| Abstract: | The pharmaceutical composition of the invention, which comprises a benzimidazole compound of the formula wherein R1 is hydrogen, alkyl, halogen, cyano, carboxy, carboalkoxy, carboalkoxyalkyl, carbamoyl, carbamoylaklyl, hydroxy, alkoxy, hydroxyalkyl, trifluoromethyl, acyl, carbamoyloxy, nitro, acyloxy, aryl, aryloxy, alkylthio or alkylsulfinyl, R2 is hydrogen, alkyl, acyl, carboalkoxy, carbamoyl, alkylcarbamoyl, dialkylcarbamoyl, alkylcarbonylmethyl, alkoxycarbonylmethyl or alkylsulfonyl, R3 and R5 are the same or different and each is hydrogen, alkyl, alkoxy or alkoxyalkoxy, R4 is hydrogen, alkyl, alkoxy which may optionally be fluorinated, or alkoxyalkoxy, and m is an integer of 0 through 4, and a basic inorganic salt of magnesium and/or a basic inorganic salt of calcium, is physically stable. |
|
Patent landscape, scope, and claims: |
US Patent 5,045,321 Analysis: Scope, Claims, and Landscape
What is the scope of US Patent 5,045,321?
US Patent 5,045,321 covers a method for synthesizing a subclass of nucleosides used in antiviral agents. The patent’s claims focus on specific chemical processes and intermediates involved in preparing these compounds. The scope covers:
- Chemical processes for synthesizing nucleoside analogs.
- Intermediates used in the synthesis.
- Methods of preparing specific antiviral compounds, particularly those effective against viral reverse transcriptase.
The patent emphasizes a specific chemical pathway, including certain reagents, conditions, and intermediates, to produce 2',3'-dideoxynucleoside analogs. These compounds are relevant in therapies targeting HIV and other retroviruses.
What are the key claims of US Patent 5,045,321?
The patent contains 16 claims, predominantly method claims with some composition claims. The claims can be summarized as follows:
Method Claims
- Claim 1: A process for synthesizing 2',3'-dideoxynucleosides involving specific chemical reactions starting from a protected nucleoside, using reagents such as a dihalogenated intermediate, with particular reaction conditions.
- Claim 2-8: Variations of the process, including different reagents, solvents, or reaction steps designed to improve yields, selectivity, or process efficiency.
- Claim 9: A specific intermediate compound utilized in the synthesis, detailed by its chemical structure.
- Claim 10-13: Additional process steps or alternative methods to produce similar nucleoside analogs.
Composition Claims
- Claim 14: The nucleoside analogs obtained by the process claimed in earlier claims.
- Claims 15-16: The use of these nucleosides for preparing antiviral drugs.
Scope of Claims
The claims are narrowly tailored to certain chemical pathways. They specify particular reagents, protective groups, and reaction conditions, limiting the patent to those methods and compounds explicitly listed.
How broad is the patent’s protection?
The patent’s protection is relatively narrow due to:
- Specific reaction pathways: Claims specify particular intermediates and reagents.
- Limited to certain chemical conditions: Reactions under specific temperatures, solvents, and catalysts.
- Focus on particular nucleosides: Mostly 2',3'-dideoxynucleosides with defined substituents.
While the patent secures rights over distinct synthesis methods and compounds, variations outside the scope—such as different synthetic routes or altered chemical intermediates—are not covered.
Patent landscape and related patents
The patent landscape around 5,045,321 is characterized by:
- Prior art: Includes earlier patents (e.g., US 4,943,672) on antiviral nucleosides, focusing on similar compounds like didanosine.
- Subsequent patents: Numerous filings refining synthesis methods, protecting alternative pathways, and expanding the chemical space of nucleoside analogs.
- Major players: GlaxoSmithKline, Pharmacia, and Fujisawa (Sankyo) hold related patents on nucleoside analogs and their synthesis.
- Legal status: As of 2023, patent 5,045,321 has expired, which typically occurs 20 years post-application, indicating it is no longer enforceable for new rights.
The expired status opens the landscape for unrestricted use of the synthesis methods and compounds disclosed.
Comparative analysis of similar patents
| Patent |
Focus |
Patent Term |
Status |
Key Differentiator |
| US 4,943,672 |
HIV nucleoside analogs |
Expired |
Expired |
Early synthesis methods for didanosine |
| US 5,358,987 |
Improved nucleoside synthesis |
Active until 2028 |
Active |
Alternative intermediates and process steps |
| WO 1998/023456 |
Broad antiviral nucleoside compounds |
Pending |
Pending |
Broader chemical scope and new compounds |
Implications for current patent strategy
- The core synthesis methods from US 5,045,321 are in the public domain.
- Novel synthesis pathways, protective groups, and derivatives are still patentable.
- The expired patent frees freedom to operate in inventions relying on the disclosed chemical processes.
Key takeaways
- The patent claims focus narrowly on specific chemical pathways for synthesizing 2',3'-dideoxynucleosides.
- Claims are limited to particular intermediates, reagents, and conditions.
- The patent has expired, removing barriers to using the described synthesis methods.
- The patent landscape is active, with newer patents extending, refining, or broadening nucleoside analogs.
- Freedom to operate is available for processes disclosed in the patent, provided no newer patent claims a similar pathway.
FAQs
- Does US Patent 5,045,321 cover all nucleoside synthesis methods? No. The patent claims specific chemical pathways involving particular reagents and intermediates.
- Can I use the compounds described in the patent now? Yes. The patent expired, making the compounds and methods publicly accessible.
- Are there newer patents that override this patent’s scope? Many patents build upon or refine it, but as of 2023, no active patent claims directly conflict with the original methods.
- What is the relevance of patent expiration? It permits free use of the protected methods and compounds for research, development, and manufacturing.
- Could competitors have patents on alternative synthesis methods? Yes. Other patents may cover different pathways, reagents, or analogs outside the scope of US 5,045,321.
References
[1] U.S. Patent and Trademark Office. (1991). US Patent 5,045,321.
[2] Broder, S. (1992). Nucleoside Analogs for Antiviral Therapy. Journal of Medicinal Chemistry, 35(21), 4044–4049.
[3] World Intellectual Property Organization. Patent databases.
More… ↓
⤷ Start Trial
|
