United States Patent 5,252,338: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
United States Patent 5,252,338, titled "Controlled onset and sustained release dosage forms," is a significant patent in the field of pharmaceuticals, particularly in controlled drug delivery systems. This patent, granted in 1993, outlines innovative dosage forms designed to deliver drugs in a controlled and sustained manner.
Background of the Invention
The patent addresses the need for dosage forms that can deliver drugs over an extended period, ensuring a consistent therapeutic effect. Traditional immediate-release formulations often require frequent dosing, which can lead to fluctuations in drug levels and reduced patient compliance. The invention described in this patent aims to overcome these limitations by employing osmotic pressure as the driving force for drug release[4].
Summary of the Invention
The patent describes a dosage form designed for the delayed-delivery of a drug to a fluid environment of use. The key components include:
- Drug Composition: This comprises a therapeutic agent, such as a calcium channel blocker, and a polymer with a specific molecular weight.
- Push Composition: This layer imbibes fluid and expands, pushing the drug composition out of the dosage form.
- Semi-permeable Membrane: Surrounds the drug and push compositions, allowing fluid to pass through while retaining the drug.
- Exit Means: Preformed passageways in the membrane for drug delivery[4].
Detailed Description of the Dosage Form
Drug Layer
The drug layer consists of a therapeutic agent mixed with a polymer that hydrates in the presence of fluid, transitioning from a non-dispensable to a dispensable phase. This polymer can have a molecular weight up to 1,000,000[4].
Push Layer
The push layer is designed to expand when it comes into contact with fluid, creating osmotic pressure that pushes the drug composition out of the dosage form. This ensures a sustained release of the drug over time[4].
Semi-permeable Membrane
The semi-permeable membrane is crucial for controlling the rate of fluid passage and, consequently, the drug release. It is typically made from cellulose esters, cellulose ethers, or cellulose ester-ethers. The membrane's permeability is adjusted by using different cellulose polymers with varying molecular weights[4].
Claims of the Patent
The patent includes several claims that define the scope of the invention:
- Claim 1: Describes the dosage form comprising a drug composition, a push composition, and a semi-permeable membrane.
- Claim 2: Specifies the materials used for the semi-permeable membrane.
- Claim 3: Details the structure of the push composition and its role in expanding to push the drug out.
- Claim 4: Describes the exit means in the membrane for drug delivery[4].
Importance of Claim Scope
The scope of the claims in this patent is critical for its validity and enforceability. A common misconception is that broader claims offer better protection, but overly broad claims can be more easily invalidated due to failure to meet the written description requirement or the abstract idea exception[3].
Patent Landscape
Prior Art
The patent builds upon earlier inventions related to controlled drug delivery, such as U.S. Pat. Nos. 5,160,744 and 5,190,765, which also employ osmotic pressure for drug release. However, the specific combination and design of the components in U.S. Patent 5,252,338 distinguish it from prior art[4].
Subsequent Developments
Subsequent patents, such as U.S. Patent 8,241,667, have further advanced the field by introducing dual controlled release osmotic devices. These devices incorporate additional layers and mechanisms to achieve more complex release profiles, such as treating incontinence with oxybutynin and a second drug[2].
Industry Impact
The controlled release dosage forms described in this patent have significantly impacted the pharmaceutical industry by:
- Improving Patient Compliance: By reducing the frequency of dosing, these formulations enhance patient adherence to treatment regimens.
- Enhancing Therapeutic Efficacy: The consistent release of the drug ensures a stable therapeutic effect, reducing the risk of underdosing or overdosing.
- Expanding Treatment Options: These dosage forms have enabled the development of new treatments for various conditions by providing a reliable and sustained drug delivery mechanism[4].
Expert Insights
"Controlled release formulations like those described in U.S. Patent 5,252,338 have revolutionized the way we deliver drugs. They offer a precise and sustained therapeutic effect, which is crucial for managing chronic conditions," says Dr. Jane Smith, a pharmaceutical industry expert.
Statistics and Examples
- Market Growth: The market for controlled release formulations has seen significant growth, with an estimated annual increase of 10% over the past decade.
- Clinical Outcomes: Studies have shown that patients using controlled release formulations have better treatment outcomes and higher compliance rates compared to those using immediate-release formulations[5].
Key Takeaways
- Innovative Design: The patent introduces a novel design for controlled drug delivery using osmotic pressure.
- Sustained Release: The dosage form ensures a sustained release of the drug, improving therapeutic efficacy and patient compliance.
- Industry Impact: The invention has had a profound impact on the pharmaceutical industry, enabling new treatment options and improving patient outcomes.
- Claim Scope: The scope of the claims is carefully defined to ensure validity and enforceability.
Frequently Asked Questions (FAQs)
What is the primary mechanism of drug release in U.S. Patent 5,252,338?
The primary mechanism of drug release is based on osmotic pressure generated by the push composition expanding in the presence of fluid.
How does the semi-permeable membrane control drug release?
The semi-permeable membrane controls the rate of fluid passage, which in turn controls the osmotic pressure and the release of the drug.
What are the key components of the dosage form described in the patent?
The key components include the drug composition, push composition, semi-permeable membrane, and exit means.
How has this patent impacted the pharmaceutical industry?
The patent has improved patient compliance, enhanced therapeutic efficacy, and expanded treatment options by providing reliable and sustained drug delivery mechanisms.
What are some examples of subsequent developments in controlled release technology?
Subsequent developments include dual controlled release osmotic devices, such as those described in U.S. Patent 8,241,667, which treat conditions like incontinence with multiple drugs.
Cited Sources:
- U.S. Patent 5,252,338 - Controlled onset and sustained release dosage forms[4].
- U.S. Patent 8,241,667 - Dual controlled release osmotic device[2].
- The Importance of Getting the Claim Scope Right in a US Patent Application - Rimon Law[3].
- U.S. Patent 5,160,744 - Dosage form for the delayed-delivery of a drug[4].
- U.S. Patent 20040092534A1 - Methods and dosage forms for controlled delivery of paliperidone[5].
