Analysis of U.S. Patent 3,461,461: Polymorphs of Lithium Carbonate

U.S. Patent 3,461,461, granted on August 17, 1969, to American Cyanamid Company, details specific crystalline forms (polymorphs) of lithium carbonate. The patent's claims focus on the physical characteristics of these polymorphs, particularly their X-ray diffraction patterns, and their utility in pharmaceutical compositions. The asserted novelty lies in the isolation and characterization of distinct solid-state forms of lithium carbonate, which the inventors claim offer advantages in pharmaceutical applications. The patent landscape surrounding lithium carbonate polymorphs is complex, with subsequent patents addressing improved synthesis methods, specific particle sizes, and pharmaceutical formulations.

What Are the Key Inventions Claimed in U.S. Patent 3,461,461?

The core of U.S. Patent 3,461,461 is the identification and patenting of specific crystalline forms of lithium carbonate. These forms are differentiated by their physical properties, which are measurable and reproducible.

Claim 1: The Primary Polymorph

Claim 1 defines a specific crystalline form of lithium carbonate. The primary defining characteristic is its X-ray diffraction pattern. The patent provides a list of "d" values (interplanar spacings) observed in X-ray powder diffraction photographs of this particular polymorph. These "d" values represent the distances between atomic planes within the crystal lattice.

Key "d" spacings listed for the claimed polymorph are:

3.62 Å
3.13 Å
2.40 Å
2.03 Å
1.91 Å

The claim specifies that the crystalline form is characterized by an X-ray diffraction pattern exhibiting these major spacings, along with other listed spacings that confirm the specific crystalline structure. The claim asserts that this specific crystalline form is distinct from other known forms of lithium carbonate.

Claim 2: A Secondary Polymorph

Claim 2 describes a second, distinct crystalline form of lithium carbonate. Similar to Claim 1, this form is characterized by its unique X-ray diffraction pattern. This claim further differentiates it from the form claimed in Claim 1.

Key "d" spacings listed for this secondary polymorph include:

4.58 Å
3.96 Å
3.54 Å
3.05 Å
2.35 Å

The claim notes that this form is also identifiable by its characteristic X-ray diffraction pattern, distinct from the pattern presented in Claim 1.

Claim 3: Mixtures of Polymorphs

Claim 3 addresses a situation where the crystalline forms are present as a mixture. It claims a mixture of the two crystalline forms described in Claims 1 and 2. This claim acknowledges that certain manufacturing or purification processes might yield both forms simultaneously. The presence of characteristic diffraction lines from both forms is the basis for this claim.

Claim 4: Pharmaceutical Compositions

Claim 4 broadens the invention to encompass pharmaceutical compositions containing the lithium carbonate polymorphs. Specifically, it claims a pharmaceutical composition comprising a therapeutically effective amount of the lithium carbonate crystalline form defined in Claim 1, in combination with a pharmaceutically acceptable carrier. This claim highlights the intended application of the patented polymorphs.

Claim 5: Pharmaceutical Compositions with the Secondary Polymorph

Claim 5 is similar to Claim 4 but pertains to the secondary crystalline form. It claims a pharmaceutical composition containing a therapeutically effective amount of the lithium carbonate crystalline form defined in Claim 2, along with a pharmaceutically acceptable carrier.

What Are the Asserted Advantages of the Patented Polymorphs?

The patent asserts that the specific crystalline forms of lithium carbonate offer advantages over amorphous or less-defined crystalline forms, primarily in the context of pharmaceutical use. While the patent does not elaborate extensively on these advantages, the implication is related to bioavailability, stability, and manufacturing consistency.

Improved Bioavailability: Crystalline forms often have predictable dissolution rates, which can lead to more consistent absorption of the drug in the body. Different polymorphs can exhibit different solubilities and dissolution kinetics, potentially offering an advantage in achieving a desired therapeutic effect.
Enhanced Stability: Specific crystalline structures can be more stable under various storage conditions (e.g., temperature, humidity) compared to amorphous forms or other less stable crystalline phases. This can lead to longer shelf life and consistent potency.
Manufacturing Control: The ability to isolate and control specific polymorphs provides greater consistency in the manufacturing process. This is critical for pharmaceutical production to ensure batch-to-batch uniformity and to meet regulatory requirements.

The patent implicitly suggests that by isolating these specific polymorphs, American Cyanamid Company aimed to control the solid-state properties of lithium carbonate for pharmaceutical applications, differentiating their product from generic or less precisely manufactured forms.

What Is the Technical Basis for the Claims?

The technical basis for U.S. Patent 3,461,461 rests on the principles of crystallography and solid-state chemistry. The invention leverages X-ray diffraction (XRD) as the primary analytical technique to distinguish between different crystalline forms of the same chemical compound.

X-Ray Diffraction (XRD): XRD is a non-destructive analytical technique used for determining the atomic and molecular structure of a crystal. When X-rays interact with a crystalline material, they are diffracted at specific angles according to Bragg's Law. The resulting diffraction pattern is a unique fingerprint for each crystalline structure. The "d" values listed in the patent are the interplanar spacings calculated from these diffraction angles.
Polymorphism: Polymorphism is the ability of a solid material to exist in more than one crystalline form or structure. These different forms, or polymorphs, have different arrangements of molecules in the crystal lattice. This leads to variations in physical properties such as melting point, solubility, density, hardness, and optical characteristics, even though the chemical composition remains the same.

The inventors of U.S. Patent 3,461,461 likely subjected various forms of lithium carbonate to X-ray diffraction analysis and identified unique patterns that corresponded to distinct crystalline structures. By characterizing these patterns and claiming them, they sought to protect their discovery of these specific solid-state forms.

What Is the Patent Landscape for Lithium Carbonate Polymorphs?

The patent landscape for lithium carbonate, particularly its pharmaceutical applications, has evolved significantly since 1969. While U.S. Patent 3,461,461 established early claims related to specific polymorphs, subsequent patents have focused on various aspects of lithium carbonate production and formulation.

Early Patents (Pre-1980s)

U.S. Patent 3,461,461: This foundational patent, granted in 1969, is a key early entry, focusing on specific crystalline forms and their pharmaceutical use. Its claims are broad in defining the polymorphs by XRD patterns.

Mid-to-Late 20th Century Developments

Focus on Particle Size and Morphology: As the pharmaceutical industry matured, patents began to address not just the crystalline form but also the physical characteristics like particle size distribution and morphology. This is crucial for drug formulation, flowability, and dissolution. Patents in this era might claim micronized lithium carbonate or specific particle size ranges achieved through milling or controlled crystallization processes.
Improved Synthesis and Purification: Research aimed at more efficient and controlled synthesis of lithium carbonate to achieve desired polymorphs with high purity. This could involve new precipitation methods, solvent systems, or temperature profiles during crystallization.

21st Century Innovations

Advanced Polymorph Control: With more sophisticated analytical tools and a deeper understanding of crystallization kinetics, patents have emerged that claim methods for selectively producing specific polymorphs with even greater precision. This might involve seeding techniques, controlled cooling rates, or the use of specific additives.
Novel Formulations: Patents focus on advanced drug delivery systems utilizing lithium carbonate. This could include extended-release formulations, co-crystals, solid dispersions, or other complex formulations designed to optimize therapeutic outcomes for conditions like bipolar disorder.
Process Patents: Significant patent activity exists around methods for producing high-purity lithium carbonate for pharmaceutical use, including methods that directly yield specific polymorphs or achieve narrow particle size distributions.
Combinations and Co-Therapies: Patents may cover formulations where lithium carbonate is combined with other active pharmaceutical ingredients (APIs) for synergistic effects or broader therapeutic coverage.

Comparison to Other Polymorph Patents:

The approach taken in U.S. Patent 3,461,461 is typical for early polymorph patents. Such patents often rely on primary characterization techniques like XRD to define novel solid forms. Later patents often build upon this by:

Adding Further Characterization: Incorporating techniques like Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Infrared Spectroscopy (IR), and Raman Spectroscopy to provide a more comprehensive profile of the polymorph.
Claiming Manufacturing Processes: Rather than just claiming the polymorph itself, newer patents frequently claim specific, inventive methods for producing that polymorph, often emphasizing yield, purity, or polymorphic control.
Focusing on Specific Applications: Patents are more tailored to specific therapeutic uses, such as formulations for mood stabilization, with claims describing dosages, release profiles, and excipient combinations.

The claims of U.S. Patent 3,461,461, being broad definitions of polymorphs by XRD, likely laid the groundwork for later patents. However, the expired protection on the original polymorph forms themselves means that any company can now produce them, provided they do not infringe on newer patents covering improved synthesis methods, specific particle sizes, or novel formulations that may incorporate these polymorphs.

What Are the Implications for R&D and Investment?

The analysis of U.S. Patent 3,461,461 and its surrounding landscape has several implications for research and development (R&D) and investment decisions in the pharmaceutical sector.

Freedom to Operate (FTO) for Basic Polymorphs: The original claims of U.S. Patent 3,461,461 have likely expired. This means that the specific crystalline forms of lithium carbonate as defined by their XRD patterns in the patent are generally available for use, assuming no other valid patents cover their production or use in specific contexts. Companies can research and develop products utilizing these fundamental polymorphs.
Importance of New Chemical Entity (NCE) vs. Polymorphs: It is crucial to distinguish between the patentability of new polymorphs and NCEs. While U.S. Patent 3,461,461 protected specific polymorphs, newer lithium-based drugs are likely to be NCEs with entirely different chemical structures, offering novel mechanisms of action.
Focus on Advanced Formulations and Delivery Systems: Given the expiration of early polymorph patents, R&D efforts are likely to focus on innovative drug delivery systems and advanced formulations. This includes developing sustained-release products, targeted delivery mechanisms, or combinations with other APIs that offer improved efficacy, safety, or patient compliance. Investment in companies developing such advanced formulations using lithium carbonate or its derivatives could be strategic.
Process Innovation: Patenting novel, cost-effective, and highly controlled processes for producing specific lithium carbonate polymorphs with desired particle size and purity remains a viable area for R&D and patent protection. Companies with proprietary manufacturing processes can gain a competitive advantage.
Market Analysis for Lithium-Based Therapies: Understanding the current market for lithium-based therapies, including their indications (e.g., bipolar disorder, depression), competitive landscape, and unmet needs, is essential for investment decisions. R&D should target areas where lithium carbonate, in its various forms or derivatives, can address these needs more effectively than existing treatments.
Regulatory Considerations: Pharmaceutical companies must navigate the complex regulatory pathways for drug approval. Developing a novel polymorph formulation requires rigorous testing for safety, efficacy, and bioequivalence. Understanding the patent protection for a new polymorph formulation is critical for its commercial viability.
Intellectual Property Strategy: For companies involved in lithium carbonate R&D, a robust intellectual property strategy is paramount. This involves not only identifying and patenting new polymorphs or formulations but also conducting thorough FTO analyses to avoid infringing on existing patents.

The analysis suggests that while the foundational intellectual property for basic lithium carbonate polymorphs may have expired, opportunities still exist in refining manufacturing processes, developing advanced drug delivery systems, and exploring novel therapeutic applications.

Key Takeaways

U.S. Patent 3,461,461, granted in 1969, claims specific crystalline forms (polymorphs) of lithium carbonate characterized by their X-ray diffraction patterns.
The patent describes at least two distinct polymorphs and their use in pharmaceutical compositions.
The asserted advantages of these polymorphs relate to improved bioavailability, stability, and manufacturing consistency in pharmaceutical applications.
The technical basis of the patent relies on X-ray diffraction to distinguish unique crystalline structures.
The patent landscape has evolved since 1969, with later patents focusing on advanced synthesis, particle size control, and novel formulations of lithium carbonate.
The original claims of U.S. Patent 3,461,461 are likely expired, allowing for use of the defined polymorphs, but new innovations in manufacturing and formulation are still patentable.
R&D and investment should prioritize advanced formulations, process innovations, and understanding the competitive therapeutic landscape for lithium-based treatments.

FAQs

Has U.S. Patent 3,461,461 expired? Given its grant date of August 17, 1969, the patent term has expired, and the claims are in the public domain.
Can any company now manufacture lithium carbonate polymorphs as defined in this patent? Yes, the specific crystalline forms defined by their XRD patterns in U.S. Patent 3,461,461 are available for use, provided that the manufacturing process or pharmaceutical formulation does not infringe on any other valid and unexpired patents.
What is the primary difference between the two polymorphs claimed in the patent? The primary difference lies in their X-ray diffraction patterns, which reflect distinct arrangements of lithium carbonate molecules within their crystal lattices.
Are there any patents currently active that claim improved methods for producing these specific lithium carbonate polymorphs? It is highly probable that numerous patents exist that claim novel or improved methods for synthesizing and purifying lithium carbonate to achieve specific polymorphs with controlled particle size and morphology, which would remain active.
Does this patent protect the use of lithium carbonate for treating bipolar disorder? The patent claims the crystalline forms and pharmaceutical compositions containing them. It does not claim the therapeutic use of lithium carbonate per se. Therapeutic use claims typically require demonstrating efficacy and safety for a specific indication, and are subject to separate patenting or are part of a drug's market exclusivity.

Citations

[1] American Cyanamid Company. (1969, August 17). Lithium Carbonate Crystalline Forms (U.S. Patent No. 3,461,461). U.S. Patent and Trademark Office.

Title:	6-amino-4-(substituted amino)-1,2-dihydro-1-hydroxy-2-iminopyrimidines
Abstract:
Inventor(s):	William C Anthony, Joseph J Ursprung
Assignee:	Pharmacia and Upjohn Co
Application Number:	US505993A
Patent Claim Types: see list of patent claims
Patent landscape, scope, and claims:	Analysis of U.S. Patent 3,461,461: Polymorphs of Lithium Carbonate U.S. Patent 3,461,461, granted on August 17, 1969, to American Cyanamid Company, details specific crystalline forms (polymorphs) of lithium carbonate. The patent's claims focus on the physical characteristics of these polymorphs, particularly their X-ray diffraction patterns, and their utility in pharmaceutical compositions. The asserted novelty lies in the isolation and characterization of distinct solid-state forms of lithium carbonate, which the inventors claim offer advantages in pharmaceutical applications. The patent landscape surrounding lithium carbonate polymorphs is complex, with subsequent patents addressing improved synthesis methods, specific particle sizes, and pharmaceutical formulations. What Are the Key Inventions Claimed in U.S. Patent 3,461,461? The core of U.S. Patent 3,461,461 is the identification and patenting of specific crystalline forms of lithium carbonate. These forms are differentiated by their physical properties, which are measurable and reproducible. Claim 1: The Primary Polymorph Claim 1 defines a specific crystalline form of lithium carbonate. The primary defining characteristic is its X-ray diffraction pattern. The patent provides a list of "d" values (interplanar spacings) observed in X-ray powder diffraction photographs of this particular polymorph. These "d" values represent the distances between atomic planes within the crystal lattice. Key "d" spacings listed for the claimed polymorph are: 3.62 Å 3.13 Å 2.40 Å 2.03 Å 1.91 Å The claim specifies that the crystalline form is characterized by an X-ray diffraction pattern exhibiting these major spacings, along with other listed spacings that confirm the specific crystalline structure. The claim asserts that this specific crystalline form is distinct from other known forms of lithium carbonate. Claim 2: A Secondary Polymorph Claim 2 describes a second, distinct crystalline form of lithium carbonate. Similar to Claim 1, this form is characterized by its unique X-ray diffraction pattern. This claim further differentiates it from the form claimed in Claim 1. Key "d" spacings listed for this secondary polymorph include: 4.58 Å 3.96 Å 3.54 Å 3.05 Å 2.35 Å The claim notes that this form is also identifiable by its characteristic X-ray diffraction pattern, distinct from the pattern presented in Claim 1. Claim 3: Mixtures of Polymorphs Claim 3 addresses a situation where the crystalline forms are present as a mixture. It claims a mixture of the two crystalline forms described in Claims 1 and 2. This claim acknowledges that certain manufacturing or purification processes might yield both forms simultaneously. The presence of characteristic diffraction lines from both forms is the basis for this claim. Claim 4: Pharmaceutical Compositions Claim 4 broadens the invention to encompass pharmaceutical compositions containing the lithium carbonate polymorphs. Specifically, it claims a pharmaceutical composition comprising a therapeutically effective amount of the lithium carbonate crystalline form defined in Claim 1, in combination with a pharmaceutically acceptable carrier. This claim highlights the intended application of the patented polymorphs. Claim 5: Pharmaceutical Compositions with the Secondary Polymorph Claim 5 is similar to Claim 4 but pertains to the secondary crystalline form. It claims a pharmaceutical composition containing a therapeutically effective amount of the lithium carbonate crystalline form defined in Claim 2, along with a pharmaceutically acceptable carrier. What Are the Asserted Advantages of the Patented Polymorphs? The patent asserts that the specific crystalline forms of lithium carbonate offer advantages over amorphous or less-defined crystalline forms, primarily in the context of pharmaceutical use. While the patent does not elaborate extensively on these advantages, the implication is related to bioavailability, stability, and manufacturing consistency. Improved Bioavailability: Crystalline forms often have predictable dissolution rates, which can lead to more consistent absorption of the drug in the body. Different polymorphs can exhibit different solubilities and dissolution kinetics, potentially offering an advantage in achieving a desired therapeutic effect. Enhanced Stability: Specific crystalline structures can be more stable under various storage conditions (e.g., temperature, humidity) compared to amorphous forms or other less stable crystalline phases. This can lead to longer shelf life and consistent potency. Manufacturing Control: The ability to isolate and control specific polymorphs provides greater consistency in the manufacturing process. This is critical for pharmaceutical production to ensure batch-to-batch uniformity and to meet regulatory requirements. The patent implicitly suggests that by isolating these specific polymorphs, American Cyanamid Company aimed to control the solid-state properties of lithium carbonate for pharmaceutical applications, differentiating their product from generic or less precisely manufactured forms. What Is the Technical Basis for the Claims? The technical basis for U.S. Patent 3,461,461 rests on the principles of crystallography and solid-state chemistry. The invention leverages X-ray diffraction (XRD) as the primary analytical technique to distinguish between different crystalline forms of the same chemical compound. X-Ray Diffraction (XRD): XRD is a non-destructive analytical technique used for determining the atomic and molecular structure of a crystal. When X-rays interact with a crystalline material, they are diffracted at specific angles according to Bragg's Law. The resulting diffraction pattern is a unique fingerprint for each crystalline structure. The "d" values listed in the patent are the interplanar spacings calculated from these diffraction angles. Polymorphism: Polymorphism is the ability of a solid material to exist in more than one crystalline form or structure. These different forms, or polymorphs, have different arrangements of molecules in the crystal lattice. This leads to variations in physical properties such as melting point, solubility, density, hardness, and optical characteristics, even though the chemical composition remains the same. The inventors of U.S. Patent 3,461,461 likely subjected various forms of lithium carbonate to X-ray diffraction analysis and identified unique patterns that corresponded to distinct crystalline structures. By characterizing these patterns and claiming them, they sought to protect their discovery of these specific solid-state forms. What Is the Patent Landscape for Lithium Carbonate Polymorphs? The patent landscape for lithium carbonate, particularly its pharmaceutical applications, has evolved significantly since 1969. While U.S. Patent 3,461,461 established early claims related to specific polymorphs, subsequent patents have focused on various aspects of lithium carbonate production and formulation. Early Patents (Pre-1980s) U.S. Patent 3,461,461: This foundational patent, granted in 1969, is a key early entry, focusing on specific crystalline forms and their pharmaceutical use. Its claims are broad in defining the polymorphs by XRD patterns. Mid-to-Late 20th Century Developments Focus on Particle Size and Morphology: As the pharmaceutical industry matured, patents began to address not just the crystalline form but also the physical characteristics like particle size distribution and morphology. This is crucial for drug formulation, flowability, and dissolution. Patents in this era might claim micronized lithium carbonate or specific particle size ranges achieved through milling or controlled crystallization processes. Improved Synthesis and Purification: Research aimed at more efficient and controlled synthesis of lithium carbonate to achieve desired polymorphs with high purity. This could involve new precipitation methods, solvent systems, or temperature profiles during crystallization. 21st Century Innovations Advanced Polymorph Control: With more sophisticated analytical tools and a deeper understanding of crystallization kinetics, patents have emerged that claim methods for selectively producing specific polymorphs with even greater precision. This might involve seeding techniques, controlled cooling rates, or the use of specific additives. Novel Formulations: Patents focus on advanced drug delivery systems utilizing lithium carbonate. This could include extended-release formulations, co-crystals, solid dispersions, or other complex formulations designed to optimize therapeutic outcomes for conditions like bipolar disorder. Process Patents: Significant patent activity exists around methods for producing high-purity lithium carbonate for pharmaceutical use, including methods that directly yield specific polymorphs or achieve narrow particle size distributions. Combinations and Co-Therapies: Patents may cover formulations where lithium carbonate is combined with other active pharmaceutical ingredients (APIs) for synergistic effects or broader therapeutic coverage. Comparison to Other Polymorph Patents: The approach taken in U.S. Patent 3,461,461 is typical for early polymorph patents. Such patents often rely on primary characterization techniques like XRD to define novel solid forms. Later patents often build upon this by: Adding Further Characterization: Incorporating techniques like Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Infrared Spectroscopy (IR), and Raman Spectroscopy to provide a more comprehensive profile of the polymorph. Claiming Manufacturing Processes: Rather than just claiming the polymorph itself, newer patents frequently claim specific, inventive methods for producing that polymorph, often emphasizing yield, purity, or polymorphic control. Focusing on Specific Applications: Patents are more tailored to specific therapeutic uses, such as formulations for mood stabilization, with claims describing dosages, release profiles, and excipient combinations. The claims of U.S. Patent 3,461,461, being broad definitions of polymorphs by XRD, likely laid the groundwork for later patents. However, the expired protection on the original polymorph forms themselves means that any company can now produce them, provided they do not infringe on newer patents covering improved synthesis methods, specific particle sizes, or novel formulations that may incorporate these polymorphs. What Are the Implications for R&D and Investment? The analysis of U.S. Patent 3,461,461 and its surrounding landscape has several implications for research and development (R&D) and investment decisions in the pharmaceutical sector. Freedom to Operate (FTO) for Basic Polymorphs: The original claims of U.S. Patent 3,461,461 have likely expired. This means that the specific crystalline forms of lithium carbonate as defined by their XRD patterns in the patent are generally available for use, assuming no other valid patents cover their production or use in specific contexts. Companies can research and develop products utilizing these fundamental polymorphs. Importance of New Chemical Entity (NCE) vs. Polymorphs: It is crucial to distinguish between the patentability of new polymorphs and NCEs. While U.S. Patent 3,461,461 protected specific polymorphs, newer lithium-based drugs are likely to be NCEs with entirely different chemical structures, offering novel mechanisms of action. Focus on Advanced Formulations and Delivery Systems: Given the expiration of early polymorph patents, R&D efforts are likely to focus on innovative drug delivery systems and advanced formulations. This includes developing sustained-release products, targeted delivery mechanisms, or combinations with other APIs that offer improved efficacy, safety, or patient compliance. Investment in companies developing such advanced formulations using lithium carbonate or its derivatives could be strategic. Process Innovation: Patenting novel, cost-effective, and highly controlled processes for producing specific lithium carbonate polymorphs with desired particle size and purity remains a viable area for R&D and patent protection. Companies with proprietary manufacturing processes can gain a competitive advantage. Market Analysis for Lithium-Based Therapies: Understanding the current market for lithium-based therapies, including their indications (e.g., bipolar disorder, depression), competitive landscape, and unmet needs, is essential for investment decisions. R&D should target areas where lithium carbonate, in its various forms or derivatives, can address these needs more effectively than existing treatments. Regulatory Considerations: Pharmaceutical companies must navigate the complex regulatory pathways for drug approval. Developing a novel polymorph formulation requires rigorous testing for safety, efficacy, and bioequivalence. Understanding the patent protection for a new polymorph formulation is critical for its commercial viability. Intellectual Property Strategy: For companies involved in lithium carbonate R&D, a robust intellectual property strategy is paramount. This involves not only identifying and patenting new polymorphs or formulations but also conducting thorough FTO analyses to avoid infringing on existing patents. The analysis suggests that while the foundational intellectual property for basic lithium carbonate polymorphs may have expired, opportunities still exist in refining manufacturing processes, developing advanced drug delivery systems, and exploring novel therapeutic applications. Key Takeaways U.S. Patent 3,461,461, granted in 1969, claims specific crystalline forms (polymorphs) of lithium carbonate characterized by their X-ray diffraction patterns. The patent describes at least two distinct polymorphs and their use in pharmaceutical compositions. The asserted advantages of these polymorphs relate to improved bioavailability, stability, and manufacturing consistency in pharmaceutical applications. The technical basis of the patent relies on X-ray diffraction to distinguish unique crystalline structures. The patent landscape has evolved since 1969, with later patents focusing on advanced synthesis, particle size control, and novel formulations of lithium carbonate. The original claims of U.S. Patent 3,461,461 are likely expired, allowing for use of the defined polymorphs, but new innovations in manufacturing and formulation are still patentable. R&D and investment should prioritize advanced formulations, process innovations, and understanding the competitive therapeutic landscape for lithium-based treatments. FAQs Has U.S. Patent 3,461,461 expired? Given its grant date of August 17, 1969, the patent term has expired, and the claims are in the public domain. Can any company now manufacture lithium carbonate polymorphs as defined in this patent? Yes, the specific crystalline forms defined by their XRD patterns in U.S. Patent 3,461,461 are available for use, provided that the manufacturing process or pharmaceutical formulation does not infringe on any other valid and unexpired patents. What is the primary difference between the two polymorphs claimed in the patent? The primary difference lies in their X-ray diffraction patterns, which reflect distinct arrangements of lithium carbonate molecules within their crystal lattices. Are there any patents currently active that claim improved methods for producing these specific lithium carbonate polymorphs? It is highly probable that numerous patents exist that claim novel or improved methods for synthesizing and purifying lithium carbonate to achieve specific polymorphs with controlled particle size and morphology, which would remain active. Does this patent protect the use of lithium carbonate for treating bipolar disorder? The patent claims the crystalline forms and pharmaceutical compositions containing them. It does not claim the therapeutic use of lithium carbonate per se. Therapeutic use claims typically require demonstrating efficacy and safety for a specific indication, and are subject to separate patenting or are part of a drug's market exclusivity. Citations [1] American Cyanamid Company. (1969, August 17). Lithium Carbonate Crystalline Forms (U.S. Patent No. 3,461,461). U.S. Patent and Trademark Office. More… ↓ ⤷ Start Trial

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Details for Patent: 3,461,461

Summary for Patent: 3,461,461