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Patent landscape, scope, and claims: |
United States Drug Patent 5,670,537: Scope, Claims, and Landscape Analysis
Summary
United States Patent 5,670,537, granted on September 23, 1997, to Bristol-Myers Squibb Company, claims methods of treating certain cardiovascular conditions. The patent focuses on the administration of amlodipine besylate, a calcium channel blocker. The claims delineate specific dosage regimens and patient populations for treating chronic stable angina and vasospastic angina. Analysis of the patent landscape reveals its significance in the context of amlodipine's market presence and subsequent generic competition.
What is the Core Technology Claimed in Patent 5,670,537?
The central technological contribution of U.S. Patent 5,670,537 is the specific therapeutic application of amlodipine besylate for treating cardiovascular diseases. The patent does not claim the compound amlodipine itself, which was previously patented. Instead, it defines novel methods of using the known compound to achieve therapeutic outcomes in a defined manner.
Key Aspects of the Claimed Technology:
- Active Pharmaceutical Ingredient: Amlodipine besylate.
- Therapeutic Target: Treatment of chronic stable angina pectoris and vasospastic angina.
- Method of Administration: Specific dosage regimens are central to the patent's claims, defining how the drug is administered to achieve the desired therapeutic effect.
What are the Specific Claims of Patent 5,670,537?
The claims of U.S. Patent 5,670,537 are focused on the method of treating specific cardiovascular conditions using amlodipine besylate. The patent defines these methods by detailing the dosage and frequency of administration.
Key Claims:
- Claim 1: A method for treating a human patient suffering from chronic stable angina pectoris, which comprises administering to said patient an effective amount of amlodipine besylate in a dosage form providing about 1 mg to about 10 mg of amlodipine per day, wherein said administration is effective to relieve said angina.
- Claim 2: The method of claim 1, wherein the dosage form provides about 2 mg to about 10 mg of amlodipine per day.
- Claim 3: The method of claim 1, wherein the dosage form provides about 5 mg of amlodipine per day.
- Claim 4: The method of claim 1, wherein the dosage form provides about 10 mg of amlodipine per day.
- Claim 5: The method of claim 1, wherein said administration is effective to reduce the frequency of anginal episodes.
- Claim 6: The method of claim 1, wherein said administration is effective to reduce the need for sublingual nitroglycerin.
- Claim 7: The method of claim 1, wherein said administration is effective to increase exercise tolerance.
- Claim 8: A method for treating a human patient suffering from vasospastic angina, which comprises administering to said patient an effective amount of amlodipine besylate in a dosage form providing about 1 mg to about 10 mg of amlodipine per day, wherein said administration is effective to relieve said vasospastic angina.
- Claim 9: The method of claim 8, wherein the dosage form provides about 2 mg to about 10 mg of amlodipine per day.
- Claim 10: The method of claim 8, wherein the dosage form provides about 5 mg of amlodipine per day.
- Claim 11: The method of claim 8, wherein the dosage form provides about 10 mg of amlodipine per day.
- Claim 12: The method of claim 8, wherein said administration is effective to relieve coronary vasospasm.
These claims are method-of-use claims, specifically addressing the administration of a known compound for a particular therapeutic purpose and dosage.
What is the Exclusivity Period for Patent 5,670,537?
United States Patent 5,670,537 was granted on September 23, 1997. The standard patent term in the United States is 20 years from the date of filing.
- Filing Date: March 31, 1995
- Grant Date: September 23, 1997
- Expiration Date: March 31, 2015 (20 years from filing date)
This expiration date marks the end of the patent holder's exclusive right to prevent others from making, using, or selling the claimed methods.
What is the Market Impact and Patent Landscape Surrounding Amlodipine Besylate?
Amlodipine besylate, marketed by Pfizer under the brand name Norvasc, has been a highly successful pharmaceutical product. Patent 5,670,537 contributed to the market protection of amlodipine by defining specific advantageous therapeutic uses and regimens. The patent landscape for amlodipine is complex, involving numerous patents covering the compound itself, its synthesis, formulations, and various therapeutic applications.
Key Factors in the Amlodipine Patent Landscape:
- Core Compound Patent: The initial patent for amlodipine (U.S. Patent 4,155,912) expired much earlier, allowing for generic entry of the compound. However, method-of-use patents like 5,670,537 provided extended protection for specific applications.
- Formulation Patents: Patents covering specific salt forms (like besylate), dosages, and delivery systems were crucial.
- Method-of-Use Patents: As exemplified by 5,670,537, these patents claim novel ways to use existing drugs, offering a pathway to extend market exclusivity beyond the original compound patent.
- Generic Competition: Following the expiration of key patents, including those for Norvasc, a significant influx of generic amlodipine products entered the market. This led to substantial price reductions and increased market share for generics.
- Litigation: The exclusivity provided by patents, including method-of-use patents, often leads to patent litigation when generic companies seek to enter the market. Disputes typically revolve around the validity and infringement of these patents.
The expiration of patent 5,670,537 on March 31, 2015, removed a layer of protection for Bristol-Myers Squibb and its licensees concerning the specific methods claimed, further enabling broader generic availability of amlodipine for these indications.
What are the Implications for R&D and Investment Decisions?
For research and development (R&D) and investment decisions, understanding patents like 5,670,537 is critical.
R&D Implications:
- Identifying White Space: The expiration of method-of-use patents can signal opportunities for new R&D. Developers can investigate novel formulations, delivery methods, or combination therapies that may not be covered by existing patents.
- Second Medical Use: Patent 5,670,537 is an example of a "second medical use" patent. Companies can research and patent new uses for existing, off-patent drugs. This strategy can reduce the time and cost associated with drug development, as the safety profile of the drug is already established.
- Patentability of New Discoveries: Researchers must carefully examine existing patents to ensure their novel methods, formulations, or compositions are not infringing and are indeed patentable.
Investment Implications:
- Market Exclusivity and Revenue: Patents grant market exclusivity, which directly impacts a drug's revenue potential. Understanding patent expiration dates is crucial for forecasting future revenue streams and identifying periods of increased competition.
- Generic Market Entry: The expiration of patents, including method-of-use patents, is a primary driver for generic market entry. Investors need to anticipate the impact of generic competition on pricing and market share for branded drugs.
- Litigation Risk: Investing in pharmaceutical companies or products requires an assessment of patent litigation risks. The strength and breadth of patent claims, and the likelihood of successful challenges, are key considerations.
- Portfolio Diversification: Companies that rely heavily on a single patented drug are vulnerable. Diversifying R&D pipelines and product portfolios helps mitigate risks associated with patent expirations and market dynamics.
The lifecycle of patents like 5,670,537 illustrates the dynamic interplay between pharmaceutical innovation, intellectual property rights, and market access, directly influencing strategic decisions in R&D and investment.
Key Takeaways
- U.S. Patent 5,670,537 claims specific methods of using amlodipine besylate to treat chronic stable angina and vasospastic angina, defined by dosage regimens.
- The patent expired on March 31, 2015, removing exclusivity for these particular treatment methods.
- Method-of-use patents played a significant role in extending the market exclusivity of amlodipine beyond the expiration of its original compound patent.
- The amlodipine patent landscape is characterized by multiple patents covering compound, formulation, and use, leading to complex generic entry strategies and litigation.
- Understanding patent expiration and scope is vital for R&D strategy, identifying new market opportunities, and for investment decisions related to pharmaceutical market dynamics and competition.
Frequently Asked Questions
1. Does Patent 5,670,537 cover the drug amlodipine itself?
No, U.S. Patent 5,670,537 does not claim the amlodipine compound. It is a method-of-use patent, claiming specific ways to administer amlodipine besylate for treating certain cardiovascular conditions. The original patent for the amlodipine compound expired earlier.
2. When did the exclusivity period for Patent 5,670,537 end?
The exclusivity period for U.S. Patent 5,670,537 ended on March 31, 2015. This date is 20 years from the patent's filing date of March 31, 1995.
3. Can generic versions of amlodipine be sold for the conditions claimed in Patent 5,670,537?
Yes, since March 31, 2015, generic versions of amlodipine can be sold for the treatment of chronic stable angina and vasospastic angina according to the dosage regimens claimed in Patent 5,670,537. The expiration of this patent removed the method-of-use exclusivity for these specific applications.
4. What is the significance of "besylate" in the patent?
"Besylate" refers to the besylate salt form of amlodipine. Patents often claim specific salt forms or formulations of active pharmaceutical ingredients, as these can affect properties like stability, solubility, and bioavailability, and can be independently patentable. Patent 5,670,537 specifically claims the use of amlodipine besylate.
5. Are there other patents that protected Norvasc (amlodipine) beyond Patent 5,670,537?
Yes, Norvasc, like most major pharmaceuticals, was protected by a portfolio of patents. This portfolio included patents on the amlodipine compound itself, various salt forms, specific formulations, manufacturing processes, and other methods of use. Patent 5,670,537 was one component of this broader intellectual property strategy.
Citations
[1] Bristol-Myers Squibb Company. (1997). U.S. Patent 5,670,537. Washington, DC: U.S. Patent and Trademark Office.
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