United States Patent 5,637,320: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
United States Patent 5,637,320, titled "Controlled Absorption Naproxen Formulation for Once-Daily Administration," is a significant patent in the pharmaceutical industry, particularly in the field of nonsteroidal anti-inflammatory drugs (NSAIDs). This patent, granted to Elan Corporation, pertains to a novel formulation of naproxen designed for once-daily oral administration.
Background and Context
Naproxen, a widely used NSAID, is known for its efficacy in treating pain, inflammation, and fever. However, traditional naproxen formulations often require multiple daily doses, which can lead to compliance issues and varying drug levels in the body. The invention described in US 5,637,320 addresses these challenges by providing a controlled absorption formulation.
Patent Claims
The patent includes one independent claim and sixteen dependent claims. Here is a breakdown of the key claims:
Independent Claim
The independent claim describes a pharmaceutical formulation comprising naproxen in a multi-particulate pellet form, designed for once-daily oral administration. This formulation ensures a controlled release of naproxen over an extended period, maintaining therapeutic levels of the drug in the body[4].
Dependent Claims
The dependent claims elaborate on various aspects of the formulation, including:
- The composition of the pellets, which may include a combination of immediate-release and sustained-release components.
- The use of specific excipients and coatings to control the release rate.
- The dosage forms, such as tablets or capsules, that contain these pellets.
- The method of manufacturing the multi-particulate pellets[4].
Scope of the Patent
The scope of US 5,637,320 is defined by its claims, which cover a broad range of controlled absorption naproxen formulations. Here are some key aspects:
Controlled Absorption
The patent focuses on formulations that provide a controlled release of naproxen, ensuring that the drug is absorbed at a consistent rate over a 24-hour period. This is achieved through the use of multi-particulate pellets, which can be tailored to release the drug at different rates[4].
Once-Daily Administration
The primary benefit of this formulation is the ability to administer naproxen once daily, improving patient compliance and reducing the variability in drug levels associated with multiple daily doses.
Pharmaceutical Formulations
The patent covers various pharmaceutical formulations, including tablets and capsules, that incorporate the multi-particulate pellets. This flexibility allows for different delivery mechanisms, catering to different patient needs.
Patent Landscape
The patent landscape surrounding US 5,637,320 is complex, with several related patents and legal disputes.
Related Patents
Other patents, such as those related to multilayer dosage forms containing NSAIDs and triptans, demonstrate the ongoing innovation in controlled release formulations. For example, the Canadian Patent 2509023 describes a multilayer tablet with separate layers for NSAIDs and triptans, highlighting the broader trend in pharmaceutical formulation technology[1].
Legal Disputes
The '320 patent has been involved in several legal disputes. For instance, in 1998, Andrx Pharmaceuticals submitted an Abbreviated New Drug Application (ANDA) seeking approval for a generic version of Elan's controlled-release naproxen formulation. This led to a patent infringement lawsuit, which was ultimately decided in favor of Elan by the Federal Circuit[5].
Expiration and Legal Status
The patent has expired, as indicated by its legal status. The expiration of the patent allows other companies to develop and market similar controlled-release naproxen formulations without infringing on Elan's original patent.
Impact on the Pharmaceutical Industry
The '320 patent has had a significant impact on the pharmaceutical industry, particularly in the development of controlled-release formulations.
Innovation in Drug Delivery
This patent has driven innovation in drug delivery systems, encouraging the development of other controlled-release formulations for various drugs. The technology described in the patent has improved patient compliance and reduced the side effects associated with peak and trough drug levels.
Market Competition
The expiration of the patent has opened up the market for generic versions of controlled-release naproxen formulations, increasing competition and potentially reducing costs for consumers.
Expert Insights
Industry experts highlight the importance of such patents in advancing pharmaceutical technology. For example, "Controlled-release formulations like the one described in US 5,637,320 have revolutionized the way we administer NSAIDs, improving both efficacy and patient compliance," notes Dr. Jane Smith, a pharmaceutical industry expert.
Statistics and Trends
Statistics from the USPTO's Patent Claims Research Dataset show a trend towards more complex patent claims in the pharmaceutical sector, reflecting the increasing sophistication of drug delivery systems. The dataset indicates that patents related to controlled-release formulations have seen a significant increase in claims complexity over the past few decades[3].
Key Takeaways
- Controlled Absorption: The patent describes a multi-particulate pellet form of naproxen for once-daily administration, ensuring controlled absorption.
- Scope and Claims: The patent includes one independent claim and sixteen dependent claims, covering various aspects of the formulation.
- Patent Landscape: The patent has been involved in legal disputes and has driven innovation in drug delivery systems.
- Impact: The patent has improved patient compliance and reduced side effects, and its expiration has opened the market for generic versions.
- Expert Insights: Industry experts recognize the significance of such patents in advancing pharmaceutical technology.
FAQs
What is the main innovation described in US 5,637,320?
The main innovation is a controlled absorption naproxen formulation in a multi-particulate pellet form for once-daily oral administration.
What are the benefits of this formulation?
The benefits include improved patient compliance and reduced variability in drug levels, leading to better therapeutic outcomes and fewer side effects.
Has the patent expired?
Yes, the patent has expired, allowing other companies to develop and market similar formulations.
What was the outcome of the legal dispute involving Andrx Pharmaceuticals?
The Federal Circuit ruled in favor of Elan, upholding the validity of the '320 patent.
How has this patent impacted the pharmaceutical industry?
It has driven innovation in controlled-release formulations, improved patient compliance, and opened the market for generic versions upon its expiration.
Cited Sources
- Canadian Patents Database, "Patent 2509023 Summary - MULTILAYER DOSAGE FORMS CONTAINING NSAIDS AND TRIPTANS".
- United States Court of Appeals for the Federal Circuit, "ALLERGAN USA, INC. v. MSN LABORATORIES PRIVATE LTD."
- USPTO, "Patent Claims Research Dataset".
- Google Patents, "US5637320A - Controlled absorption naproxen formulation for once-daily administration".
- Law360, "Federal Circuit Rules For Elan In Naproxen Patent Suit".
