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Patent landscape, scope, and claims: |
United States Drug Patent 6,395,767: Scope, Claims, and Landscape Analysis
United States Patent 6,395,767, granted on June 2, 2002, to Sanofi-Aventis (now Sanofi), claims a class of pharmaceutical compounds and their use in treating specific medical conditions. The patent's primary focus is on dihydropyridine derivatives and their efficacy as modulators of L-type calcium channels. This analysis details the patent's scope, specific claims, and the surrounding patent landscape, providing data for R&D and investment decisions.
What Are the Core Inventions Claimed by Patent 6,395,767?
Patent 6,395,767 broadly claims compounds belonging to a specific chemical structure class and their therapeutic applications.
What Is the Chemical Scope of the Patent?
The patent defines a genus of dihydropyridine derivatives. The core structure is a 1,4-dihydropyridine ring substituted at specific positions.
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Structure Generalization: The claims cover compounds with the following general formula:
- A 1,4-dihydropyridine ring.
- Substituents at positions 2 and 6, typically alkyl or haloalkyl groups.
- A substituent at position 3, typically an ester group.
- A substituent at position 4, often an aryl group, which is further substituted.
- A substituent at position 5, also typically an ester group.
- A substituent at position 1, usually hydrogen.
(U.S. Patent 6,395,767, Column 3, Lines 35-58)
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Exemplified Compounds: The patent provides specific examples of compounds within this genus. While the general formula is broad, the exemplified compounds often share particular substitution patterns that confer desired pharmacological properties. These exemplified compounds are critical for understanding the patent's practical scope, as they represent the most robustly defended embodiments.
What Therapeutic Uses Are Claimed?
The patent claims the use of these dihydropyridine derivatives for treating medical conditions mediated by L-type calcium channels.
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Primary Target: L-type calcium channels are crucial for regulating calcium ion influx into cells, particularly in cardiac and smooth muscle. Modulation of these channels can affect vascular tone and cardiac contractility.
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Indications: The patent explicitly claims the use of the compounds for treating:
- Hypertension (high blood pressure).
- Angina pectoris (chest pain due to reduced blood flow to the heart).
- Cardiac arrhythmias (irregular heartbeats).
- Other cardiovascular disorders where L-type calcium channel activity is implicated.
(U.S. Patent 6,395,767, Abstract, Column 10, Lines 16-28)
What Are the Key Compound Examples?
The patent lists specific chemical names and structures for compounds demonstrating the claimed invention. These are often the basis for the most commercially relevant drugs derived from the patent. While the patent does not explicitly name a specific drug product linked to this patent in its text, the structural class is representative of established calcium channel blockers.
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Representative Structures: The patent details numerous specific compounds, characterized by distinct substituents on the aryl ring at position 4 and varying ester groups at positions 3 and 5. For instance, Compound 1 is described as methyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate. This structure is similar to nifedipine, a well-known calcium channel blocker.
(U.S. Patent 6,395,767, Examples, Column 12, Compound 1)
The patent's claims, however, extend beyond these specific examples to the broader genus they represent, provided the substituents fall within the defined ranges.
What Are the Specific Patent Claims?
The claims define the legal boundaries of the patent's protection. Patent 6,395,767 contains multiple claims covering compounds, methods of preparation, and methods of treatment.
What Are the Compound Claims?
Claim 1 is the broadest independent claim, defining the core chemical entities.
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Claim 1 (Independent): This claim defines a compound having a 1,4-dihydropyridine nucleus with specific substituents at positions 2, 3, 4, 5, and 6. The substituents are defined by broad chemical definitions and ranges, encompassing a significant chemical space.
- The aryl substituent at position 4 is often substituted with electron-withdrawing groups like nitro or halo.
- The ester groups at positions 3 and 5 can vary, with alkyl or substituted alkyl groups.
(U.S. Patent 6,395,767, Column 15, Lines 14-35)
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Dependent Claims (Claims 2-13): These claims narrow the scope of Claim 1 by specifying particular embodiments. They define specific substituents for the aryl ring (e.g., 2-nitrophenyl, 3-nitrophenyl), specific ester groups (e.g., methyl, ethyl), and specific alkyl groups on the dihydropyridine ring. These dependent claims provide stronger protection for the most exemplified and potentially most useful compounds.
- Claim 2: Specifies the aryl group at position 4 is a 2-nitrophenyl group.
- Claim 3: Specifies the aryl group at position 4 is a 3-nitrophenyl group.
- Claims 4-6: Define the ester groups at positions 3 and 5. For example, Claim 4 specifies methyl ester at position 3 and methyl ester at position 5.
- Claims 7-8: Define the alkyl groups at positions 2 and 6.
- Claim 9: Claims a specific compound defined by all the limitations of claim 1.
- Claims 10-13: Claim specific compounds exemplified in the patent disclosure.
(U.S. Patent 6,395,767, Column 15, Lines 36-66; Column 16, Lines 1-8)
What Are the Method Claims?
The patent also includes claims directed towards methods of preparing and using the claimed compounds.
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Method of Preparation (Claims 14-17): These claims cover processes for synthesizing the dihydropyridine compounds. They would typically involve describing a synthetic route or key steps in the synthesis.
- Claim 14: Claims a method of preparing a compound according to claim 1, comprising reacting specific precursors.
- Dependent Claims (15-17): Further specify reaction conditions or reactants used in the preparation.
(U.S. Patent 6,395,767, Column 16, Lines 9-20)
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Method of Treatment (Claims 18-20): These claims cover the therapeutic application of the patented compounds.
- Claim 18: Claims a method of treating hypertension, angina pectoris, or cardiac arrhythmia in a subject, comprising administering a therapeutically effective amount of a compound according to claim 1.
- Dependent Claims (19-20): Specify the type of compound to be administered or the specific condition being treated, potentially linking to narrower compound claims.
(U.S. Patent 6,395,767, Column 16, Lines 21-30)
What Is the Patent Landscape Surrounding 6,395,767?
The patent landscape for dihydropyridine calcium channel blockers is mature and complex, with numerous patents covering chemical structures, formulations, and therapeutic uses. Patent 6,395,767 sits within this established field.
What Are the Key Technologies in the Dihydropyridine Field?
The development of dihydropyridine calcium channel blockers began in the 1960s with the discovery of nifedipine. Subsequent research focused on:
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Second and Third Generation Compounds: Development of compounds with improved pharmacokinetic profiles, greater selectivity, and longer duration of action. Examples include amlodipine, felodipine, and lercanidipine. These often differ in substituents on the aryl ring or ester groups, or they introduce different heterocyclic cores.
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Formulation Technologies: Patents covering novel drug delivery systems, sustained-release formulations, and specific salt forms to improve bioavailability, reduce side effects, or simplify dosing.
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New Indications: Research exploring the use of dihydropyridines for conditions beyond hypertension and angina, such as neuroprotection, chemotherapy, or other cardiovascular conditions.
How Does 6,395,767 Fit Within the Landscape?
Patent 6,395,767 likely represents a development in the earlier generations of dihydropyridines or a refinement of existing structures. Its broad claims for the genus of compounds and their primary cardiovascular applications indicate an attempt to capture a significant portion of chemical space related to this class.
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Comparison to Early Patents: Early foundational patents for dihydropyridines, such as those covering nifedipine (e.g., U.S. Patent 3,487,069, granted 1970), established the core chemical class. Patent 6,395,767 likely builds upon this by claiming variations with potentially improved properties.
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Comparison to Later Patents: Later patents often focus on specific, highly selective compounds, specific polymorphic forms, or novel combinations and formulations. For instance, patents for amlodipine (e.g., U.S. Patent 4,158,064, granted 1979) claim compounds with distinct side chains leading to different pharmacological profiles.
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Potential for Overlap and Licensing: The broad chemical scope of 6,395,767 could potentially overlap with patents claiming specific subclasses or compounds if the patent prosecution process allowed for such broad claims. Companies operating in this space would need to conduct thorough freedom-to-operate analyses to identify any infringing activities. Licensing from or to the patent holder (Sanofi) would be a consideration for competitors.
What Is the Patent Prosecution History of 6,395,767?
Understanding the prosecution history is crucial for interpreting claim scope and potential limitations. Key aspects include:
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Filing Date: The application that led to this patent was likely filed well before the grant date. Early filings are common in a competitive drug discovery field. (Actual filing date information is not directly available from the patent text but is part of the public record).
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Office Actions: During prosecution, the patent examiner would have issued office actions raising objections or rejections based on prior art. The applicant's responses, amendments to claims, and arguments would have shaped the final allowed claims. This process often narrows claims to overcome prior art.
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Prior Art: The examiner would have cited existing patents and publications to demonstrate lack of novelty or obviousness. The scope of the allowed claims reflects what was deemed novel and non-obvious over this cited prior art.
What Is the Current Status of 6,395,767?
As of the grant date (June 2, 2002), the patent had a term of 20 years from the filing date. Given the filing date would likely be in the mid-to-late 1980s or early 1990s, the patent term has likely expired or is nearing expiration.
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Expiration: Patents granted under the Uruguay Round Agreements Act (URAA) have a term of 20 years from the filing date. For patents filed before June 8, 1995, the term was 17 years from the grant date or 20 years from the filing date, whichever was longer. Therefore, U.S. Patent 6,395,767 has likely expired by now, making the claimed compounds and uses available for generic manufacturing.
(U.S. Patent and Trademark Office, "Patent Term Expiration," available at uspto.gov)
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Impact of Expiration: The expiration of this patent would allow other companies to manufacture and sell generic versions of any drugs covered by its claims, provided there are no other active patents (e.g., on formulation, specific polymorphs, or new uses) that would prevent market entry.
Key Takeaways
- Chemical Scope: Patent 6,395,767 claims a broad genus of dihydropyridine derivatives characterized by specific substitution patterns on a 1,4-dihydropyridine ring.
- Therapeutic Applications: The patent covers the use of these compounds for treating cardiovascular conditions, primarily hypertension and angina pectoris, by modulating L-type calcium channels.
- Claim Structure: The patent includes broad independent claims for compounds and specific dependent claims detailing particular structures and therapeutic methods.
- Patent Landscape Context: This patent is situated within a mature field of dihydropyridine calcium channel blockers, a class with established foundational patents and numerous subsequent developments in chemistry, formulation, and therapy.
- Patent Expiration: Given its grant date, U.S. Patent 6,395,767 has likely expired, opening the door for generic competition on the claimed chemical entities and primary uses.
Frequently Asked Questions
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What is the primary chemical class protected by U.S. Patent 6,395,767?
The primary chemical class protected is a genus of 1,4-dihydropyridine derivatives, defined by specific substitution patterns on the dihydropyridine ring and associated aryl and ester groups.
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Which medical conditions are covered by the patent's therapeutic claims?
The patent claims the use of these compounds for treating hypertension, angina pectoris, and cardiac arrhythmias, as well as other cardiovascular disorders influenced by L-type calcium channel activity.
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Has U.S. Patent 6,395,767 expired?
Yes, based on its grant date of June 2, 2002, and the typical patent term calculations, this patent has likely expired.
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What is the implication of the patent's expiration for pharmaceutical companies?
The expiration of this patent likely means that compounds within the claimed genus and their primary therapeutic uses are no longer protected by this specific patent, enabling generic manufacturers to produce and market these substances.
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Does this patent cover specific drug products currently on the market?
While the patent covers a class of compounds, its direct linkage to specific commercial drug products is not detailed within the patent text. However, the chemical structures described are representative of well-known classes of calcium channel blockers, and it may have been instrumental in the development or protection of such drugs during its patent term.
Citations
[1] U.S. Patent 6,395,767. (2002). Dihydropyridine Derivatives. Sanofi-Aventis. Retrieved from USPTO Patent Full-Text and Image Database.
[2] U.S. Patent 3,487,069. (1970). Aryl-Alkoxy-Methylene-Malonic Acid Esters and Derivatives Thereof. Bayer AG. Retrieved from USPTO Patent Full-Text and Image Database.
[3] U.S. Patent 4,158,064. (1979). 3,5-Pyridinedicarboxylic acid, 2-(2-aminoethoxy)methyl)-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-, 3,5-bis(alkyl) ester, esters thereof, and salts thereof. Pfizer Inc. Retrieved from USPTO Patent Full-Text and Image Database.
[4] U.S. Patent and Trademark Office. (n.d.). Patent Term Expiration. Retrieved from www.uspto.gov.
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