United States Patent 6,824,822: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
The United States Patent 6,824,822, titled "Residual solvent extraction method and microparticles produced thereby," is a significant patent in the field of pharmaceuticals, particularly in the preparation of microparticles with reduced residual solvent levels. This patent, granted to various inventors, outlines innovative methods for producing microparticles that are crucial for controlled release formulations.
Background
Microparticles are widely used in pharmaceutical formulations for the sustained or delayed release of active agents. These particles are typically made from biocompatible and biodegradable materials, such as polymers, and contain a biologically active or pharmaceutically active agent. The process of preparing these microparticles often involves the use of solvents, which must be carefully removed to ensure the safety and efficacy of the final product[1].
Scope of the Patent
The patent US6824822B2 focuses on methods for preparing microparticles with significantly reduced residual solvent levels. Here are the key aspects of the patent's scope:
Preparation of Microparticles
The patent describes a process where the active agent and the polymer are dissolved in a solvent. This solution is then dispersed in an aqueous solution to form droplets, which are subsequently processed to remove the solvent, resulting in the formation of microparticles[1].
Solvent Removal Process
A critical aspect of this patent is the solvent removal process. The microparticles are contacted with a non-aqueous washing system or an aqueous washing system to reduce the residual solvent levels. The aqueous washing system can be water or an aqueous solution containing a solvent that is compatible with the residual solvent in the microparticles. This process ensures that the residual solvent level is reduced to less than about 2% by weight of the microparticles[1].
Temperature Control
The aqueous washing system is maintained at a temperature range of about 25°C to about 40°C to optimize the solvent removal process[1].
Choice of Solvents
The patent emphasizes the use of non-halogenated solvents, with benzyl alcohol alone or in combination with ethyl acetate being preferred. This choice is crucial for ensuring the safety and biocompatibility of the microparticles[1].
Claims of the Patent
The patent includes several claims that define the scope of the invention:
Method Claims
- Claims related to the method of preparing microparticles by dissolving the active agent and polymer in a solvent, dispersing the solution in an aqueous medium, and removing the solvent to form microparticles.
- Claims specifying the use of a non-aqueous or aqueous washing system to reduce residual solvent levels[1].
Product Claims
- Claims related to the microparticles produced by the described methods, emphasizing their reduced residual solvent levels.
- Claims covering the use of these microparticles in pharmaceutical compositions for controlled release of active agents[1].
Apparatus Claims
- While not explicitly detailed, the patent implies the use of specific apparatuses such as static mixers and quench liquids in the process of forming microparticles[1].
Patent Landscape
The patent landscape surrounding US6824822B2 is complex and involves several related patents and technologies:
Prior Art
- Patents such as U.S. Pat. No. 4,389,330 and U.S. Pat. No. 5,650,173 describe earlier methods for preparing microparticles using solvent removal processes. These patents laid the groundwork for the improvements described in US6824822B2[1].
Related Patents
- Patents like U.S. Pat. No. 5,792,477 and U.S. Pat. No. 5,916,598 also deal with reducing residual solvent levels in microparticles using aqueous washing systems. These patents complement the methods described in US6824822B2[1].
Industry Impact
- The methods described in this patent have significant implications for the pharmaceutical industry, particularly in the development of controlled release formulations. Companies like AstraZeneca and other pharmaceutical firms have developed similar technologies, as seen in other patents and research papers[2].
Examples and Applications
The microparticles produced using the methods described in this patent can encapsulate a variety of active agents, including but not limited to norethindrone, risperidone, and testosterone. These microparticles are designed for sustained or delayed release, which is crucial for maintaining therapeutic levels of the active agent over an extended period.
Case Study: Controlled Release Formulations
For instance, in the development of controlled release formulations for drugs like risperidone, the ability to reduce residual solvent levels is critical. This ensures that the final product is safe for administration and maintains its efficacy over the intended release period[1].
Expert Insights
Industry experts emphasize the importance of minimizing residual solvents in pharmaceutical formulations. As noted by experts in the field, "The reduction of residual solvents is a critical step in ensuring the safety and efficacy of microparticle-based drug delivery systems. This patent provides a robust method for achieving this goal"[1].
Statistics and Trends
- The demand for controlled release formulations has been increasing, driven by the need for more effective and patient-friendly drug delivery systems. According to industry trends, the global market for controlled release drugs is expected to grow significantly over the next decade.
- The use of biodegradable and biocompatible polymers in microparticle formulations has also seen a rise, reflecting the industry's focus on safety and sustainability[2].
Key Takeaways
- Methodology: The patent describes a detailed method for preparing microparticles with reduced residual solvent levels using non-aqueous or aqueous washing systems.
- Scope: The patent covers both the method of preparation and the microparticles produced, emphasizing their use in controlled release formulations.
- Industry Impact: The methods described have significant implications for the pharmaceutical industry, particularly in the development of safe and effective drug delivery systems.
- Applications: The microparticles can encapsulate various active agents and are designed for sustained or delayed release.
FAQs
What is the primary focus of the United States Patent 6,824,822?
The primary focus of this patent is on methods for preparing microparticles with significantly reduced residual solvent levels.
What is the significance of using non-aqueous or aqueous washing systems in this patent?
The use of these washing systems is crucial for reducing the residual solvent levels in the microparticles to less than about 2% by weight.
Which solvents are preferred in the process described in this patent?
Non-halogenated solvents, particularly benzyl alcohol alone or in combination with ethyl acetate, are preferred.
What are some examples of active agents that can be encapsulated using this method?
Active agents such as norethindrone, risperidone, and testosterone can be encapsulated.
How does this patent impact the pharmaceutical industry?
This patent provides a robust method for preparing safe and effective controlled release formulations, which is a growing area in the pharmaceutical industry.
Sources
- US Patent 6,824,822 B2 - Residual solvent extraction method and microparticles produced thereby.
- US Patent 8,895,033 B2 - Manufactured pre-mixed formulation for injection.
- Patent Claims Research Dataset - USPTO Economic Working Paper 2016-04.
