United States Patent RE37314: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
United States Patent RE37314, titled "Pyrimidine derivatives," is a reissue of U.S. Pat. No. 5,260,440, which was originally issued on November 8, 1993. This patent is significant in the pharmaceutical industry, particularly in the treatment of hypercholesterolemia, hyperlipoproteinemia, and atherosclerosis.
Scope of the Invention
Field of the Invention
The patent pertains to 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors. These compounds play a crucial role in the biosynthesis of cholesterol and are essential in the treatment of various lipid-related disorders[1].
Compounds and Their Structure
The patent describes a class of pyrimidine derivatives that inhibit HMG-CoA reductase. These compounds are defined by the formula (I), where various substituents such as lower alkyl, aryl, or aralkyl groups are attached to the pyrimidine ring. The specific structure includes variables such as R1, R2, R3, and R4, which can be hydrogen, lower alkyl, or aryl, and X, which can be sulfur, oxygen, sulfonyl, or imino with possible substituents[1].
Claims of the Patent
Pharmaceutical Composition
The patent claims include pharmaceutical compositions comprising the pyrimidine derivatives. These compositions are designed to inhibit HMG-CoA reductase, thereby suppressing the biosynthesis of cholesterol. This makes them useful in treating hypercholesterolemia, hyperlipoproteinemia, and atherosclerosis[1].
Specific Compounds
One of the key compounds covered under this patent is rosuvastatin calcium, which is an antihypercholesterolemic drug. Rosuvastatin calcium is described by its structural formula and is used in the treatment of atherosclerosis and related lipid disorders[2].
Preparation Processes
Amorphous Rosuvastatin Calcium
The patent also discloses processes for the preparation of amorphous rosuvastatin calcium. This involves dissolving rosuvastatin sodium salt in water and adding calcium chloride to form the amorphous calcium salt. However, prior art approaches have been criticized for their commercial impracticality due to difficulties in isolating the product in high purity and the presence of unwanted diastereomeric impurities[2][4].
Crystalline Forms
In addition to the amorphous form, the patent mentions processes for preparing crystalline forms of rosuvastatin, such as Form A, which involves warming the amorphous form in a mixture of water and acetonitrile and then cooling the solution[2][4].
Patent Landscape
Prior Art and Obviousness
The patent landscape has evolved significantly since the issuance of RE37314, particularly with the Supreme Court decision in KSR International Co. v. Teleflex Inc. This decision changed the standard for obviousness, making it more challenging for patents to withstand validity challenges. Patents granted under the old standard, including those like RE37314, may be more vulnerable to challenges based on obviousness[3].
Commercial and Practical Considerations
The commercial viability of the processes described in RE37314 has been a point of contention. The prior art approaches for preparing amorphous rosuvastatin calcium are not commercially feasible due to issues with product purity and isolation. This has led to the development of alternative processes that address these challenges[2][4].
Impact on the Pharmaceutical Industry
Treatment of Lipid Disorders
The compounds and processes described in RE37314 have been instrumental in the development of treatments for lipid-related disorders. Rosuvastatin calcium, in particular, has become a widely used medication for reducing cholesterol levels and preventing atherosclerosis[2].
Intellectual Property Considerations
The patent has significant implications for intellectual property strategies in the pharmaceutical industry. Companies must reassess the value of their patents in light of the KSR decision and ensure that their patents reflect a high level of novelty and practical novelty advantages to maintain their commercial value[3].
Key Takeaways
- HMG-CoA Reductase Inhibitors: The patent covers pyrimidine derivatives that inhibit HMG-CoA reductase, crucial for cholesterol biosynthesis.
- Rosuvastatin Calcium: A key compound covered under this patent, used in treating hypercholesterolemia and atherosclerosis.
- Preparation Processes: Includes methods for preparing amorphous and crystalline forms of rosuvastatin calcium.
- Patent Landscape: The patent's validity and commercial viability have been influenced by changes in patent law, particularly the KSR decision.
- Commercial Impact: Significant in the treatment of lipid disorders and has commercial implications for pharmaceutical companies.
FAQs
What is the main purpose of the compounds described in US Patent RE37314?
The main purpose of the compounds described in US Patent RE37314 is to inhibit HMG-CoA reductase, thereby suppressing the biosynthesis of cholesterol and treating hypercholesterolemia, hyperlipoproteinemia, and atherosclerosis.
How is amorphous rosuvastatin calcium prepared according to the patent?
Amorphous rosuvastatin calcium is prepared by dissolving rosuvastatin sodium salt in water and adding calcium chloride.
What are the challenges associated with the prior art approach for preparing amorphous rosuvastatin calcium?
The prior art approach is commercially impractical due to difficulties in isolating the product in high purity and the presence of unwanted diastereomeric impurities.
How has the KSR decision impacted the patent landscape for RE37314?
The KSR decision has made it more challenging for patents to withstand validity challenges based on obviousness, potentially affecting the vulnerability of patents like RE37314.
What is the significance of rosuvastatin calcium in the pharmaceutical industry?
Rosuvastatin calcium is a widely used medication for reducing cholesterol levels and preventing atherosclerosis, making it a significant compound in the treatment of lipid-related disorders.
Sources
- USRE37314E1 - Pyrimidine derivatives - Google Patents
- US20070191318A1 - Process for the preparation of amorphous rosuvastatin calcium - Google Patents
- PATENT FACTOR INDEX REPORT - IQPC
- WO2005040134A1 - Process for the preparation of amorphous rosuvastatin calcium - Google Patents
