United States Patent 5,622,721: A Detailed Analysis of Scope and Claims
Introduction
The United States Patent 5,622,721, titled "Enterically Coated Dosage Forms of Risedronate," is a significant patent in the field of pharmaceuticals, particularly in the delivery of bisphosphonic acid compounds. This patent, assigned to Merck & Co., Inc., was granted on April 29, 1997, and is crucial for understanding advancements in drug delivery systems.
Background of the Invention
Bisphosphonic acid compounds, such as risedronate, are widely used for treating bone diseases like osteoporosis and Paget's disease. However, these compounds can be challenging to administer orally due to their poor bioavailability and potential gastrointestinal irritation. The invention described in this patent addresses these issues by providing novel enterically coated dosage forms[1].
Summary of the Invention
The primary objective of this patent is to provide an enterically coated dosage form for the administration of risedronate, a bisphosphonic acid compound. The patent outlines several key aspects:
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Enterically Coated Dosage Forms: The patent describes compressed tablets, capsules, or other dosage forms that are enterically coated. This coating ensures that the drug is released in the lower gastrointestinal tract, bypassing the stomach and reducing gastrointestinal side effects[1].
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Delayed Release Formulations: The patent includes formulations where the drug is released in a delayed manner. This can be achieved through compressed tablets that are enterically coated, tablets containing enterically coated drug particles, or capsules with enterically coated drug particles[1].
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Stability-Enhancing Subcoat: To prevent the migration of the active agent from the core tablet to the surface of the enteric coating, a stability-enhancing subcoat is used. This subcoat minimizes the degradation of the drug before it reaches the intended site of release[1].
Claims of the Patent
The patent includes several claims that define the scope of the invention:
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Claim 1: This claim describes an enterically coated pharmaceutical dosage form comprising a core tablet containing risedronate, a stability-enhancing subcoat, and an enteric film that dissolves in the lower gastrointestinal tract[1].
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Subsequent Claims: These claims detail various embodiments, including different types of dosage forms (tablets, capsules), the composition of the enteric coating, and the method of preparing these dosage forms[1].
Technical Details
The patent provides detailed technical descriptions of how the enterically coated dosage forms are prepared and how they function:
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Enteric Coating: The enteric coating is designed to dissolve rapidly and completely once the dosage form enters the proximal portion of the lower gastrointestinal tract. This ensures that the drug is released at the intended site, maximizing its therapeutic effect while minimizing side effects[1].
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Stability-Enhancing Subcoat: This subcoat is crucial for maintaining the stability of the drug. It prevents the active agent from migrating to the surface of the enteric coating, thereby ensuring that the drug remains effective until it is released in the lower gastrointestinal tract[1].
Prior Art and Related Patents
The patent references several prior patents related to enterically coated dosage forms and drug delivery systems:
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U.S. Pat. No. 5,935,602: Also by Dansereau et al., this patent describes similar delayed release risedronate formulations[1].
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U.S. Pat. No. 5,431,920: By Bechard, this patent describes an enterically coated dosage form with a stability-enhancing subcoat, which is a precursor to the current invention[1].
Impact on Pharmaceutical Industry
The invention described in this patent has significant implications for the pharmaceutical industry:
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Improved Bioavailability: By ensuring that the drug is released in the lower gastrointestinal tract, the bioavailability of risedronate is improved, leading to better therapeutic outcomes[1].
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Reduced Side Effects: The enteric coating reduces gastrointestinal irritation, a common side effect of bisphosphonic acid compounds when taken orally[1].
Patent Landscape
The patent landscape surrounding U.S. Patent 5,622,721 is complex, with several related patents and ongoing innovations in drug delivery systems:
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Continuations and Divisions: The patent is part of a series of related patents and applications, indicating ongoing research and development in this area[1].
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Litigation and Licensing: The scope and claims of this patent could be subject to litigation and licensing agreements, given the importance of the technology in the pharmaceutical industry[3].
Key Takeaways
- Enterically Coated Dosage Forms: The patent introduces novel enterically coated dosage forms for risedronate, improving bioavailability and reducing side effects.
- Stability-Enhancing Subcoat: A critical component that maintains the stability of the drug until it is released in the lower gastrointestinal tract.
- Impact on Industry: The invention has significantly improved the administration of bisphosphonic acid compounds, enhancing therapeutic outcomes and patient compliance.
FAQs
Q: What is the primary objective of U.S. Patent 5,622,721?
A: The primary objective is to provide an enterically coated dosage form for the administration of risedronate, a bisphosphonic acid compound.
Q: How does the enteric coating work?
A: The enteric coating dissolves rapidly and completely once the dosage form enters the proximal portion of the lower gastrointestinal tract, ensuring the drug is released at the intended site.
Q: What is the role of the stability-enhancing subcoat?
A: The subcoat prevents the migration of the active agent from the core tablet to the surface of the enteric coating, maintaining the drug's stability until release.
Q: How does this patent impact the pharmaceutical industry?
A: It improves the bioavailability of risedronate and reduces gastrointestinal side effects, leading to better therapeutic outcomes and patient compliance.
Q: Are there related patents to U.S. Patent 5,622,721?
A: Yes, there are several related patents, including U.S. Pat. No. 5,935,602 and U.S. Pat. No. 5,431,920, which describe similar drug delivery systems.
Cited Sources
- US Patent for Enteric coated formulation of bishosphonic acid: Justia Patents.
- United States Patent (10) Patent No.: US 6,923,988 B2: Google Patents.
- Patent Claims and Patent Scope: Hoover Institution.
