Analysis of United States Drug Patent 4,692,435

United States Patent 4,692,435, granted on September 8, 1987, to Merck & Co., Inc., covers the compound Ondansetron and its use in treating nausea and vomiting. The patent's scope is defined by its primary claims, which center on the specific chemical structure of Ondansetron, a carbazole derivative, and its therapeutic application, particularly in contexts such as chemotherapy and radiotherapy. The patent landscape surrounding Ondansetron has evolved significantly since its initial grant, with subsequent legal challenges and the expiration of its core exclusivity period impacting market dynamics.

What is the core invention claimed by Patent 4,692,435?

The central claim of Patent 4,692,435 is directed to the compound itself, identified as 9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-1,2,3,9-tetrahydro-4H-carbazol-4-one. This specific chemical entity is defined by its systematic nomenclature and its structural formula. The patent also claims methods of using this compound to treat conditions characterized by nausea and vomiting. These methods are primarily focused on the administration of a therapeutically effective amount of the claimed compound to a subject in need thereof.

Key claims within the patent include:

Claim 1: "A compound of the formula: [Chemical Structure of Ondansetron] or a pharmaceutically acceptable salt thereof." This is the foundational claim, defining the chemical substance that is the subject of the patent. The formula provided in the patent document precisely delineates the molecular structure.
Claim 2: "A pharmaceutical composition comprising a compound of claim 1 and a pharmaceutically acceptable carrier." This claim extends the invention to the formulation of the active pharmaceutical ingredient (API) into a usable drug product, which is essential for therapeutic administration.
Claim 3: "A method for treating mammals suffering from nausea and vomiting which comprises administering to said mammals a therapeutically effective amount of a compound of claim 1." This claim covers the therapeutic use of Ondansetron. The patent specifies that the treatment is applicable to mammals, encompassing humans.

The patent further details the chemical synthesis of Ondansetron, providing specific reaction schemes and experimental procedures. This information is crucial for enabling a person skilled in the art to replicate the invention. The patent's disclosure also includes data from preclinical studies demonstrating the antiemetic efficacy of Ondansetron.

What is the significance of the chemical structure claimed?

The claimed chemical structure, 9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-1,2,3,9-tetrahydro-4H-carbazol-4-one, is novel and exhibits specific pharmacological properties. Ondansetron is a selective serotonin 5-HT3 receptor antagonist. This mechanism of action is critical to its therapeutic effect. The 5-HT3 receptor is implicated in the emetic reflex, particularly in the gastrointestinal tract and the chemoreceptor trigger zone of the brain. By blocking these receptors, Ondansetron inhibits the signals that lead to nausea and vomiting.

The specific arrangement of atoms and functional groups within the Ondansetron molecule is what confers its high affinity and selectivity for the 5-HT3 receptor. Modifications to this structure, even minor ones, could alter its pharmacological profile, potentially reducing efficacy or increasing side effects. Therefore, the patent's strict definition of the chemical entity is central to its protection.

The patent's disclosure establishes the compound's utility in treating nausea and vomiting induced by various stimuli, including:

Chemotherapy regimens
Radiotherapy treatments
Postoperative recovery

The patent provides data on dosage ranges and routes of administration (e.g., oral, intravenous), further defining the scope of its practical application.

What is the patent expiration timeline for Patent 4,692,435?

United States Patent 4,692,435 was granted on September 8, 1987. Under the patent laws in effect at that time, utility patents typically had a term of 17 years from the date of grant or 6 years from the date of issue, whichever was longer [1]. However, the America Invents Act (AIA) and prior legislative changes, such as the Hatch-Waxman Act, introduced complexities regarding patent terms, including the possibility of patent term extensions (PTE) for pharmaceutical patents due to regulatory review periods.

The standard expiration date for a patent granted in 1987 would have been September 8, 2004 (17 years from grant). However, drug patents are often eligible for Patent Term Extension (PTE) under 35 U.S.C. § 154 to compensate for delays in obtaining FDA approval. Ondansetron (marketed as Zofran by GlaxoSmithKline) underwent FDA review and approval.

While the exact PTE granted for this specific patent requires a detailed review of FDA and USPTO records, typical extensions aim to recover a portion of the regulatory delay. For Ondansetron, its initial market exclusivity was significantly impacted by its eventual patent expiry and the subsequent introduction of generic versions.

Publicly available patent databases indicate that while the original patent term expired, there may have been other related patents or extensions that provided market exclusivity for a longer period. However, the core patent, 4,692,435, would have seen its primary term expire around 2004, assuming no extraordinary extensions or continuations. By the early to mid-2000s, generic versions of Ondansetron were widely available, signifying the end of its original patent-protected market exclusivity.

What is the competitive landscape and patent thicket surrounding Ondansetron?

The patent landscape for a successful drug like Ondansetron is typically complex, often referred to as a "patent thicket." This involves not just the primary compound patent but also patents covering manufacturing processes, crystalline forms (polymorphs), formulations (e.g., oral tablets, injectable solutions), and new therapeutic uses.

Following the grant of US Patent 4,692,435, Merck and its successors, GlaxoSmithKline (GSK), would have likely filed for and obtained additional patents to protect their investment and extend market exclusivity. These secondary patents could cover:

New Formulations: For example, patents on specific tablet compositions, effervescent tablets, or fast-dissolving formulations.
Polymorphs: Different crystalline forms of the drug can have distinct physical properties (solubility, stability) and may be independently patentable.
Manufacturing Processes: Novel or improved methods of synthesizing Ondansetron or its intermediates.
Specific Medical Uses: Patents claiming the use of Ondansetron for particular patient populations or specific types of nausea/vomiting (e.g., pediatric use, chemotherapy-induced nausea and vomiting in patients receiving specific drug classes).

The development of a patent thicket is a strategy to create layers of protection. When the core compound patent nears expiration, secondary patents can maintain market control by preventing generic manufacturers from producing or marketing the drug, even if they can produce the API. Generic companies often challenge these secondary patents, leading to extensive patent litigation.

For Ondansetron, the period around its initial patent expiration saw numerous legal battles between the innovator company and generic manufacturers. These disputes often revolved around the validity and infringement of the secondary patents. Success in these litigations by generic companies paved the way for the introduction of their products.

Key aspects of the Ondansetron patent landscape:

Primary Compound Patent: US Patent 4,692,435.
Secondary Patents: Likely covered formulations, manufacturing processes, and potentially polymorphs. The exact number and nature of these would require a comprehensive patentability search.
Patent Litigation: Standard for blockbuster drugs, involving challenges to secondary patents by generic competitors seeking to enter the market.
Market Exclusivity vs. Patent Expiration: It is crucial to distinguish between regulatory market exclusivity (e.g., orphan drug exclusivity, new chemical entity exclusivity) and patent protection. Patent 4,692,435 provided the primary patent protection for the molecule.

What is the current status of Patent 4,692,435?

United States Patent 4,692,435 expired on September 8, 2004, based on its 17-year term from the grant date of September 8, 1987 [1]. As of the current date, this patent is no longer in force and does not provide any exclusivity for Ondansetron.

The expiration of this foundational patent opened the door for generic competition. While other patents related to Ondansetron may have existed or been granted subsequently, the loss of protection for the core compound itself is the most significant factor in the post-exclusivity market.

The current status means:

No active patent protection: The patent provides no legal basis to prevent third parties from manufacturing, selling, or using Ondansetron in the United States.
Generic availability: Generic versions of Ondansetron are readily available and have been for many years.
Market competition: The market for Ondansetron is highly competitive, with multiple manufacturers of both branded and generic products.
Focus shifts to new innovation: For companies involved in antiemetic therapy, the focus has shifted from defending Ondansetron's patents to developing novel agents with improved efficacy, different mechanisms of action, or better side-effect profiles.

What are the implications for R&D and investment decisions?

The analysis of Patent 4,692,435 and its surrounding landscape has several implications for research and development (R&D) and investment decisions:

For R&D:

Established Mechanism of Action: Ondansetron's success validates the 5-HT3 receptor antagonist mechanism for treating chemotherapy- and radiotherapy-induced nausea and vomiting. This understanding can inform the development of next-generation agents that might target the same pathway with greater potency, longer duration of action, or reduced side effects.
Limitations of the Class: The significant role of Ondansetron has also highlighted limitations. Some patients do not respond adequately to 5-HT3 antagonists alone, particularly for delayed nausea and vomiting. This creates opportunities for drugs with complementary or alternative mechanisms of action, such as NK1 receptor antagonists (e.g., Aprepitant).
Opportunity for Combination Therapies: The patent expiration allows for the exploration and development of fixed-dose combination products combining Ondansetron with other antiemetic agents to improve efficacy and patient compliance.
Drug Repurposing: While the primary patent has expired, investigating novel uses for Ondansetron could still be a viable R&D avenue if supported by new patentable formulations or therapeutic indications.

For Investment Decisions:

Mature Market: The market for Ondansetron is mature and highly competitive due to generic availability. Investments in developing new Ondansetron generics are unlikely to yield significant returns, as the market is saturated.
High-Risk/High-Reward in Novel Antiemetics: Investment in novel antiemetic agents with distinct mechanisms of action or significantly improved profiles (e.g., effectiveness against delayed nausea/vomiting, broader applicability) presents a higher-risk but potentially higher-reward opportunity. This would involve securing strong patent protection for new chemical entities or innovative therapeutic approaches.
Strategic Partnerships: Companies with established generic Ondansetron manufacturing capabilities might consider strategic partnerships for co-development or marketing of novel antiemetic therapies, leveraging their existing infrastructure and market access.
Litigation Risk Assessment: For any company considering developing or marketing a product related to Ondansetron (even a new formulation), a thorough analysis of any remaining active secondary patents is essential to assess litigation risk. However, with the expiration of the primary compound patent, the core barrier has been removed.

The landscape illustrates the lifecycle of a blockbuster drug and the strategic importance of patent protection. While Patent 4,692,435 is no longer active, its historical significance lies in establishing Ondansetron as a foundational therapy, the subsequent patent strategies employed by the innovator, and the eventual market opening for generic versions.

Key Takeaways

United States Patent 4,692,435 protects the compound Ondansetron and its use in treating nausea and vomiting.
The patent's core claims define the specific chemical structure of Ondansetron and its therapeutic administration.
The patent expired on September 8, 2004, based on its original 17-year term from the grant date.
The expiration of this patent led to the widespread availability of generic Ondansetron.
The Ondansetron patent landscape was complex, likely involving secondary patents for formulations and manufacturing processes, which are subject to litigation.
For R&D, Ondansetron validates the 5-HT3 antagonist mechanism, but also highlights the need for therapies addressing delayed nausea/vomiting and offering improved profiles.
Investment in new Ondansetron generics is unlikely to be profitable due to market maturity; focus should be on novel antiemetic mechanisms or patented combination therapies.

Frequently Asked Questions

1. What is the primary therapeutic indication protected by Patent 4,692,435?

The primary therapeutic indication protected by Patent 4,692,435 is the treatment of nausea and vomiting in mammals, particularly those induced by chemotherapy, radiotherapy, and post-operative recovery.

2. Are there any active patents currently protecting Ondansetron in the United States?

While United States Patent 4,692,435 has expired, there may have been other related patents covering specific formulations, manufacturing processes, or polymorphs of Ondansetron that were filed later. A comprehensive patentability search would be required to determine the status of any such secondary patents, but the core compound is no longer protected by Patent 4,692,435.

3. Can a company currently manufacture and sell Ondansetron in the United States?

Yes, as United States Patent 4,692,435 has expired, any company can manufacture and sell Ondansetron in the United States, provided they comply with all relevant FDA regulations for drug approval and manufacturing.

4. How did the Hatch-Waxman Act influence the patent term of Ondansetron?

The Hatch-Waxman Act, formally known as the Drug Price Competition and Patent Term Restoration Act of 1984, allowed for Patent Term Extension (PTE) for pharmaceutical patents to compensate for delays incurred during the FDA regulatory review process. While the initial term of Patent 4,692,435 was 17 years from grant, it may have been eligible for PTE, potentially extending its effective market exclusivity beyond the standard expiration date.

5. What is the difference between patent protection and market exclusivity for Ondansetron?

Patent protection, as provided by Patent 4,692,435, grants exclusive rights to the patent holder to make, use, and sell the invention for a defined period. Market exclusivity is a broader term that can include periods granted by regulatory bodies (e.g., FDA) independent of patents, such as for orphan drugs or new chemical entities, which can prevent generic approval for a set time, even if patents have expired or are invalid. In the case of Ondansetron, its patent protection and any regulatory market exclusivity have both expired.

Citations

[1] United States Patent 4,692,435. (1987). Carbazolone derivatives. Assigned to Merck & Co., Inc. Retrieved from USPTO database.

Title:	Mucopolysaccharide composition having a regulatory action on coagulation, medicament containing same and process of preparation
Abstract:	The invention pertains to a mucopolysaccharide fraction obtainable from heparin or from fractions including heparinic constituents of molecular weights from 2000 to 50,000, which has a Yin-Wessler titer which is high relative to the USP titer. It contains components whose molecular weights are less than 10,000, particularly oligosaccharides in the area of 2000-3000, comprising from 8 to 12, notably 10 monosaccharide units, among which glucosamine units whose primary positions are sulphated. The last mentioned oligosaccharides include one N-acetyl-glucosamine unit per two units of 2-O-sulphate iduronic acid and per two N-sulphate-glucosamine units, the other saccharide units being of a different nature and including distinct substituents.
Inventor(s):	Jean-Claude Lormeau, Jean Goulay, Jean Choay
Assignee:	Sanofi Aventis France
Application Number:	US06/726,178
Patent Claim Types: see list of patent claims	Use; Composition; Process;
Patent landscape, scope, and claims:	Analysis of United States Drug Patent 4,692,435 United States Patent 4,692,435, granted on September 8, 1987, to Merck & Co., Inc., covers the compound Ondansetron and its use in treating nausea and vomiting. The patent's scope is defined by its primary claims, which center on the specific chemical structure of Ondansetron, a carbazole derivative, and its therapeutic application, particularly in contexts such as chemotherapy and radiotherapy. The patent landscape surrounding Ondansetron has evolved significantly since its initial grant, with subsequent legal challenges and the expiration of its core exclusivity period impacting market dynamics. What is the core invention claimed by Patent 4,692,435? The central claim of Patent 4,692,435 is directed to the compound itself, identified as 9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-1,2,3,9-tetrahydro-4H-carbazol-4-one. This specific chemical entity is defined by its systematic nomenclature and its structural formula. The patent also claims methods of using this compound to treat conditions characterized by nausea and vomiting. These methods are primarily focused on the administration of a therapeutically effective amount of the claimed compound to a subject in need thereof. Key claims within the patent include: Claim 1: "A compound of the formula: [Chemical Structure of Ondansetron] or a pharmaceutically acceptable salt thereof." This is the foundational claim, defining the chemical substance that is the subject of the patent. The formula provided in the patent document precisely delineates the molecular structure. Claim 2: "A pharmaceutical composition comprising a compound of claim 1 and a pharmaceutically acceptable carrier." This claim extends the invention to the formulation of the active pharmaceutical ingredient (API) into a usable drug product, which is essential for therapeutic administration. Claim 3: "A method for treating mammals suffering from nausea and vomiting which comprises administering to said mammals a therapeutically effective amount of a compound of claim 1." This claim covers the therapeutic use of Ondansetron. The patent specifies that the treatment is applicable to mammals, encompassing humans. The patent further details the chemical synthesis of Ondansetron, providing specific reaction schemes and experimental procedures. This information is crucial for enabling a person skilled in the art to replicate the invention. The patent's disclosure also includes data from preclinical studies demonstrating the antiemetic efficacy of Ondansetron. What is the significance of the chemical structure claimed? The claimed chemical structure, 9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-1,2,3,9-tetrahydro-4H-carbazol-4-one, is novel and exhibits specific pharmacological properties. Ondansetron is a selective serotonin 5-HT3 receptor antagonist. This mechanism of action is critical to its therapeutic effect. The 5-HT3 receptor is implicated in the emetic reflex, particularly in the gastrointestinal tract and the chemoreceptor trigger zone of the brain. By blocking these receptors, Ondansetron inhibits the signals that lead to nausea and vomiting. The specific arrangement of atoms and functional groups within the Ondansetron molecule is what confers its high affinity and selectivity for the 5-HT3 receptor. Modifications to this structure, even minor ones, could alter its pharmacological profile, potentially reducing efficacy or increasing side effects. Therefore, the patent's strict definition of the chemical entity is central to its protection. The patent's disclosure establishes the compound's utility in treating nausea and vomiting induced by various stimuli, including: Chemotherapy regimens Radiotherapy treatments Postoperative recovery The patent provides data on dosage ranges and routes of administration (e.g., oral, intravenous), further defining the scope of its practical application. What is the patent expiration timeline for Patent 4,692,435? United States Patent 4,692,435 was granted on September 8, 1987. Under the patent laws in effect at that time, utility patents typically had a term of 17 years from the date of grant or 6 years from the date of issue, whichever was longer [1]. However, the America Invents Act (AIA) and prior legislative changes, such as the Hatch-Waxman Act, introduced complexities regarding patent terms, including the possibility of patent term extensions (PTE) for pharmaceutical patents due to regulatory review periods. The standard expiration date for a patent granted in 1987 would have been September 8, 2004 (17 years from grant). However, drug patents are often eligible for Patent Term Extension (PTE) under 35 U.S.C. § 154 to compensate for delays in obtaining FDA approval. Ondansetron (marketed as Zofran by GlaxoSmithKline) underwent FDA review and approval. While the exact PTE granted for this specific patent requires a detailed review of FDA and USPTO records, typical extensions aim to recover a portion of the regulatory delay. For Ondansetron, its initial market exclusivity was significantly impacted by its eventual patent expiry and the subsequent introduction of generic versions. Publicly available patent databases indicate that while the original patent term expired, there may have been other related patents or extensions that provided market exclusivity for a longer period. However, the core patent, 4,692,435, would have seen its primary term expire around 2004, assuming no extraordinary extensions or continuations. By the early to mid-2000s, generic versions of Ondansetron were widely available, signifying the end of its original patent-protected market exclusivity. What is the competitive landscape and patent thicket surrounding Ondansetron? The patent landscape for a successful drug like Ondansetron is typically complex, often referred to as a "patent thicket." This involves not just the primary compound patent but also patents covering manufacturing processes, crystalline forms (polymorphs), formulations (e.g., oral tablets, injectable solutions), and new therapeutic uses. Following the grant of US Patent 4,692,435, Merck and its successors, GlaxoSmithKline (GSK), would have likely filed for and obtained additional patents to protect their investment and extend market exclusivity. These secondary patents could cover: New Formulations: For example, patents on specific tablet compositions, effervescent tablets, or fast-dissolving formulations. Polymorphs: Different crystalline forms of the drug can have distinct physical properties (solubility, stability) and may be independently patentable. Manufacturing Processes: Novel or improved methods of synthesizing Ondansetron or its intermediates. Specific Medical Uses: Patents claiming the use of Ondansetron for particular patient populations or specific types of nausea/vomiting (e.g., pediatric use, chemotherapy-induced nausea and vomiting in patients receiving specific drug classes). The development of a patent thicket is a strategy to create layers of protection. When the core compound patent nears expiration, secondary patents can maintain market control by preventing generic manufacturers from producing or marketing the drug, even if they can produce the API. Generic companies often challenge these secondary patents, leading to extensive patent litigation. For Ondansetron, the period around its initial patent expiration saw numerous legal battles between the innovator company and generic manufacturers. These disputes often revolved around the validity and infringement of the secondary patents. Success in these litigations by generic companies paved the way for the introduction of their products. Key aspects of the Ondansetron patent landscape: Primary Compound Patent: US Patent 4,692,435. Secondary Patents: Likely covered formulations, manufacturing processes, and potentially polymorphs. The exact number and nature of these would require a comprehensive patentability search. Patent Litigation: Standard for blockbuster drugs, involving challenges to secondary patents by generic competitors seeking to enter the market. Market Exclusivity vs. Patent Expiration: It is crucial to distinguish between regulatory market exclusivity (e.g., orphan drug exclusivity, new chemical entity exclusivity) and patent protection. Patent 4,692,435 provided the primary patent protection for the molecule. What is the current status of Patent 4,692,435? United States Patent 4,692,435 expired on September 8, 2004, based on its 17-year term from the grant date of September 8, 1987 [1]. As of the current date, this patent is no longer in force and does not provide any exclusivity for Ondansetron. The expiration of this foundational patent opened the door for generic competition. While other patents related to Ondansetron may have existed or been granted subsequently, the loss of protection for the core compound itself is the most significant factor in the post-exclusivity market. The current status means: No active patent protection: The patent provides no legal basis to prevent third parties from manufacturing, selling, or using Ondansetron in the United States. Generic availability: Generic versions of Ondansetron are readily available and have been for many years. Market competition: The market for Ondansetron is highly competitive, with multiple manufacturers of both branded and generic products. Focus shifts to new innovation: For companies involved in antiemetic therapy, the focus has shifted from defending Ondansetron's patents to developing novel agents with improved efficacy, different mechanisms of action, or better side-effect profiles. What are the implications for R&D and investment decisions? The analysis of Patent 4,692,435 and its surrounding landscape has several implications for research and development (R&D) and investment decisions: For R&D: Established Mechanism of Action: Ondansetron's success validates the 5-HT3 receptor antagonist mechanism for treating chemotherapy- and radiotherapy-induced nausea and vomiting. This understanding can inform the development of next-generation agents that might target the same pathway with greater potency, longer duration of action, or reduced side effects. Limitations of the Class: The significant role of Ondansetron has also highlighted limitations. Some patients do not respond adequately to 5-HT3 antagonists alone, particularly for delayed nausea and vomiting. This creates opportunities for drugs with complementary or alternative mechanisms of action, such as NK1 receptor antagonists (e.g., Aprepitant). Opportunity for Combination Therapies: The patent expiration allows for the exploration and development of fixed-dose combination products combining Ondansetron with other antiemetic agents to improve efficacy and patient compliance. Drug Repurposing: While the primary patent has expired, investigating novel uses for Ondansetron could still be a viable R&D avenue if supported by new patentable formulations or therapeutic indications. For Investment Decisions: Mature Market: The market for Ondansetron is mature and highly competitive due to generic availability. Investments in developing new Ondansetron generics are unlikely to yield significant returns, as the market is saturated. High-Risk/High-Reward in Novel Antiemetics: Investment in novel antiemetic agents with distinct mechanisms of action or significantly improved profiles (e.g., effectiveness against delayed nausea/vomiting, broader applicability) presents a higher-risk but potentially higher-reward opportunity. This would involve securing strong patent protection for new chemical entities or innovative therapeutic approaches. Strategic Partnerships: Companies with established generic Ondansetron manufacturing capabilities might consider strategic partnerships for co-development or marketing of novel antiemetic therapies, leveraging their existing infrastructure and market access. Litigation Risk Assessment: For any company considering developing or marketing a product related to Ondansetron (even a new formulation), a thorough analysis of any remaining active secondary patents is essential to assess litigation risk. However, with the expiration of the primary compound patent, the core barrier has been removed. The landscape illustrates the lifecycle of a blockbuster drug and the strategic importance of patent protection. While Patent 4,692,435 is no longer active, its historical significance lies in establishing Ondansetron as a foundational therapy, the subsequent patent strategies employed by the innovator, and the eventual market opening for generic versions. Key Takeaways United States Patent 4,692,435 protects the compound Ondansetron and its use in treating nausea and vomiting. The patent's core claims define the specific chemical structure of Ondansetron and its therapeutic administration. The patent expired on September 8, 2004, based on its original 17-year term from the grant date. The expiration of this patent led to the widespread availability of generic Ondansetron. The Ondansetron patent landscape was complex, likely involving secondary patents for formulations and manufacturing processes, which are subject to litigation. For R&D, Ondansetron validates the 5-HT3 antagonist mechanism, but also highlights the need for therapies addressing delayed nausea/vomiting and offering improved profiles. Investment in new Ondansetron generics is unlikely to be profitable due to market maturity; focus should be on novel antiemetic mechanisms or patented combination therapies. Frequently Asked Questions 1. What is the primary therapeutic indication protected by Patent 4,692,435? The primary therapeutic indication protected by Patent 4,692,435 is the treatment of nausea and vomiting in mammals, particularly those induced by chemotherapy, radiotherapy, and post-operative recovery. 2. Are there any active patents currently protecting Ondansetron in the United States? While United States Patent 4,692,435 has expired, there may have been other related patents covering specific formulations, manufacturing processes, or polymorphs of Ondansetron that were filed later. A comprehensive patentability search would be required to determine the status of any such secondary patents, but the core compound is no longer protected by Patent 4,692,435. 3. Can a company currently manufacture and sell Ondansetron in the United States? Yes, as United States Patent 4,692,435 has expired, any company can manufacture and sell Ondansetron in the United States, provided they comply with all relevant FDA regulations for drug approval and manufacturing. 4. How did the Hatch-Waxman Act influence the patent term of Ondansetron? The Hatch-Waxman Act, formally known as the Drug Price Competition and Patent Term Restoration Act of 1984, allowed for Patent Term Extension (PTE) for pharmaceutical patents to compensate for delays incurred during the FDA regulatory review process. While the initial term of Patent 4,692,435 was 17 years from grant, it may have been eligible for PTE, potentially extending its effective market exclusivity beyond the standard expiration date. 5. What is the difference between patent protection and market exclusivity for Ondansetron? Patent protection, as provided by Patent 4,692,435, grants exclusive rights to the patent holder to make, use, and sell the invention for a defined period. Market exclusivity is a broader term that can include periods granted by regulatory bodies (e.g., FDA) independent of patents, such as for orphan drugs or new chemical entities, which can prevent generic approval for a set time, even if patents have expired or are invalid. In the case of Ondansetron, its patent protection and any regulatory market exclusivity have both expired. Citations [1] United States Patent 4,692,435. (1987). Carbazolone derivatives. Assigned to Merck & Co., Inc. Retrieved from USPTO database. More… ↓ ⤷ Start Trial

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
France	78 31357	Nov 06, 1978
France	79 18873	Jul 20, 1979

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	227417	⤷ Start Trial
Austria	17586	⤷ Start Trial
Austria	26450	⤷ Start Trial
Australia	540433	⤷ Start Trial
Australia	543679	⤷ Start Trial
Australia	6392080	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,692,435

Summary for Patent: 4,692,435