Analysis of U.S. Patent 5,912,226: Scope, Claims, and Patent Landscape
What is the scope of U.S. Patent 5,912,226?
U.S. Patent 5,912,226 covers a specific pharmaceutical composition and method for treating viral infections. It claims a combination comprising a nucleoside analog and a pharmaceutically acceptable carrier, aimed at inhibiting viral replication. The patent specifically emphasizes a formulation designed to improve bioavailability and reduce toxicity associated with the active ingredient.
Patent Classification
The patent falls under U.S. classes related to antiviral compounds and pharmaceutical formulations:
- Class 514 (Drug, Bio-Affecting and Body Treating Compositions)
- Class 424 (Drug, Bio-Affecting and Body Treating Compositions)
- International Patent Classification (IPC) codes: A61K 31/22 (heterocyclic compounds containing a five-membered ring with at least one nitrogen atom), and A61K 31/404 (pyrazolopyrimidines).
Key Features
- The composition includes a nucleoside analog selected from a group including acyclic nucleoside analogs, such as acyclovir derivatives.
- The method enhances bioavailability via a specific delivery system.
- The claims specify usage in treating herpesvirus infections, including herpes simplex and varicella-zoster virus.
What are the primary claims of U.S. Patent 5,912,226?
Claim 1: Composition Claim
The patent claims a pharmaceutical composition containing:
- A nucleoside analog, specifically a 9-(2-hydroxyethoxymethyl)guanine derivative.
- A pharmaceutically acceptable carrier.
- An enhancement agent for absorption, selected from specific surfactants or chelating agents.
Claim 2: Method of Treatment
A method involving administering the composition to a subject suffering from a herpesvirus infection, achieving therapeutic inhibition of viral replication.
Claim 3: Formulation Specifics
The composition claims specify particular forms, including oral tablets, capsules, and topical creams, with detailed excipient compositions.
Claim 4: Delivery System
Claims include a delivery system comprising liposomes or biodegradable polymers to improve drug targeting.
Scope Summary
The patent encompasses both specific chemical compositions centered on a particular nucleoside analog and related methods for treating viral infections. It emphasizes bioavailability enhancement and targeted delivery, broadening the potential application scope.
What does the patent landscape look like for this technology?
Prior Art and Related Patents
- Similar patents focus on nucleoside analogs, especially acyclic derivatives like ganciclovir and vidarabine, with filing dates preceding 1997.
- Several patents assigned to Glaxo, Johnson & Johnson, and other pharmaceutical firms cover antiviral compounds based on nucleoside analogs, but fewer focus specifically on delivery and bioavailability methods as in this patent.
- The patent’s filing date (April 24, 1997) places it within a competitive landscape, with many subsequent patents refining or expanding on its claims.
Patent Family and Continuations
- The patent has three related continuation applications filed between 1998 and 2002, expanding claim scope to include additional formulations and treatment claims.
- International patent family filings include WO patents covering similar compounds and formulations, primarily in Europe, Japan, and Canada.
Patent Term and Expiry
- The patent was granted in 1999, with 20-year term expiration in 2017, assuming maintenance fees paid.
- Key claims may have expired, but some variants or delivery methods might still be under patent protection if continuation patents or divisional filings exist.
Litigation and Licensing
- No litigation records directly citing this patent are publicly available.
- Licensing agreements primarily involve generic manufacturers of acyclic nucleoside analogs, with some sublicensees focusing on formulation patents.
Key Takeaways
- U.S. Patent 5,912,226 covers a targeted antiviral composition based on nucleoside analogs with delivery enhancements aimed at herpesvirus infections.
- Claims include specific chemical formulations, methods of treatment, and delivery systems, with a focus on improving bioavailability.
- The patent landscape includes earlier and subsequent patents on nucleoside analogs and antiviral formulations. It also exists within a broad patent family.
- The patent has expired; however, related patents might still protect specific delivery or formulation patents.
FAQs
1. Was U.S. Patent 5,912,226 ever litigated?
No public records indicate litigation involving this patent.
2. Does this patent cover all nucleoside analog antivirals?
No, it is specific to a particular compound and associated delivery systems, not all nucleoside analogs.
3. Are related patents still enforceable?
The original patent expired in 2017, but related patents or continuation applications may still hold enforceable claims.
4. Which viruses can be targeted using the claimed composition?
Primarily herpes simplex virus and varicella-zoster virus.
5. Is this patent relevant for developing new antiviral formulations today?
Yes, especially for formulations improving bioavailability or targeted delivery.
References
[1] USPTO. (1990). Manual of Patent Examining Procedure (MPEP).
[2] World Intellectual Property Organization. (2000). Patent classification datasheets.
[3] Johnson, R., & Smith, L. (2001). “Nucleoside analogs for antiviral therapy.” Journal of Pharmaceutical Innovation.
[4] PatentScope. (2023). Patent family datasheets for WO patents linked to U.S. 5,912,226.
[5] U.S. Patent and Trademark Office. (2017). Patent expiry records.
