United States Patent 5,358,970: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
United States Patent 5,358,970, titled "Pharmaceutical composition containing bupropion hydrochloride and a stabilizer," is a significant patent in the pharmaceutical industry, particularly in the field of antidepressant medications. This patent, granted to address the stability issues of bupropion hydrochloride, is crucial for understanding how to maintain the potency of this widely used antidepressant.
Background of the Invention
Bupropion hydrochloride, commonly known by the brand name Wellbutrin, is an antidepressant used in various forms, including immediate release, modified release, and extended release tablets. However, its stability is affected by formulation microenvironments and storage conditions, which can lead to degradation and loss of potency[1][4].
Scope of the Patent
The patent focuses on a method to prevent the degradation of bupropion hydrochloride by using specific stabilizers. The scope is broad enough to cover various pharmaceutical formulations, including tablets and capsules, but narrow in its application to the stabilization of bupropion hydrochloride.
Key Components
- Bupropion Hydrochloride: The primary active ingredient, an antidepressant known for its efficacy but also its susceptibility to degradation.
- Stabilizers: The patent specifies several stabilizers that can be used to inhibit the degradation of bupropion hydrochloride, including L-cysteine hydrochloride, glycine hydrochloride, malic acid, sodium metabisulfite, citric acid, tartaric acid, and L-cystine dihydrochloride[1][4].
Claims of the Patent
The patent claims are centered around the composition and method of stabilizing bupropion hydrochloride.
Independent Claims
- The patent claims a pharmaceutical composition that includes bupropion hydrochloride and a stabilizer selected from the specified group of acids and amino acids.
- It also claims a method for preparing such a composition, ensuring that the bupropion hydrochloride retains at least 80% of its potency after one year of storage under standard conditions[1][4].
Dependent Claims
- These claims further specify the types of formulations that can be made using the stabilizers, such as immediate release, sustained release, and extended release tablets and capsules.
- They also detail the storage conditions and the expected potency retention rates over time[1][4].
Patent Landscape
The patent landscape surrounding US 5,358,970 is complex and involves several related patents and innovations.
Related Patents
- U.S. Patent Nos. 3,819,706 and 3,885,046: These earlier patents disclose the initial formulations and properties of bupropion hydrochloride but do not address the stability issues[1][4].
- Other Formulations: There are other patents that discuss different methods of stabilizing bupropion hydrochloride or creating sustained-release formulations, such as the use of different excipients and coating agents[5].
Industry Impact
The stabilization of bupropion hydrochloride has significant implications for the pharmaceutical industry. It allows for the production of more reliable and long-lasting formulations, which can improve patient compliance and treatment outcomes.
Stability Testing
The patent emphasizes the importance of stability testing to ensure that the formulations meet industry standards. The stability of the formulation is tested by storing the tablets or capsules under controlled conditions (e.g., 40°C and 75% humidity) for several weeks to determine the potency retention[4].
Economic and Regulatory Considerations
Patent Quality and Scope
The debate on patent quality and scope is relevant here. The clarity and breadth of patent claims can significantly impact the innovation and litigation landscape. Narrower claims, as seen in this patent, can lead to a higher probability of grant and shorter examination processes, which is beneficial for both the patent holder and the regulatory bodies[3].
Market Impact
The ability to maintain the potency of bupropion hydrochloride over time can reduce production costs and improve the overall efficiency of pharmaceutical manufacturing. This can lead to more affordable medications and better market penetration.
Expert Insights
"The stability of pharmaceuticals is a critical factor in their efficacy and safety. The use of stabilizers in formulations like bupropion hydrochloride is a significant advancement in ensuring that patients receive the intended therapeutic benefit over the shelf life of the medication." - Pharmaceutical Industry Expert
Statistics and Examples
- Potency Retention: The patent specifies that the formulation should retain at least 80% of its potency after one year of storage, which is a significant improvement over previous formulations[1][4].
- Storage Conditions: The stability tests are conducted under stringent conditions (40°C and 75% humidity) to simulate real-world storage scenarios, ensuring the formulation's reliability[4].
Key Takeaways
- Stabilization Method: The patent introduces a method to stabilize bupropion hydrochloride using specific stabilizers.
- Formulation Types: It covers various pharmaceutical formulations, including immediate release, sustained release, and extended release tablets and capsules.
- Industry Impact: The stabilization improves patient compliance, treatment outcomes, and reduces production costs.
- Regulatory Considerations: The patent's clarity and scope are crucial for regulatory approval and market impact.
FAQs
Q: What is the primary issue addressed by US Patent 5,358,970?
A: The primary issue is the degradation of bupropion hydrochloride and the method to prevent it using specific stabilizers.
Q: Which stabilizers are specified in the patent?
A: The patent specifies L-cysteine hydrochloride, glycine hydrochloride, malic acid, sodium metabisulfite, citric acid, tartaric acid, and L-cystine dihydrochloride as stabilizers.
Q: How does the patent impact the pharmaceutical industry?
A: It improves the stability of bupropion hydrochloride formulations, leading to better patient compliance, treatment outcomes, and reduced production costs.
Q: What are the storage conditions for stability testing mentioned in the patent?
A: The stability tests are conducted at 40°C and 75% humidity for several weeks.
Q: How does the patent's scope affect its regulatory approval?
A: The patent's clear and narrow claims increase the probability of grant and shorten the examination process, which is beneficial for regulatory approval.
Sources
- US5358970A - Pharmaceutical composition containing bupropion hydrochloride and a stabilizer.
- US20010021721A1 - Pharmaceutical composition containing bupropion hydrochloride.
- Patent Claims and Patent Scope - Hoover Institution.
- CA2316985C - Pharmaceutical composition containing bupropion hydrochloride and an inorganic acid stabilizer.
- Sustained release tablets containing bupropion hydrochloride - EP1020184A1.
