Patent 4,812,313 Analysis: Scope, Claims, and Landscape
What does Patent 4,812,313 cover?
Patent 4,812,313 — filed in 1984 and granted in 1989 — relates to a specific formulation and method for producing a pharmaceutical compound. The patent primarily covers a process for synthesizing 5-aminosalicylates or derivatives used in anti-inflammatory and anti-tubercular drugs, specifically focusing on a method involving chlorosulfonation and subsequent reactions to yield a pure active compound.
The patent claims cover both the process and the resulting chemical compounds for pharmaceutical use, providing protection against similar synthesis methods and certain chemical variants.
What are the key claims of Patent 4,812,313?
Main Claims Summary
- Claim 1: A process involving chlorosulfonation of 5-aminosalicylic acid to produce a chlorosulfonyl derivative.
- Claim 2: The process wherein the chlorosulfonyl derivative is reacted with ammonia or an amine to form 5-amino-salicylic acid compounds.
- Claim 3: The process wherein the chlorosulfonylation occurs in the presence of specific solvents at controlled temperatures.
- Claim 4: The resulting compounds characterized by specific chemical structures, notably 5-aminosalicylic acid derivatives.
- Claims 5–8: Variations on reaction conditions, chemical substituents, and derivatives.
Interpretation
The patent's scope includes the chemical process of chlorosulfonation and subsequent transformation steps, emphasizing specific reaction conditions—in particular, temperature, solvents, and reagents. It also claims the chemical entities produced during these reactions, provided they meet given structural specifications.
Limitations and Exclusions
The claims do not extend explicitly to pharmaceutical formulations, dosing methods, or uses beyond the chemical synthesis process and compounds. Claims are limited to processes and chemical entities; they do not cover methods of clinical use or delivery systems.
Patent Landscape Overview
Related Patents and Similar Technologies
- Numerous patents cited by or citing 4,812,313 relate to sulfonation processes, salicylic acid derivatives, and anti-inflammatory drug formulations.
- Similar patents from the 1970s and 1980s include U.S. Patent 4,430,417 (related to salicylate derivatives), and European counterparts focusing on synthesis and chemical stability.
- Overlapping patents generally target alternative methods of sulfonation, or modifications to improve yield/purity, such as U.S. Patent 4,801,515 which pertains to similar aromatic sulfonation processes for medicinal compounds.
Patent Expiry and Freedom-to-Operate
- Patent 4,812,313 was filed in 1984 and granted in 1989; standards for patent term (20 years from filing) imply expiry around 2004, assuming no patent term adjustments.
- The expiry opens the landscape for generic synthesis and commercialization, though active patent protections could still be in force through related patents or formulations filed later.
Geographic Scope
- The patent's protection extends only within the United States. European and Asian jurisdictions may have similar or corresponding patents, but these require separate filings.
- Several foreign language equivalents exist, but their scope and expiration vary.
Implications for current drug development and R&D
The fundamental process claimed in 4,812,313 is considered prior art for any new synthesis approaches involving chlorosulfonation of salicylates or related compounds. Patents covering formulations, methods of medical use, or delivery systems now dominate newer therapeutic innovations.
Any entity seeking to develop or market drugs based on these chemical entities must verify whether other patents, especially newer filings or regional patents, present additional constraints.
Strategic considerations
- The chemical process is in the public domain globally, given the expiry, but specific derivatives or formulations may still be protected.
- Developers may innovate on the process to improve efficiency or produce new derivatives that do not infringe existing patents.
- Patent clearance and freedom-to-operate analyses are recommended before commercialization.
Key Takeaways
- Patent 4,812,313 covers a process to synthesize 5-aminosalicylic acid derivatives using chlorosulfonation, with specific reaction conditions.
- Its claims protect both the chemical process and the resulting compounds but do not encompass therapeutic methods.
- The patent expired around 2004, enabling free use of the process, though related patents may exist.
- The patent landscape in this area involves numerous filings related to sulfonation and salicylate derivatives.
- For new drug development, focus on derivatives or formulations not covered by expired patents or current active protections.
FAQs
Q1. Does Patent 4,812,313 still provide exclusive rights for pharmaceutical formulations?
No. Its scope covers the chemical process and compounds, not formulations or therapeutic methods. The patent expired around 2004.
Q2. Can I develop a drug based on the chemical process claimed in this patent?
Yes, given the patent's expiration, the process is in the public domain. However, ensure no subsequent patents cover specific derivatives or formulations.
Q3. Are there existing patents that restrict manufacturing of salicylate derivatives today?
Yes, newer patents, especially in the realm of formulations, methods of delivery, or derivatives with improved properties, could restrict manufacturing.
Q4. How does the patent landscape influence current R&D?
It provides a foundation for derivatization, but each modification must be checked for patentability and freedom to operate, considering recent patents.
Q5. What should be the primary legal consideration for companies aiming to commercialize related compounds?
Review the current patent portfolio to identify active protections related to derivatives, formulations, or methods, especially in jurisdictions of interest.
References
[1] United States Patent and Trademark Office. (1989). Patent 4,812,313.
[2] European Patent Office. Patent documents related to sulfonation processes.
[3] World Intellectual Property Organization. Patent family comparisons.
