United States Patent 4,925,860: A Detailed Analysis of Scope and Claims
Introduction
United States Patent 4,925,860, titled "Stable pharmaceutical composition of 3-(hydroxymethyl)-5,5-diphenylhydantoin disodium phosphate ester," is a significant patent in the pharmaceutical industry, particularly in the formulation of fosphenytoin sodium, a prodrug of phenytoin. This analysis will delve into the scope, claims, and the broader patent landscape surrounding this invention.
Background and Invention
The patent, filed on August 29, 1988, and granted on May 15, 1990, addresses the stability issues associated with fosphenytoin sodium, a prodrug that converts to phenytoin in the body. Phenytoin is used to treat convulsive states, but its water-insoluble nature poses challenges in formulation[1][4].
Key Claims
The patent primarily claims a stable pharmaceutical composition of 3-(hydroxymethyl)-5,5-diphenylhydantoin disodium phosphate ester, which is the chemical structure of fosphenytoin sodium. Here are the key aspects of the claims:
Composition
- The composition includes fosphenytoin sodium as the active ingredient.
- It requires the use of organic buffers, such as tromethamine, to maintain a pH range of 8.3 to 9.4, which is crucial for stability[1][4].
pH Adjustment
- The pH is adjusted using sodium hydroxide or hydrochloric acid to ensure it remains within the specified range, a requirement also endorsed by the US Pharmacopoeia (USP 28, 1995)[1].
Stability
- The formulation is designed to prevent the degradation of fosphenytoin sodium, which can occur due to alkaline hydrolysis in the presence of tromethamine. This is achieved by carefully controlling the pH and using appropriate buffers[1].
Scope of the Patent
The scope of the patent is narrowly defined to ensure the stability and efficacy of the fosphenytoin sodium formulation.
Specificity of Claims
The claims are specific in detailing the method and components necessary to achieve the stable composition. This specificity is crucial in patent law, as it distinguishes the invention from prior art and ensures that the claims are not too broad or abstract[2].
Exclusions
The patent excludes formulations that do not adhere to the specified pH range and buffer requirements, thereby preventing the monopolization of broader, less specific methods of stabilizing fosphenytoin sodium.
Prior Art and Novelty
The patent acknowledges prior art, particularly U.S. Pat. No. 4,260,769, which discloses derivatives of phenytoin. However, the current patent introduces a novel method of stabilizing fosphenytoin sodium through precise pH control and the use of specific buffers[1].
Impact on the Pharmaceutical Industry
This patent has significant implications for the pharmaceutical industry, particularly in the development of parenteral formulations.
Stability and Efficacy
By ensuring the stability of fosphenytoin sodium, the patent contributes to the reliability and efficacy of the drug in clinical settings. This stability is critical for maintaining the therapeutic effect and preventing adverse reactions due to degradation products[1].
Regulatory Compliance
The patent's adherence to USP standards for pH control ensures regulatory compliance, which is essential for the approval and marketing of pharmaceutical products.
Patent Landscape
The patent landscape surrounding U.S. Pat. No. 4,925,860 is characterized by several key factors:
Related Patents
Other patents, such as the one described in U.S. Patent Application 20070244074, have built upon this invention by further optimizing the stability of fosphenytoin sodium formulations. These subsequent patents often cite U.S. Pat. No. 4,925,860 as prior art and aim to address additional stability issues or improve the formulation process[1].
Legal Framework
The legal framework governing patents, particularly under 35 U.S.C. § 101, emphasizes the importance of specificity in patent claims. Patents must describe the method or process used to achieve the claimed result rather than simply claiming the outcome itself. This framework ensures that patents like U.S. Pat. No. 4,925,860 are protected for their innovative and specific contributions rather than broad, abstract ideas[2].
Conclusion
U.S. Pat. No. 4,925,860 is a pivotal patent in the pharmaceutical industry, providing a stable and effective formulation of fosphenytoin sodium. The patent's specificity in claims, adherence to regulatory standards, and impact on the stability and efficacy of the drug make it a significant contribution to the field.
Key Takeaways
- Stable Formulation: The patent ensures the stability of fosphenytoin sodium through precise pH control and the use of specific buffers.
- Regulatory Compliance: The formulation adheres to USP standards for pH control.
- Specificity of Claims: The patent claims are specific and detailed, distinguishing the invention from prior art.
- Impact on Industry: The patent contributes to the reliability and efficacy of fosphenytoin sodium in clinical settings.
- Legal Framework: The patent complies with the legal requirements under 35 U.S.C. § 101, emphasizing the importance of specificity in patent claims.
FAQs
What is the main claim of U.S. Pat. No. 4,925,860?
The main claim is for a stable pharmaceutical composition of 3-(hydroxymethyl)-5,5-diphenylhydantoin disodium phosphate ester, which is the chemical structure of fosphenytoin sodium.
Why is pH control important in this patent?
pH control is crucial to prevent the degradation of fosphenytoin sodium, which can occur due to alkaline hydrolysis in the presence of tromethamine.
What are the implications of this patent for the pharmaceutical industry?
The patent ensures the stability and efficacy of fosphenytoin sodium, contributing to its reliability in clinical settings and compliance with regulatory standards.
How does this patent comply with the legal framework under 35 U.S.C. § 101?
The patent claims are specific and detailed, describing the method and components necessary to achieve the stable composition, which distinguishes it from prior art and abstract ideas.
What is the significance of tromethamine in this patent?
Tromethamine is used as an organic buffer to maintain the pH range of 8.3 to 9.4, which is essential for the stability of the fosphenytoin sodium formulation.
Sources
- US Patent Application for Stable parenteral formulation of fosphenytoin sodium. Justia Patents.
- Patently Unclear: Why Result-Oriented Claims Don't Make the Cut Under 35 U.S.C. § 101. VK Law.
- Patent Claims Research Dataset. USPTO.
- US4925860A - Stable pharmaceutical composition of 3-(hydroxymethyl)-5,5-diphenylhydantoin disodium phosphate ester. Google Patents.
- U.S. Patent Small Claims Court. ACUS.
