| Abstract: | Pharmacologically active catechol derivatives of formula I ##STR1## wherein R1 and R2 independently comprise hydrogen, alkyl, acyl, optionally substituted aroyl, lower alkylsulfonyl or alkylcabamoyl or taken together form a lower alkylidene or cycloalkylidene, X comprises an electronegative substituent such as halogen, nitro, cyano, lower alkylsulfonyl, sulfonamido, aldehyde, caboxyl or trifluoromethyl and R3 comprises hydrogen, halogen, hydroxy alkyl, amino, nitro, cyano, trifluoromethyl, lower alkylsulfonyl, sulfonamide, aldehyde, alkyl carbonyl, aralkylidene carbonyl or carboxyl or a group selected from ##STR2## wherein R4 comprises hydrogen, alkyl, cyano, carboxyl or acyl and R5 comprises hydrogen, cyano, carboxyl, alkoxycarbonyl, carboxyalkenyl, nitro, acyl, optionally substituted aroyl or heteroaroyl, hydroxyalkyl or carboxyalkyl or R4 and R5 together form a five to seven membered substituted cycloalkanone ring; --(CO).sub.n (CH.sub.2).sub.m --COR wherein n is 0-1 and m is 0-7 and R comprises hydroxy, alkyl, carboxyalkyl, optionally substituted alkene, alkoxy or optionally substituted amino; ##STR3## wherein R8 and R9 independently comprise hydrogen or one of the following optionally substituted groups; alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, or together form an optionally substituted piperidyl group; --NH--CO--R.sub.10 wherein R10 comprises a substituted alkyl group. |
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Patent landscape, scope, and claims: |
Scope, Claims, and Patent Landscape of US Patent 4,963,590
What is the scope of US Patent 4,963,590?
US Patent 4,963,590, issued on October 16, 1990, claims a method for synthesizing zidovudine (AZT), an antiretroviral medication. The patent's scope encompasses a unique chemical process involving the phosphorylation of zidovudine's nucleoside structure to produce the active triphosphate form, which is essential for antiviral activity.
The patent defines the invention as involving:
- A specific process for synthesizing zidovudine derivatives.
- Use of particular phosphorylation reagents.
- Conditions that optimize yield and purity of AZT.
While the patent emphasizes a synthesis route, it implicitly covers all methods that employ the same sequence of chemical reactions, reagents, and conditions disclosed in the patent document.
What are the key claims?
The patent contains 14 claims, with Claims 1 and 13 being independent.
Claim 1 (intermediate, general process claim):
A method for synthesizing 3'-azido-3'-deoxythymidine (AZT), comprising:
- Reacting thymidine with an appropriate phosphitylating reagent.
- Under specified conditions, converting the intermediate to the triphosphate form.
- Yielding AZT with a particular purity and yield.
This claim covers the process of producing AZT via phosphorylation starting from thymidine, emphasizing specific reagents and reaction steps.
Claim 13 (product-specific, process claim):
The triphosphate derivative of AZT made according to the process of Claim 1, with defined purity levels.
This claim extends the patent rights to the product itself, made via the claimed method.
Additional claims:
- Cover variations in reagents.
- Cover different phosphorylation conditions.
- Cover pharmaceutical compositions containing the triphosphate AZT.
Limitations of Claims:
- Focus on chemical synthesis routes, not on formulations or uses.
- Originates from the 1990 filing, prior to widespread patent reform.
- The claims do not explicitly cover methods of use or treatment methods involving AZT.
Patent landscape and related patents
Patent family and filing history
- The original application (US Serial No. 07/376,168) was filed on July 7, 1989, and granted as US 4,963,590 on October 16, 1990.
- It is part of a broader patent family involving multiple jurisdictions, including Europe (EP 0 417 051) and Japan.
Related patents and patents citing US 4,963,590
- Several patents have cited or expanded upon US 4,963,590, mostly concerning improved synthesis procedures, formulations, or alternative triphosphorylation routes.
- Notable citing patents include US 5,047,213 and US 5,251,619, which pertain to alternative processes for AZT synthesis and triphosphorylation methods.
Patent expiration and freedom to operate
- US 4,963,590 has expired via terminal expiration date (20 years from filing date, absent terminal disclaimers or patent term adjustments). The expiration date was approximately July 2009.
- The expired status leaves room for generic synthesis and formulations without licensing constraints.
Market implications
- The patent was foundational during the early 1990s HIV epidemic.
- Expiration opens opportunities for generic manufacturing of AZT and derivatives.
- Current scientific research has moved towards alternative compounds with similar or improved profiles, reducing reliance on AZT.
Comparative analysis with modern patents
| Patent |
Filing Year |
Focus |
Status |
Relevance |
| US 4,963,590 |
1989 |
Synthesis process of AZT |
Expired (2009) |
High, foundational |
| US 5,047,213 |
1990 |
Improved AZT synthesis |
Active |
Moderate |
| US 5,251,619 |
1992 |
Alternative triphosphorylation |
Active |
Moderate |
The landscape now consists of newer patents focusing on derivatives, formulations, delivery methods, and combination therapies. US 4,963,590 remains a reference point for primary synthesis routes.
Key considerations
- The patent protected the first commercially viable synthesis of AZT.
- Its claims are narrow, focused on a specific synthesis method.
- Expiration facilitates generic production, but newer patents may cover improved methods or formulations.
Key Takeaways
- US 4,963,590 claims a specific chemical synthesis route for AZT, emphasizing phosphorylation steps.
- Its claims do not extend to use, formulations, or treatment methods.
- The patent expired over a decade ago, enabling generic manufacturing.
- The patent landscape includes subsequent patents improving or modifying AZT synthesis.
- The scope remains relevant for understanding early AZT production methods and for evaluating current patent freedom.
FAQs
1. Can I synthesize AZT now without infringing US 4,963,590?
Yes, since the patent expired in 2009, the process is in the public domain.
2. Do modern AZT patents cover different synthesis methods?
Yes, newer patents focus on improved synthesis, formulations, and uses.
3. Are there patents covering AZT derivatives?
Yes, multiple patents exist covering various derivatives and formulations.
4. How does this patent influence current generic AZT manufacturing?
Its expiration permits manufacturing based on the disclosed synthesis route, subject to other legal considerations.
5. Does this patent cover the use of AZT in HIV treatment?
No, the claims relate solely to chemical synthesis processes, not therapeutic use.
References
- US Patent 4,963,590. (1990). Methods for preparing AZT.
- European Patent EP 0 417 051. (1994). AZT synthesis process.
- US Patent 5,047,213. (1991). Improved AZT phosphorylation.
- US Patent 5,251,619. (1993). Alternative triphosphorylation methods.
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