United States Patent 5,567,817: A Detailed Analysis of Scope and Claims
Introduction
United States Patent 5,567,817, titled "Triazole antifungal agents," is a significant patent in the pharmaceutical industry, particularly in the field of antifungal treatments. This patent, granted to Pfizer, covers the invention of voriconazole, a widely used antifungal medication.
Background of the Invention
The patent was filed in response to the need for effective antifungal agents, particularly those belonging to the triazole class. Voriconazole, the primary compound described in this patent, has proven to be a potent and broad-spectrum antifungal agent[2][4].
Scope of the Patent
The scope of the patent is broad and encompasses several key aspects:
Chemical Compounds
The patent describes antifungal compounds of a specific formula, including voriconazole and its pharmaceutical salts. These compounds are characterized by their triazole structure and specific substituents, such as the 2,4-difluorophenyl group[1].
Synthesis Methods
The patent details various methods for preparing these compounds. This includes the reaction of a compound of formula II with a ketone of formula III, typically carried out at low temperatures (-80° to -50° C.) in an inert atmosphere using solvents like tetrahydrofuran[1].
Purification and Isolation
The patent also covers methods for the purification and isolation of these compounds, including fractional crystallization, chromatography, and the use of optically active acids for resolving racemates[1].
Claims of the Patent
The claims of the patent are comprehensive and include:
Compound Claims
The patent claims cover the individual stereoisomers of the compounds, as well as mixtures thereof. This includes both racemic and optically pure forms of voriconazole[1].
Method Claims
The patent claims methods for preparing these compounds, including specific reaction conditions and reagents. For example, the use of lithium diisopropylamide (LDA) as a base and tetrahydrofuran as a solvent is detailed[1].
Pharmaceutical Compositions
The patent also claims pharmaceutical compositions comprising these antifungal agents and pharmaceutically acceptable carriers. This is crucial for the formulation of voriconazole into usable drug products[4].
Patent Landscape
The patent landscape surrounding US 5,567,817 is complex and involves several related patents and processes.
Related Patents
Other patents, such as US 20080194820A1, describe alternative processes for preparing voriconazole. These processes aim to improve upon the original method by reducing the use of toxic and expensive reagents like zinc, lead, and iodine[2].
Improvements and Variations
Later patents, such as those described in the Justia Patents database, focus on optimizing the synthesis and purification of voriconazole. These improvements include single-vessel reactions and avoidance of extraneous chromatographic separation and crystallization techniques, leading to reduced manufacturing cycle time and improved product yield[4].
Impact on the Pharmaceutical Industry
The patent has had a significant impact on the pharmaceutical industry:
Clinical Use
Voriconazole, the primary compound covered by this patent, has become a standard treatment for various fungal infections, including those caused by Aspergillus and Candida species.
Economic Impact
The patent has generated substantial revenue for Pfizer and has influenced the development of other antifungal agents. The expiration of this patent has also led to the entry of generic versions of voriconazole into the market, increasing accessibility and reducing costs for patients[5].
Patent Scope Metrics
Research on patent scope metrics suggests that the breadth and clarity of patent claims are crucial. The independent claim length and count can be used to measure patent scope. In the case of US 5,567,817, the claims are detailed and specific, which has helped in maintaining the patent's validity and preventing overly broad interpretations[3].
Challenges and Controversies
The patent has faced challenges and controversies, particularly regarding the scope and breadth of its claims. Debates over patent quality and the alleged decrease in patent quality over the years have led to scrutiny of patents like US 5,567,817. However, the specific and detailed nature of its claims has generally supported its validity and enforceability[3].
Key Takeaways
- Broad Coverage: The patent covers a wide range of antifungal compounds, including voriconazole and its pharmaceutical salts.
- Detailed Synthesis Methods: The patent describes specific methods for synthesizing these compounds, including reaction conditions and reagents.
- Purification Techniques: It includes methods for purification and isolation, such as fractional crystallization and chromatography.
- Pharmaceutical Compositions: The patent claims pharmaceutical compositions comprising these antifungal agents.
- Impact on Industry: The patent has significantly influenced the development and use of antifungal treatments.
- Patent Landscape: The patent is part of a complex landscape with related patents and improvements aimed at optimizing synthesis and purification.
Frequently Asked Questions
Q: What is the primary compound covered by US 5,567,817?
A: The primary compound covered by this patent is voriconazole, an antifungal agent.
Q: How is voriconazole synthesized according to the patent?
A: Voriconazole is synthesized through the reaction of a compound of formula II with a ketone of formula III, typically at low temperatures in an inert atmosphere.
Q: What are the methods for purifying voriconazole described in the patent?
A: The patent describes purification methods including fractional crystallization, chromatography, and the use of optically active acids for resolving racemates.
Q: What is the significance of this patent in the pharmaceutical industry?
A: This patent has been crucial for the development and clinical use of voriconazole, a widely used antifungal medication.
Q: Are there any controversies surrounding this patent?
A: Yes, there have been debates over patent quality and the breadth of its claims, but the specific and detailed nature of its claims has generally supported its validity.
Cited Sources:
- US5567817A - Triazole antifungal agents - Google Patents
- US20080194820A1 - Process For Preparing Voriconazole - Google Patents
- Patent Claims and Patent Scope - Search eLibrary :: SSRN
- Process for the preparation of voriconazole - Justia Patents
- Voriconazole - Formulation Diary
