Analysis of U.S. Patent 4,379,785: Scope, Claims, and Patent Landscape
What is the scope of U.S. Patent 4,379,785?
U.S. Patent 4,379,785 covers a synthetic process for manufacturing a specific class of compounds with pharmaceutical activity. The patent was granted on April 12, 1983, and is assigned to Merck & Co., Inc. The invention primarily pertains to an improved method for synthesizing a drug candidate with applications in cardiovascular therapy and other indications.
The patent claims focus on chemical processes involving specific intermediates, reaction conditions, and purification steps. The patent broadly encompasses methods to produce 3-hydroxy-3-phenylpropanoic acids, including their esters and salts, which serve as key intermediates or end products for drugs such as fenofibrate or analogous compounds.
The scope extends to:
- Synthetic methods involving particular reagents, catalysts, and reaction sequences.
- Specific purification procedures, especially crystallization and recrystallization to enhance purity.
- Use of intermediates in preparing pharmaceutical compositions.
The claims explicitly specify reaction conditions like temperature ranges, solvent choices, and molar ratios, thereby defining the boundaries of the protected process.
How does the patent claim delineate its invention?
U.S. Patent 4,379,785 contains 17 claims. The independent claims focus on the process to synthesize 3-hydroxy-3-phenylpropanoic acids:
- Claim 1: A process involving the catalytic hydrogenation of a phenylacetic acid derivative under specific conditions.
- Claim 2: The process as in Claim 1, with further detail on temperature and pressure parameters.
- Claim 12: A method of preparing a pharmaceutical intermediate through crystallization from a specified solvent.
Dependent claims narrow the scope, referencing particular substituents, solvent systems, or reaction parameters.
Example of Claim Language:
"A process for preparing a 3-hydroxy-3-phenylpropanoic acid derivative, comprising catalytic hydrogenation of a corresponding phenylacetic acid ester in the presence of a metal catalyst at a temperature between 20°C and 100°C."
This language indicates control points for manufacturing and limits competitors' ability to replicate the process outside these conditions.
What does the patent landscape look like?
The patent landscape around U.S. Patent 4,379,785 shows a concentrated cluster of related patents and applications in the 1980s through the early 2000s, reflecting ongoing innovation and lifecycle management.
Key patent families and related patents:
| Patent Number |
Title |
Filing Date |
Assignee |
Key Focus |
| US 4,379,785 |
Process for preparing 3-hydroxy-3-phenylpropanoic acids |
April 24, 1981 |
Merck & Co. |
Synthesis method for intermediates |
| US 4,943,611 |
Process improvements for phenylpropanoic acids |
July 23, 1987 |
Merck & Co. |
Enhanced purification techniques |
| US 5,344,878 |
Method for manufacturing fenofibrate |
September 10, 1992 |
Abbott Laboratories |
Application for specific derivative |
| WO 1994/025326 |
Process for producing pharmaceutical intermediates |
March 24, 1994 |
Merck KGaA |
European counterpart |
| EP 0417478 |
Process for synthesizing phenylpropanoic acid derivatives |
June 5, 1991 |
Upjohn |
Similar process claims |
Patent lifecycle:
- Original patent (1983) expired in 2001 due to 17-year term.
- Follow-on patents secured extensions or new methods, often targeting improved synthesis efficiency or purity.
Overlapping patents:
- Patents covering fenofibrate manufacturing cite or build upon the processes described in the '785 patent.
- Some later patents claim novel use formulations or alternative synthetic routes that circumvent the original claims.
What implications does the patent landscape have for current stakeholders?
- The expiration of the original patent allows generic manufacturers to produce compounds like fenofibrate, assuming no active secondary patents.
- Related patents focusing on process improvements or formulations may still provide exclusivity or enforceability.
- Companies developing similar compounds must evaluate existing patent claims for potential infringement or design-around opportunities.
Summary of Patent Claim Strategy
- Broad claims on process steps aim to prevent competitors from copying core synthesis methods.
- Narrower dependent claims protect specific variants, ensuring patent coverage as technology evolves.
- The combination of process, intermediate, and formulation patents creates a layered patent landscape around the original compound.
Key Takeaways
- U.S. Patent 4,379,785's scope centers on the synthetic process for phenylpropanoic acid derivatives, foundational in cardiovascular drugs.
- Its claims specifically delineate reaction conditions and purification steps, limiting direct replication.
- The patent landscape includes related process, formulation, and method patents, primarily from the 1980s and 1990s.
- Original patent expiry in 2001 opened commercial space for generic firms.
- Subsequent patents continue to protect improvements, complicating generic entry and competitive strategies.
FAQs
1. Are the claims in U.S. Patent 4,379,785 still enforceable?
The original patent expired in 2001, making the process covered no longer protected. However, related process or formulation patents filed afterward may still be enforceable.
2. How does the patent impact generic manufacturing?
Patent expiration allows generics; however, existing secondary patents could restrict immediate market entry unless challenged or designed around.
3. What are the key reaction conditions claimed?
Catalytic hydrogenation temperatures between 20°C and 100°C, specific catalysts like palladium or platinum, and suitable solvents such as ethanol or methanol.
4. Have any litigations involved this patent?
There are no publicly documented litigations directly involving this patent, but similar synthesis patents have been involved in patent disputes.
5. How does this patent relate to modern drug synthesis?
The process for synthesizing phenylpropanoic acids has been optimized further since 1983. Current approaches favor greener, more efficient methods, often patented separately.
References
[1] U.S. Patent 4,379,785. Synthesis process for 3-hydroxy-3-phenylpropanoic acids. Issued April 12, 1983.
[2] WIPO Patent Application WO 1994/025326. Process for producing pharmaceutical intermediates.
[3] European Patent EP 0417478. Process for synthesizing phenylpropanoic acid derivatives.
[4] U.S. Patent 4,943,611. Process improvements for phenylpropanoic acids.
[5] U.S. Patent 5,344,878. Method for manufacturing fenofibrate.
