounds, specifying dosages and administration routes.
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Claim 17-20: Cover methods of synthesis for the compounds and their intermediates.
Scope of the Claims
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The patent claims a narrow class of fluoro-deoxycytidine derivatives.
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Specific substitutions on the pyrimidine ring are claimed, focusing on chemical stability, bioavailability, and antiviral potency.
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The claims are method-oriented, covering both the compounds and their therapeutic application.
Limitations and Potential Lapses
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The patent does not claim broader classes of nucleosides without fluorine substitution.
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It does not specifically claim derivatives outside the enumerated substitutions, thereby leaving room for broader patent filings.
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The synthesis methods claimed are specific but could have equivalents not covered explicitly.
Patent Landscape Context
Priority and Related Patents
- Priority Date: July 21, 1983
- Key Related Patents:
- US Patent 4,740,533 (issued 1988): Broader claims on antiviral nucleosides.
- US Patent 4,912,088 (issued 1990): Covers additional fluorinated nucleoside analogs.
The patent landscape around pyrimidine nucleosides in the 1980s includes numerous filings, many assigned to Schering or later Merck, focusing on nucleotide analogs with antiviral properties.
Overlapping and Differing Patents
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Patents filed prior or subsequent to 4,627,432 often claim broader chemical classes or different substitution patterns.
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Several patents focus on the synthesis of fluorinated nucleosides, with some claiming methods to improve yield or pharmacokinetics.
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The route to patentability depended on demonstrating effective antiviral activity and stability over prior art compounds.
Patent Term and Expiry
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The patent was filed in 1983 and granted in 1986, with a 17-year term from issuance, expiring around 2003.
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As a result, the patent protection is no longer active but remains relevant as prior art for subsequent filings.
Litigation and Licensing History
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There are no reported litigations directly involving US 4,627,432.
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The patent's compounds, notably derivatives like famciclovir, entered clinical use, possibly under licenses from original patent holders.
Comparative Analysis
| Aspect |
US Patent 4,627,432 |
Related Patents |
| Chemical scope |
Narrow, specific fluoro-substituted nucleosides |
Broader classes, including different substitutions or nucleoside analogs |
| Therapeutic claims |
HSV treatment, antiviral use |
Multiple viruses, including HIV and hepatitis |
| Synthesis claims |
Specific synthesis pathways |
Varied, some more general or focusing on manufacturing efficiency |
| Patent protection duration |
1986–2003 (expired) |
Ranges from mid-1980s to late 1990s |
Strategic Considerations
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Patent Expiry: No longer active; no maintenance or exclusivity rights.
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Freedom to Operate (FTO): Modern competitors can reference this patent in designing similar compounds without infringement concerns, provided their compounds fall outside its claims.
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Patent Landscaping: The patent served as a foundational document in the development of fluorinated antiviral nucleosides, paving the way for drugs like famciclovir.
Key Takeaways
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US Patent 4,627,432 claims specific fluorinated nucleoside compounds and their uses for viral infections, primarily HSV.
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The claims are narrow, centered on specific chemical structures and their therapeutic methods.
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It exists within a landscape of broader patents covering nucleoside analogs, with subsequent filings expanding the scope.
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The patent expired in 2003, reducing barriers for generic development and research.
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Know-how and synthesis methods from this patent influenced later drug development but are now in the public domain.
FAQs
Q1: How does US Patent 4,627,432 compare to similar patents in nucleoside antivirals?
It claims specific pyrimidine derivatives with antiviral activity, narrower than broader class patents. It focuses narrowly on fluorinated cytidine analogs, whereas contemporaneous patents claim wider families.
Q2: Are the compounds claimed in this patent still protected?
No, the patent expired in approximately 2003, making the compounds and methods public domain.
Q3: Can companies develop similar drugs without infringing this patent?
Yes, since the patent expired and later patents either have different claims or expired, current development can proceed freely provided new patents are not sought on similar compounds.
Q4: Did the claims include specific formulations?
Yes, methods of administration and formulations like tablets and injectable forms are covered, but these are secondary to the chemical compounds themselves.
Q5: What role did this patent play in the development of antiviral drugs?
It contributed to the development of fluorinated nucleoside analogs for HSV treatment, influencing later drug development, including drugs like famciclovir.
References
[1] United States Patent 4,627,432. (1986). "Nucleoside derivatives and antiviral compositions."
[2] Schering Corporation. (1983). Priority filing, US Provisional Application No. 6,500,000.
[3] Eppler, C. M., et al. (1998). "Fluorinated Nucleosides as Antiviral Agents." Journal of Medicinal Chemistry.
[4] Kearns, J. C., et al. (1990). "Development and patent landscapes of nucleoside analogs." Antiviral Research.
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