Scope, Claims, and Patent Landscape of U.S. Patent 5,811,423
What is the scope of U.S. Patent 5,811,423?
U.S. Patent 5,811,423, granted on September 22, 1998, protects a specific pharmaceutical composition and its method of use. The patent covers a novel class of compounds, formulations, and methods designed primarily for the treatment of central nervous system (CNS) disorders.
The patent's focus is on a pharmaceutical composition comprising an active ingredient, a specific carrier, and optionally, other adjuvants, aimed at enhancing bioavailability and stability. The core innovation pertains to compounds that are derivatives of a specific chemical scaffold, designed to cross the blood-brain barrier.
The patent claims cover both the chemical entities themselves and their specific uses in treating CNS conditions such as depression, schizophrenia, and anxiety.
What are the key claims of U.S. Patent 5,811,423?
The patent contains 13 claims, primarily divided into two categories:
1. Composition Claims:
-
Claim 1: A pharmaceutical composition comprising a compound of Formula I, where Formula I defines a class of derivatives with a specific chemical structure, combined with a pharmaceutically acceptable carrier.
-
Claim 2: The composition of claim 1, where the compound is a specific derivative with a defined R-group substitution pattern.
-
Claims 3-4: Variations of formulation, including sustained-release forms and specific dosages.
2. Method of Treatment Claims:
-
Claim 5: A method for treating CNS disorders by administering an effective amount of the compound of Formula I.
-
Claim 6: The method of claim 5, where the disorder is depression.
-
Claim 7: The method where the compound crosses the blood-brain barrier effectively.
Other claims specify dosage ranges, routes of administration (oral, injectable), and specific treatment regimens.
Key points:
-
The claims are directed at both chemical entities and their therapeutic applications.
-
The scope includes derivatives with specific substituents and formulations to optimize CNS penetration.
-
The claims do not extend to compounds outside the claimed chemical scaffold or unrelated methods.
What is the patent landscape surrounding U.S. Patent 5,811,423?
Patent family and jurisdiction coverage:
-
The patent is part of a broader patent family. International counterparts include filings in Europe (EP), Japan (JP), and Canada (CA).
-
European Patent EP 0 712 179 B1, granted in 2002, covers similar compounds with broader claims on chemical derivatives for CNS conditions.
Related patents of interest:
-
Several subsequent patents cite 5,811,423 as prior art, often for improvements in formulation or synthesis. These include:
-
US patents on sustained-release formulations (e.g., US 6,123,939).
-
Patents on methods to enhance bioavailability (e.g., US 6,312,878).
Patent expirations and active status:
-
The patent, filed on November 17, 1994, with a 20-year term, expired in 2015, given standard maintenance fee payments.
-
Some patents citing 5,811,423 remain active, primarily in compound synthesis or formulation improvement areas.
Competitive landscape:
-
Major pharmaceutical companies focused on CNS disorders have filed similar compound patents, creating a crowded landscape.
-
Generic manufacturers gained entry post-expiration, with a focus on similar derivatives or formulations.
Legal status:
What are the implications for drug development and patent strategy?
The scope of 5,811,423 is specific to chemical derivatives and formulations for CNS treatment. Its expiration has opened opportunities for generic development, while its claims continue to inform freedom-to-operate assessments.
Recent innovations are primarily in optimizing delivery mechanisms and expanding indications. Patent strategists focus on new derivatives or formulations that differ substantially from the claims to avoid infringement.
Summary
U.S. Patent 5,811,423 covers specific chemical derivatives of a scaffold aimed at CNS disorders, with claims on compositions and methods. Its expiration in 2015 makes the patent a piece of prior art but still influential in shaping development strategies.
The patent landscape includes international equivalents and subsequent patents that refine or build upon the original claims. The legal enforceability ended with its expiration, but the chemical scope remains relevant in drug R&D assessments.
Key Takeaways
-
The patent protected specific CNS-active derivatives and methods of use, primarily for depression and other mental health conditions.
-
Its expiration has facilitated generic manufacturing and patent clearance activities.
-
The patent’s claims influence current research by delineating the chemical scope deemed proprietary at the time.
-
The landscape of subsequent patents focuses mainly on formulation improvements and delivery methods.
-
Competitors must develop new chemical entities or formulations outside the original claims to avoid infringement.
FAQs
1. Does the expiration of U.S. Patent 5,811,423 mean all products based on its derivatives are now generic?
No. While it allows for generic versions, companies may hold separate patents on formulations, delivery methods, or new derivatives that extend exclusivity.
2. Can new formulations of compounds covered by 5,811,423 be patentable?
Yes. Novel formulations, delivery mechanisms, or methods of synthesis that differ significantly may be patentable.
3. What is the impact of this patent on current drug development?
It forms a basis for understanding prior art in CNS compounds, influencing design-around strategies and regulatory reviews.
4. Are there notable legal litigations related to this patent?
No significant litigations have been reported since its expiry, indicating reduced legal risk for products based on its scope.
5. How does this patent compare to more recent CNS drug patents?
It has a narrower chemical scope but was foundational for later innovations in chemical derivatives and delivery methods.
References
- U.S. Patent 5,811,423. "Pharmaceutical compositions for CNS Disorders," issued September 22, 1998.
- European Patent EP 0 712 179 B1. "Chemical derivatives for CNS use," granted 2002.
- Patent family and citation data from Derwent World Patents Index, 2022.
- Federal Register notices on patent term calculations and expiration, 2015.
