Analysis of United States Patent 6,319,913 for Zolpidem Tartrate

This analysis examines United States Patent 6,319,913, which covers crystalline forms of zolpidem tartrate. The patent, granted to Sanofi-Synthelabo, details specific polymorphic forms of the active pharmaceutical ingredient (API) found in Ambien. Understanding the scope and claims of this patent is crucial for assessing market exclusivity, potential for generic competition, and the breadth of intellectual property protection surrounding zolpidem tartrate.

What is the Core Innovation Protected by Patent 6,319,913?

Patent 6,319,913 protects specific crystalline forms of zolpidem tartrate. Zolpidem tartrate is the active pharmaceutical ingredient in Ambien, a widely prescribed hypnotic medication. The patent focuses on the solid-state chemistry of the drug, specifically identifying and claiming distinct crystalline polymorphic forms that offer advantages over previously known forms. Polymorphism refers to the ability of a solid material to exist in multiple crystalline forms, each having a different arrangement of molecules in the crystal lattice. These different forms can exhibit variations in physical properties such as solubility, dissolution rate, stability, and bioavailability, which are critical for drug formulation and therapeutic efficacy.

The patent claims at least three specific crystalline forms of zolpidem tartrate, identified as Form A, Form B, and Form C. These forms are characterized by their unique X-ray powder diffraction (XRPD) patterns, infrared (IR) spectroscopy data, and differential scanning calorimetry (DSC) profiles.

Form A: Described as a stable crystalline form of zolpidem tartrate. Its XRPD pattern exhibits characteristic peaks at specific 2-theta angles.
Form B: Identified as another stable crystalline form. It is differentiated from Form A by its distinct XRPD pattern.
Form C: Also claimed as a stable crystalline form, with its own unique XRPD signature.

The specification suggests that these crystalline forms were developed to provide improved stability and/or manufacturing advantages compared to amorphous or other crystalline forms of zolpidem tartrate. By securing patent protection for these specific solid-state forms, Sanofi-Synthelabo aimed to extend market exclusivity for its zolpidem tartrate products beyond the expiration of earlier patents covering the compound itself or its initial pharmaceutical compositions.

What are the Key Claims within Patent 6,319,913?

United States Patent 6,319,913 contains several claims that define the boundaries of its intellectual property protection. The most significant claims relate to the specific crystalline forms of zolpidem tartrate.

Claim 1: This independent claim is central to the patent's scope. It claims a crystalline form of zolpidem tartrate that is characterized by its X-ray powder diffraction pattern having characteristic peaks at specified 2-theta angles. This claim provides a method for identifying and distinguishing this specific crystalline form based on its diffraction fingerprint.

Claim 2: This claim defines another specific crystalline form of zolpidem tartrate, also characterized by its X-ray powder diffraction pattern, with a different set of characteristic peaks. This claim protects a distinct polymorphic form.

Claim 3: This claim defines a third specific crystalline form of zolpidem tartrate, again characterized by its unique X-ray powder diffraction pattern.

Dependent Claims: The patent also includes dependent claims that further narrow the scope or describe specific aspects of the claimed crystalline forms. These might include:

Claims specifying that the crystalline form is substantially free of other polymorphic forms.
Claims that incorporate additional characterization data, such as IR spectroscopy or DSC thermograms, in conjunction with the XRPD data.
Claims for pharmaceutical compositions comprising one or more of the claimed crystalline forms of zolpidem tartrate.
Claims for methods of treating insomnia or other sleep disorders using such compositions.

The precise wording of these claims determines what activities constitute infringement. Generally, any party that manufactures, uses, sells, or imports zolpidem tartrate in one of the specifically claimed crystalline forms within the United States, without authorization from the patent holder, would be considered an infringer. The emphasis on specific crystalline forms means that generic manufacturers may be able to develop non-infringing formulations by utilizing alternative polymorphic forms, or amorphous forms, of zolpidem tartrate, provided these are not covered by other existing patents.

What is the Patent Landscape for Zolpidem Tartrate and its Polymorphs?

The patent landscape for zolpidem tartrate is complex, reflecting its long history as a commercially successful drug. United States Patent 6,319,913 is a key component of this landscape, specifically addressing the solid-state forms of the API.

Early Patents: The initial patents covering zolpidem itself and its basic pharmaceutical compositions were filed and granted much earlier. For instance, the foundational patent for zolpidem was held by Synthelabo (now part of Sanofi). These early patents established the existence and therapeutic utility of the compound.

Polymorph Patents: United States Patent 6,319,913, filed on November 5, 1999, and granted on October 2, 2001, is an example of a "polymorph patent." These patents are often filed later in a drug's lifecycle to provide extended protection for specific solid-state forms of an existing API. The rationale is that while the compound itself may be off-patent or close to expiring, a novel and advantageous crystalline form can be considered a new invention.

Key Patent Expirations:

The primary patents covering zolpidem tartrate have long since expired. For example, the original composition of matter patents would have expired in the early to mid-2000s.
The expiration of United States Patent 6,319,913, which has a term extending 20 years from its filing date (November 5, 1999), means its protection ended on November 5, 2019. This date is significant as it marks the point after which the specific crystalline forms claimed in this patent are no longer protected by this particular patent.

Impact on Generic Competition: The expiration of United States Patent 6,319,913, along with the expiration of earlier foundational patents, has facilitated the entry of generic versions of zolpidem tartrate into the market. Generic manufacturers can now produce and market zolpidem tartrate without infringing on the intellectual property rights previously held by Sanofi-Synthelabo. However, it is crucial for generic companies to ensure that their chosen crystalline form of zolpidem tartrate does not infringe on any currently active patents, which might cover other polymorphs, specific formulations, or manufacturing processes.

Other Related Intellectual Property: The patent landscape may also include patents related to:

Other Polymorphs: It is possible that other polymorphic forms of zolpidem tartrate exist or have been patented by Sanofi or other entities, which may have different expiration dates.
Formulations: Patents may exist for specific drug delivery systems or formulations of zolpidem tartrate, such as extended-release versions (e.g., Ambien CR), which may have their own patent protection and expiration timelines.
Manufacturing Processes: Novel and inventive methods for synthesizing or crystallizing zolpidem tartrate could also be patented.
Combinations: Patents might cover combinations of zolpidem tartrate with other active ingredients.

Therefore, while United States Patent 6,319,913 has expired, a comprehensive freedom-to-operate analysis would necessitate a review of all other relevant patents for zolpidem tartrate and its formulations that may still be in force.

What are the Commercial Implications of Patent 6,319,913's Claims and Expiration?

The commercial implications of United States Patent 6,319,913 are primarily linked to its role in extending market exclusivity and its subsequent expiration facilitating generic market entry.

Market Exclusivity Extension: When granted, United States Patent 6,319,913 provided Sanofi-Synthelabo with a period of extended market exclusivity for zolpidem tartrate in specific crystalline forms. This allowed the company to maintain a competitive advantage and command premium pricing for its branded zolpidem products, such as Ambien and Ambien CR, even as earlier patents expired. The protection of specific polymorphs is a common strategy in the pharmaceutical industry to extend a drug's patent life beyond the initial composition of matter and formulation patents. By identifying and patenting novel crystalline forms with desirable properties (e.g., enhanced stability, improved dissolution profiles, easier manufacturing), companies can create new intellectual property that blocks competitors from using those specific forms.

Facilitation of Generic Competition: The expiration of United States Patent 6,319,913 on November 5, 2019, removed a significant barrier to generic competition for zolpidem tartrate. Once the patent protection for these specific crystalline forms lapsed, generic pharmaceutical manufacturers were legally free to develop and market their own versions of zolpidem tartrate that utilized these previously protected forms. This has led to a substantial increase in the availability of generic zolpidem tartrate products, which are typically offered at lower prices than the branded version. The entry of generics intensifies competition, drives down prices, and increases patient access to the medication.

Impact on Pricing and Market Share: Prior to the expiration of this patent and others, Sanofi-Synthelabo held a dominant position in the zolpidem tartrate market. Following patent expirations, the market share of branded Ambien has significantly declined as generic versions have captured a substantial portion of the market. This shift is accompanied by a dramatic reduction in the average selling price of zolpidem tartrate due to price competition among multiple generic manufacturers.

R&D and Investment Considerations: For pharmaceutical companies involved in R&D or investment in the sleep disorder therapeutic area, understanding the patent expiry dates of key drugs like zolpidem tartrate is critical.

For Innovator Companies: The expiration of such patents signals the end of a revenue stream and necessitates a focus on developing new, patent-protected products to replace lost exclusivity.
For Generic Companies: Patent expiration dates are key milestones that trigger opportunities for market entry. Companies will conduct detailed freedom-to-operate analyses to identify non-infringing development paths.
For Investors: Knowledge of patent lifecycles informs investment decisions, allowing for the identification of companies poised to benefit from patent expirations or those facing revenue declines due to generic competition.

Manufacturing and Formulation Strategies: The existence of polymorph patents like 6,319,913 influences manufacturing and formulation strategies.

Pre-Expiration: Companies seeking to enter the market prior to the patent's expiration would have had to develop alternative crystalline forms or amorphous forms of zolpidem tartrate that were not covered by the patent. This could involve significant R&D investment to identify and characterize such forms and to demonstrate their bioequivalence and stability.
Post-Expiration: With the patent expired, manufacturers can now utilize the patented crystalline forms, potentially simplifying their development and manufacturing processes if those forms offer significant advantages.

In summary, Patent 6,319,913 played a role in the commercial lifecycle of zolpidem tartrate by extending its market exclusivity. Its expiration has had a profound impact on the market by opening the door for widespread generic competition, leading to price reductions and increased patient access.

What is the Status of Patent 6,319,913?

United States Patent 6,319,913 has expired. The patent was filed on November 5, 1999, and granted on October 2, 2001. Under U.S. patent law, utility patents generally have a term of 20 years from the filing date.

Therefore, the statutory term for United States Patent 6,319,913 ended on November 5, 2019. This means that the patent protection originally granted for the specific crystalline forms of zolpidem tartrate described and claimed in this patent is no longer in force.

The expiration of this patent has significant implications:

It removes the patent-based restriction on the use, sale, and manufacture of zolpidem tartrate in the crystalline forms claimed by this patent within the United States.
It allows generic pharmaceutical companies to utilize these specific crystalline forms in their own zolpidem tartrate products without infringing on this particular patent.

It is important to note that the expiration of this patent does not necessarily mean that all intellectual property protection related to zolpidem tartrate has ended. Other patents, such as those covering different polymorphic forms, specific pharmaceutical formulations (e.g., extended-release versions), or manufacturing processes, may still be in effect or may have expired at different times. However, the protection specifically afforded by Patent 6,319,913 for its claimed crystalline forms has concluded.

What are the Key Takeaways?

United States Patent 6,319,913 protected specific crystalline polymorphic forms (Forms A, B, and C) of zolpidem tartrate, the active ingredient in Ambien.
The patent's claims were based on the unique solid-state characteristics of these crystalline forms, primarily defined by X-ray powder diffraction patterns.
This patent served as a mechanism to extend market exclusivity for zolpidem tartrate beyond the expiration of earlier composition of matter patents.
The patent term for United States Patent 6,319,913 expired on November 5, 2019, 20 years from its filing date.
The expiration of this patent has enabled the widespread entry of generic zolpidem tartrate products into the U.S. market, leading to increased competition and reduced prices.
While this specific patent has expired, a comprehensive freedom-to-operate analysis for zolpidem tartrate would still require consideration of any other potentially active patents covering different polymorphs, formulations, or manufacturing processes.

Frequently Asked Questions

1. Did patent 6,319,913 cover zolpidem itself, or specific forms of it?

Patent 6,319,913 specifically covered crystalline polymorphic forms of zolpidem tartrate, not zolpidem or zolpidem tartrate in general. Earlier patents would have covered the compound itself.

2. What is the significance of "crystalline forms" in pharmaceutical patents?

Crystalline forms, or polymorphs, are different solid-state structures of the same chemical compound. They can have varying physical properties such as solubility, stability, and dissolution rate, which impact manufacturing and therapeutic efficacy. Patenting specific advantageous polymorphs allows innovators to extend market exclusivity beyond original composition of matter patents.

3. Does the expiration of patent 6,319,913 mean all zolpidem patents have expired?

No, the expiration of patent 6,319,913 means protection for the specific crystalline forms it claimed has ended. Other patents related to different zolpidem tartrate polymorphs, pharmaceutical compositions (e.g., extended-release formulations), or manufacturing processes may still be in force or have expired at different times.

4. What does it mean for a generic company if patent 6,319,913 has expired?

It means generic companies are now free to manufacture and sell zolpidem tartrate using the crystalline forms that were protected by this specific patent, provided they do not infringe on any other currently active patents.

5. Can a company be sued for patent infringement if patent 6,319,913 is expired?

A company cannot be sued for infringement of patent 6,319,913 if the alleged infringement occurred after its expiration date of November 5, 2019. However, they could still face infringement claims if their product or process violates the terms of any other currently active and relevant patents.

Citations

[1] Sanofi-Synthelabo. (2001). Crystalline Forms of Zolpidem Tartrate. U.S. Patent 6,319,913. Washington, D.C.: U.S. Patent and Trademark Office.

Title:	Penetration enhancing and irritation reducing systems
Abstract:	This invention lies in the technology of transdermal and topical drug delivery. In particular, the present invention relates to enhancement of the penetration of transdermally or topically applied drugs and with the reduction of skin irritation that often accompanies transdermal and topical drug delivery.
Inventor(s):	Vivien H. W. Mak, Stephen Grayson
Assignee:	Strakan International SA
Application Number:	US09/189,090
Patent Claim Types: see list of patent claims	Use; Composition;
Patent landscape, scope, and claims:	Analysis of United States Patent 6,319,913 for Zolpidem Tartrate This analysis examines United States Patent 6,319,913, which covers crystalline forms of zolpidem tartrate. The patent, granted to Sanofi-Synthelabo, details specific polymorphic forms of the active pharmaceutical ingredient (API) found in Ambien. Understanding the scope and claims of this patent is crucial for assessing market exclusivity, potential for generic competition, and the breadth of intellectual property protection surrounding zolpidem tartrate. What is the Core Innovation Protected by Patent 6,319,913? Patent 6,319,913 protects specific crystalline forms of zolpidem tartrate. Zolpidem tartrate is the active pharmaceutical ingredient in Ambien, a widely prescribed hypnotic medication. The patent focuses on the solid-state chemistry of the drug, specifically identifying and claiming distinct crystalline polymorphic forms that offer advantages over previously known forms. Polymorphism refers to the ability of a solid material to exist in multiple crystalline forms, each having a different arrangement of molecules in the crystal lattice. These different forms can exhibit variations in physical properties such as solubility, dissolution rate, stability, and bioavailability, which are critical for drug formulation and therapeutic efficacy. The patent claims at least three specific crystalline forms of zolpidem tartrate, identified as Form A, Form B, and Form C. These forms are characterized by their unique X-ray powder diffraction (XRPD) patterns, infrared (IR) spectroscopy data, and differential scanning calorimetry (DSC) profiles. Form A: Described as a stable crystalline form of zolpidem tartrate. Its XRPD pattern exhibits characteristic peaks at specific 2-theta angles. Form B: Identified as another stable crystalline form. It is differentiated from Form A by its distinct XRPD pattern. Form C: Also claimed as a stable crystalline form, with its own unique XRPD signature. The specification suggests that these crystalline forms were developed to provide improved stability and/or manufacturing advantages compared to amorphous or other crystalline forms of zolpidem tartrate. By securing patent protection for these specific solid-state forms, Sanofi-Synthelabo aimed to extend market exclusivity for its zolpidem tartrate products beyond the expiration of earlier patents covering the compound itself or its initial pharmaceutical compositions. What are the Key Claims within Patent 6,319,913? United States Patent 6,319,913 contains several claims that define the boundaries of its intellectual property protection. The most significant claims relate to the specific crystalline forms of zolpidem tartrate. Claim 1: This independent claim is central to the patent's scope. It claims a crystalline form of zolpidem tartrate that is characterized by its X-ray powder diffraction pattern having characteristic peaks at specified 2-theta angles. This claim provides a method for identifying and distinguishing this specific crystalline form based on its diffraction fingerprint. Claim 2: This claim defines another specific crystalline form of zolpidem tartrate, also characterized by its X-ray powder diffraction pattern, with a different set of characteristic peaks. This claim protects a distinct polymorphic form. Claim 3: This claim defines a third specific crystalline form of zolpidem tartrate, again characterized by its unique X-ray powder diffraction pattern. Dependent Claims: The patent also includes dependent claims that further narrow the scope or describe specific aspects of the claimed crystalline forms. These might include: Claims specifying that the crystalline form is substantially free of other polymorphic forms. Claims that incorporate additional characterization data, such as IR spectroscopy or DSC thermograms, in conjunction with the XRPD data. Claims for pharmaceutical compositions comprising one or more of the claimed crystalline forms of zolpidem tartrate. Claims for methods of treating insomnia or other sleep disorders using such compositions. The precise wording of these claims determines what activities constitute infringement. Generally, any party that manufactures, uses, sells, or imports zolpidem tartrate in one of the specifically claimed crystalline forms within the United States, without authorization from the patent holder, would be considered an infringer. The emphasis on specific crystalline forms means that generic manufacturers may be able to develop non-infringing formulations by utilizing alternative polymorphic forms, or amorphous forms, of zolpidem tartrate, provided these are not covered by other existing patents. What is the Patent Landscape for Zolpidem Tartrate and its Polymorphs? The patent landscape for zolpidem tartrate is complex, reflecting its long history as a commercially successful drug. United States Patent 6,319,913 is a key component of this landscape, specifically addressing the solid-state forms of the API. Early Patents: The initial patents covering zolpidem itself and its basic pharmaceutical compositions were filed and granted much earlier. For instance, the foundational patent for zolpidem was held by Synthelabo (now part of Sanofi). These early patents established the existence and therapeutic utility of the compound. Polymorph Patents: United States Patent 6,319,913, filed on November 5, 1999, and granted on October 2, 2001, is an example of a "polymorph patent." These patents are often filed later in a drug's lifecycle to provide extended protection for specific solid-state forms of an existing API. The rationale is that while the compound itself may be off-patent or close to expiring, a novel and advantageous crystalline form can be considered a new invention. Key Patent Expirations: The primary patents covering zolpidem tartrate have long since expired. For example, the original composition of matter patents would have expired in the early to mid-2000s. The expiration of United States Patent 6,319,913, which has a term extending 20 years from its filing date (November 5, 1999), means its protection ended on November 5, 2019. This date is significant as it marks the point after which the specific crystalline forms claimed in this patent are no longer protected by this particular patent. Impact on Generic Competition: The expiration of United States Patent 6,319,913, along with the expiration of earlier foundational patents, has facilitated the entry of generic versions of zolpidem tartrate into the market. Generic manufacturers can now produce and market zolpidem tartrate without infringing on the intellectual property rights previously held by Sanofi-Synthelabo. However, it is crucial for generic companies to ensure that their chosen crystalline form of zolpidem tartrate does not infringe on any currently active patents, which might cover other polymorphs, specific formulations, or manufacturing processes. Other Related Intellectual Property: The patent landscape may also include patents related to: Other Polymorphs: It is possible that other polymorphic forms of zolpidem tartrate exist or have been patented by Sanofi or other entities, which may have different expiration dates. Formulations: Patents may exist for specific drug delivery systems or formulations of zolpidem tartrate, such as extended-release versions (e.g., Ambien CR), which may have their own patent protection and expiration timelines. Manufacturing Processes: Novel and inventive methods for synthesizing or crystallizing zolpidem tartrate could also be patented. Combinations: Patents might cover combinations of zolpidem tartrate with other active ingredients. Therefore, while United States Patent 6,319,913 has expired, a comprehensive freedom-to-operate analysis would necessitate a review of all other relevant patents for zolpidem tartrate and its formulations that may still be in force. What are the Commercial Implications of Patent 6,319,913's Claims and Expiration? The commercial implications of United States Patent 6,319,913 are primarily linked to its role in extending market exclusivity and its subsequent expiration facilitating generic market entry. Market Exclusivity Extension: When granted, United States Patent 6,319,913 provided Sanofi-Synthelabo with a period of extended market exclusivity for zolpidem tartrate in specific crystalline forms. This allowed the company to maintain a competitive advantage and command premium pricing for its branded zolpidem products, such as Ambien and Ambien CR, even as earlier patents expired. The protection of specific polymorphs is a common strategy in the pharmaceutical industry to extend a drug's patent life beyond the initial composition of matter and formulation patents. By identifying and patenting novel crystalline forms with desirable properties (e.g., enhanced stability, improved dissolution profiles, easier manufacturing), companies can create new intellectual property that blocks competitors from using those specific forms. Facilitation of Generic Competition: The expiration of United States Patent 6,319,913 on November 5, 2019, removed a significant barrier to generic competition for zolpidem tartrate. Once the patent protection for these specific crystalline forms lapsed, generic pharmaceutical manufacturers were legally free to develop and market their own versions of zolpidem tartrate that utilized these previously protected forms. This has led to a substantial increase in the availability of generic zolpidem tartrate products, which are typically offered at lower prices than the branded version. The entry of generics intensifies competition, drives down prices, and increases patient access to the medication. Impact on Pricing and Market Share: Prior to the expiration of this patent and others, Sanofi-Synthelabo held a dominant position in the zolpidem tartrate market. Following patent expirations, the market share of branded Ambien has significantly declined as generic versions have captured a substantial portion of the market. This shift is accompanied by a dramatic reduction in the average selling price of zolpidem tartrate due to price competition among multiple generic manufacturers. R&D and Investment Considerations: For pharmaceutical companies involved in R&D or investment in the sleep disorder therapeutic area, understanding the patent expiry dates of key drugs like zolpidem tartrate is critical. For Innovator Companies: The expiration of such patents signals the end of a revenue stream and necessitates a focus on developing new, patent-protected products to replace lost exclusivity. For Generic Companies: Patent expiration dates are key milestones that trigger opportunities for market entry. Companies will conduct detailed freedom-to-operate analyses to identify non-infringing development paths. For Investors: Knowledge of patent lifecycles informs investment decisions, allowing for the identification of companies poised to benefit from patent expirations or those facing revenue declines due to generic competition. Manufacturing and Formulation Strategies: The existence of polymorph patents like 6,319,913 influences manufacturing and formulation strategies. Pre-Expiration: Companies seeking to enter the market prior to the patent's expiration would have had to develop alternative crystalline forms or amorphous forms of zolpidem tartrate that were not covered by the patent. This could involve significant R&D investment to identify and characterize such forms and to demonstrate their bioequivalence and stability. Post-Expiration: With the patent expired, manufacturers can now utilize the patented crystalline forms, potentially simplifying their development and manufacturing processes if those forms offer significant advantages. In summary, Patent 6,319,913 played a role in the commercial lifecycle of zolpidem tartrate by extending its market exclusivity. Its expiration has had a profound impact on the market by opening the door for widespread generic competition, leading to price reductions and increased patient access. What is the Status of Patent 6,319,913? United States Patent 6,319,913 has expired. The patent was filed on November 5, 1999, and granted on October 2, 2001. Under U.S. patent law, utility patents generally have a term of 20 years from the filing date. Therefore, the statutory term for United States Patent 6,319,913 ended on November 5, 2019. This means that the patent protection originally granted for the specific crystalline forms of zolpidem tartrate described and claimed in this patent is no longer in force. The expiration of this patent has significant implications: It removes the patent-based restriction on the use, sale, and manufacture of zolpidem tartrate in the crystalline forms claimed by this patent within the United States. It allows generic pharmaceutical companies to utilize these specific crystalline forms in their own zolpidem tartrate products without infringing on this particular patent. It is important to note that the expiration of this patent does not necessarily mean that all intellectual property protection related to zolpidem tartrate has ended. Other patents, such as those covering different polymorphic forms, specific pharmaceutical formulations (e.g., extended-release versions), or manufacturing processes, may still be in effect or may have expired at different times. However, the protection specifically afforded by Patent 6,319,913 for its claimed crystalline forms has concluded. What are the Key Takeaways? United States Patent 6,319,913 protected specific crystalline polymorphic forms (Forms A, B, and C) of zolpidem tartrate, the active ingredient in Ambien. The patent's claims were based on the unique solid-state characteristics of these crystalline forms, primarily defined by X-ray powder diffraction patterns. This patent served as a mechanism to extend market exclusivity for zolpidem tartrate beyond the expiration of earlier composition of matter patents. The patent term for United States Patent 6,319,913 expired on November 5, 2019, 20 years from its filing date. The expiration of this patent has enabled the widespread entry of generic zolpidem tartrate products into the U.S. market, leading to increased competition and reduced prices. While this specific patent has expired, a comprehensive freedom-to-operate analysis for zolpidem tartrate would still require consideration of any other potentially active patents covering different polymorphs, formulations, or manufacturing processes. Frequently Asked Questions 1. Did patent 6,319,913 cover zolpidem itself, or specific forms of it? Patent 6,319,913 specifically covered crystalline polymorphic forms of zolpidem tartrate, not zolpidem or zolpidem tartrate in general. Earlier patents would have covered the compound itself. 2. What is the significance of "crystalline forms" in pharmaceutical patents? Crystalline forms, or polymorphs, are different solid-state structures of the same chemical compound. They can have varying physical properties such as solubility, stability, and dissolution rate, which impact manufacturing and therapeutic efficacy. Patenting specific advantageous polymorphs allows innovators to extend market exclusivity beyond original composition of matter patents. 3. Does the expiration of patent 6,319,913 mean all zolpidem patents have expired? No, the expiration of patent 6,319,913 means protection for the specific crystalline forms it claimed has ended. Other patents related to different zolpidem tartrate polymorphs, pharmaceutical compositions (e.g., extended-release formulations), or manufacturing processes may still be in force or have expired at different times. 4. What does it mean for a generic company if patent 6,319,913 has expired? It means generic companies are now free to manufacture and sell zolpidem tartrate using the crystalline forms that were protected by this specific patent, provided they do not infringe on any other currently active patents. 5. Can a company be sued for patent infringement if patent 6,319,913 is expired? A company cannot be sued for infringement of patent 6,319,913 if the alleged infringement occurred after its expiration date of November 5, 2019. However, they could still face infringement claims if their product or process violates the terms of any other currently active and relevant patents. Citations [1] Sanofi-Synthelabo. (2001). Crystalline Forms of Zolpidem Tartrate. U.S. Patent 6,319,913. Washington, D.C.: U.S. Patent and Trademark Office. More… ↓ ⤷ Start Trial

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Details for Patent: 6,319,913

Summary for Patent: 6,319,913