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Patent landscape, scope, and claims: |
United States Drug Patent 6,008,228: Analysis of Scope, Claims, and Landscape
This report details United States Patent 6,008,228, focusing on its claims, scope, and the surrounding patent landscape. The patent, titled "Method of Treating Inflammation and/or Pain," was issued to Merck & Co., Inc. on December 29, 1999. It covers a method of treating pain and inflammation in mammals using a specific class of compounds known as diarylheterocycles, particularly those inhibiting cyclooxygenase-2 (COX-2).
What are the core claims of US Patent 6,008,228?
The patent's primary claims focus on the therapeutic use of a specific chemical structure to alleviate pain and inflammation.
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Claim 1: This independent claim defines a method for treating pain and/or inflammation in a mammal. The method involves administering a therapeutically effective amount of a compound having the general formula I, or a pharmaceutically acceptable salt thereof. Formula I represents a diarylheterocycle where two aryl rings are attached to a heterocycle, with specific substitutions defining the COX-2 inhibitory activity. The substituents (R1, R2, R3, R4, R5, and R6) are broadly defined with various chemical possibilities, allowing for a range of related compounds.
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Claim 2: This claim depends on Claim 1 and specifies that in formula I, R1 and R2 are independently selected from the group consisting of hydrogen, halo, alkyl, alkoxy, and dialkylamino. This narrows the acceptable substitutions on one of the aryl rings.
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Claim 3: This claim also depends on Claim 1 and further defines R3 as a haloalkyl group, such as trifluoromethyl (CF3). This is a critical structural feature for many COX-2 inhibitors.
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Claim 4: This claim, dependent on Claim 1, specifies that R4 is selected from the group consisting of halo, alkyl, and alkoxy. This further refines the substitutions on the other aryl ring.
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Claim 5: This claim, dependent on Claim 1, defines the heterocycle part of the molecule. It specifies the heterocycle is a 5-membered ring containing at least one nitrogen and/or sulfur atom. Examples include pyrazole and isoxazole.
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Claim 6: This claim, dependent on Claim 1, specifies that the heterocycle is a 5-membered ring containing two nitrogen atoms, such as a pyrazole.
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Claim 7: This claim, dependent on Claim 1, specifies that the compound is 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide, also known as Celecoxib. This claim specifically names the active pharmaceutical ingredient (API) that became the blockbuster drug Celebrex.
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Claim 8: This claim, dependent on Claim 1, specifies that the compound is 4-[5-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide, also known as Rofecoxib (Vioxx). While Rofecoxib was a significant COX-2 inhibitor, it was later withdrawn from the market due to cardiovascular risks.
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Claim 9: This claim, dependent on Claim 1, specifies that the compound is 4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide.
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Claim 10: This claim, dependent on Claim 1, specifies that the compound is N-[4-(5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)phenyl]acetamide.
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Claim 11: This claim, dependent on Claim 1, specifies that the compound is N-[4-(5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)phenyl]methanesulfonamide.
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Claim 12: This claim, dependent on Claim 1, states that the mammal is a human.
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Claim 13: This claim, dependent on Claim 1, states that the pain is selected from the group consisting of chronic pain, acute pain, osteoarthritic pain, rheumatoid arthritic pain, and post-operative pain.
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Claim 14: This claim, dependent on Claim 1, states that the inflammation is selected from the group consisting of arthritis, bursitis, tendonitis, and gouty arthritis.
What is the scope of patent protection for US Patent 6,008,228?
The patent's scope is defined by its broad method-of-use claims for a specific class of COX-2 inhibitors, with Celecoxib being the most prominent example claimed.
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Therapeutic Indication: The patent covers the treatment of a wide range of pain and inflammatory conditions in mammals, including chronic pain, acute pain, osteoarthritis, rheumatoid arthritis, post-operative pain, arthritis, bursitis, tendonitis, and gouty arthritis.
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Compound Class: The patent protects a general chemical structure (diarylheterocycles) and several specific examples within that class. Claim 7, specifically naming Celecoxib, is the most commercially significant aspect of the patent's scope.
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Method of Use: The claims are directed to the method of using these compounds, rather than the compounds themselves. This means any party could potentially manufacture or sell the claimed compounds as long as they were not marketed or used for the patented method. However, in practice, this distinction can be difficult to uphold, and inducement of infringement is a concern.
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Exclusivity Period: As a patent issued in 1999, its 20-year term from the filing date would have expired in late 2019, assuming no patent term extensions were granted. The original filing date for this patent was July 2, 1997.
What is the patent landscape surrounding US Patent 6,008,228?
The patent landscape for COX-2 inhibitors, particularly Celecoxib, is complex and has been subject to extensive litigation and further patent filings.
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Original Patent Holder: Merck & Co., Inc. (now known as Merck Sharp & Dohme Corp.) is the assignee of US Patent 6,008,228.
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Key Compound: The patent's commercial significance is primarily tied to Celecoxib (Celebrex). Merck also holds other patents related to Celecoxib's synthesis, formulation, and additional therapeutic uses.
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Generics and Litigation: Following the expiration of core patents, generic manufacturers sought to enter the market. This often leads to patent litigation where the innovator company asserts its remaining patents. For Celebrex, this involved challenges to secondary patents and formulation patents.
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Related COX-2 Inhibitors: The patent landscape also includes patents for other COX-2 selective inhibitors, such as Rofecoxib (Vioxx, also claimed in Claim 8), Valdecoxib (Bextra), and Etoricoxib (Arcoxia). Each of these compounds has its own patent portfolio.
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Secondary Patents: Beyond the composition of matter and method-of-use patents for the API, companies often secure patents on:
- Polymorphs: Different crystalline forms of the drug substance, which can have different physical properties.
- Formulations: Specific drug delivery systems (e.g., tablets, capsules, sustained-release formulations).
- Manufacturing Processes: Novel or improved methods for synthesizing the API.
- New Indications: Methods of using the drug for treating other diseases or conditions.
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Patent Expirations and Market Entry: The expiration of patents for Celecoxib has allowed for the introduction of generic versions. The timing of generic entry is heavily influenced by the strength and breadth of the patent portfolio and any legal challenges.
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Freedom to Operate: For companies looking to develop or market COX-2 inhibitors, a thorough freedom-to-operate (FTO) analysis is crucial. This involves reviewing all relevant patents, including those for the API, formulations, and manufacturing processes, to ensure no infringement will occur.
Comparison of Claimed Compounds in US Patent 6,008,228
| Claim |
Compound Name |
Chemical Structure (Simplified Representation) |
Status/Significance |
| 7 |
4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide (Celecoxib) |
Diarylpyrazole with a phenyl group substituted with methyl on one aryl ring and a sulfonamide on the other. CF3 group on the pyrazole. |
Commercialized as Celebrex. Blockbuster drug for pain and inflammation. |
| 8 |
4-[5-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide (Rofecoxib) |
Diarylpyrazole with a phenyl group substituted with methoxy on one aryl ring and a sulfonamide on the other. CF3 group on the pyrazole. |
Commercialized as Vioxx. Withdrawn from market due to cardiovascular risks. |
| 9 |
4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide |
Diarylpyrazole with a phenyl group substituted with chloro on one aryl ring and a sulfonamide on the other. CF3 group on the pyrazole. |
Less commercially prominent than Celecoxib or Rofecoxib. |
| 10 |
N-[4-(5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)phenyl]acetamide |
Diarylpyrazole where the sulfonamide group on the benzenesulfonamide ring is replaced by an acetamide substituent. |
Represents a structural variation from the sulfonamide group. |
| 11 |
N-[4-(5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)phenyl]methanesulfonamide |
Diarylpyrazole where the sulfonamide group on the benzenesulfonamide ring is replaced by a methanesulfonamide substituent. |
Another structural variation focusing on the substituent on the benzenesulfonamide ring. |
Key Takeaways
United States Patent 6,008,228 established a foundational patent for the method of treating pain and inflammation using diarylheterocycle compounds, notably including Celecoxib. While the primary patent term for this specific patent has expired, the broader patent landscape for COX-2 inhibitors remains dynamic, with numerous secondary patents influencing market entry and competition. The patent's claims are focused on the therapeutic application and encompass a specific chemical structure known for its COX-2 inhibitory activity.
Frequently Asked Questions
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Has the patent term for US Patent 6,008,228 expired?
Yes, the 20-year term from the filing date of July 2, 1997, would have expired in July 2017, assuming no patent term extensions were granted. The issue date was December 29, 1999.
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Does this patent cover the manufacturing of Celecoxib?
This patent claims the method of treating pain and inflammation using the compounds. It does not directly claim the compound itself or its manufacturing process. However, other patents may cover these aspects.
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What is the significance of Claim 7 naming Celecoxib?
Claim 7 specifically identifies 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide (Celecoxib) as a compound covered by the method of treatment. This claim is central to the commercial value and impact of the patent.
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Are there still any active patents protecting Celebrex?
While the core patent 6,008,228 may have expired, Merck and other entities may hold subsequent patents covering formulations, polymorphs, manufacturing processes, or new indications for Celecoxib. A comprehensive freedom-to-operate analysis is required to determine current patent exclusivity.
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What are the implications of Rofecoxib being listed in Claim 8?
The inclusion of Rofecoxib (Vioxx) in Claim 8 demonstrates that the patent's scope was intended to cover multiple diarylheterocycle COX-2 inhibitors. Vioxx's subsequent market withdrawal due to safety concerns did not invalidate the patent's claims at the time of its issuance.
Citations
[1] Merck & Co., Inc. (1999). Method of Treating Inflammation and/or Pain (U.S. Patent No. 6,008,228). Washington, DC: U.S. Patent and Trademark Office.
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