United States Patent 4,820,522: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
United States Patent 4,820,522, titled "Oral sustained release acetaminophen formulation and process," is a significant patent in the pharmaceutical industry, particularly in the field of drug delivery systems. This patent, granted to a pharmaceutical company, outlines a novel method and composition for an oral sustained release acetaminophen formulation. Here, we will delve into the scope, claims, and the broader patent landscape surrounding this invention.
Background of the Patent
The patent, filed in 1987 and granted in 1989, addresses the need for a sustained release formulation of acetaminophen, a widely used analgesic and antipyretic drug. The invention aims to provide a formulation that releases the drug slowly over a prolonged period, enhancing patient compliance and reducing the frequency of dosing[4].
Scope of the Patent
Purpose and Objectives
The primary objective of this patent is to develop a sustained release therapeutic composition of acetaminophen. The formulation is designed to release the drug slowly, ensuring a consistent therapeutic effect over an extended period. This is achieved through a combination of specific polymers and excipients that form a bioerodible matrix[4].
Key Components
- Active Ingredient: Acetaminophen is the therapeutically active medicament.
- Polymers: Hydroxyethyl cellulose and povidone (PVP) are used as matrix binding agents to achieve the sustained release effect.
- Excipients: Microcrystalline cellulose (wicking agent), pregelatinized starch (erosion promoter), magnesium stearate (lubricant), and colloidal silicon dioxide (glidant) are included to enhance the formulation's performance[4].
Claims of the Patent
The patent includes several claims that define the scope of the invention:
Independent Claims
- Claim 1 describes the sustained release therapeutic composition comprising acetaminophen, hydroxyethyl cellulose, and povidone, characterized by a slow release of the acetaminophen upon administration.
- Claim 2 specifies the method of preparing the sustained release formulation, including wet granulation, drying, milling, and compressing the granulation into tablets[4].
Dependent Claims
- These claims further detail the composition and process, including the proportions of the ingredients, the use of a bi-layer tablet with an immediate release layer and a sustained release layer, and the optional inclusion of additional excipients[4].
Patent Landscape
Prior Art and Novelty
The patent builds upon existing knowledge in the field of sustained release formulations but introduces a novel combination of polymers and excipients. The use of hydroxyethyl cellulose and povidone in specific proportions is highlighted as a major innovative feature[4].
International Patent Landscape
To understand the global impact, it is essential to search international patent databases. Resources such as the European Patent Office (EPO), Japan Patent Office (JPO), and the World Intellectual Property Organization (WIPO) provide access to international patent databases. This helps in identifying similar or related patents filed in other jurisdictions[1].
Related Patents and Applications
Using tools like the USPTO's Patent Public Search or the Common Citation Document (CCD) application, one can identify related patents and applications that cite or are cited by US 4,820,522. This analysis helps in understanding the broader patent landscape and potential infringement risks or opportunities for collaboration[1].
Impact on the Pharmaceutical Industry
Advantages of the Invention
- Bioerodible Tablets: The formulation ensures that no insoluble tablet-shaped device remains in the body after the drug is depleted, enhancing patient safety and compliance.
- High Drug/Matrix Binding Agent Ratios: This results in smaller tablets that are easier to swallow and more cost-effective.
- Adjustable Release Rates: The formulation allows for easy modification of the release rate by altering the levels of excipients, providing flexibility in drug delivery[4].
Market and Clinical Implications
The sustained release formulation of acetaminophen has significant market and clinical implications. It offers a more convenient dosing regimen, which can improve patient adherence to treatment plans. Clinically, it ensures a consistent therapeutic effect, reducing the risk of overdose or underdose associated with immediate release formulations.
Legal Status and Expiration
The patent has expired, as indicated by its legal status. This means that the technology and methods described in the patent are now in the public domain, and anyone can use or build upon this invention without needing to obtain a license from the original patent holder[4].
Conclusion
United States Patent 4,820,522 represents a significant advancement in the field of sustained release drug formulations. The detailed analysis of its scope, claims, and the broader patent landscape highlights its innovative contributions and impact on the pharmaceutical industry.
Key Takeaways
- Novel Formulation: The patent introduces a novel combination of polymers and excipients for a sustained release acetaminophen formulation.
- Bioerodible Tablets: The formulation ensures no residual tablet remains in the body after drug depletion.
- Adjustable Release Rates: The release rate can be modified by altering excipient levels.
- Expired Patent: The technology is now in the public domain.
FAQs
Q: What is the main purpose of United States Patent 4,820,522?
A: The main purpose is to develop a sustained release therapeutic composition of acetaminophen.
Q: What polymers are used in the sustained release formulation?
A: Hydroxyethyl cellulose and povidone (PVP) are used as matrix binding agents.
Q: How does the formulation ensure sustained release?
A: The combination of specific polymers and excipients forms a bioerodible matrix that releases the drug slowly over time.
Q: What are the advantages of this formulation?
A: It offers bioerodible tablets, high drug/matrix binding agent ratios, and adjustable release rates.
Q: Is the patent still in effect?
A: No, the patent has expired, and the technology is now in the public domain.
Sources
- USPTO: Search for patents - USPTO
- USA.gov: U.S. Patent and Trademark Office (USPTO) | USAGov
- SSRN: Patent Claims and Patent Scope
- Google Patents: Oral sustained release acetaminophen formulation and process - Google Patents
