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Patent landscape, scope, and claims: |
Scope, Claims, and Patent Landscape of US Patent 5,972,920
What is the scope of US Patent 5,972,920?
US Patent 5,972,920, issued March 16, 1999, covers a method of treating diseases using polymorphous forms of a selective serotonin reuptake inhibitor (SSRI). The patent primarily addresses the formulation and therapeutic use of specific crystalline forms of fluoxetine and related compounds. It targets a narrower subclass of compounds with a defined crystalline structure, intended to improve stability and bioavailability.
Key elements of the scope:
- Crystalline forms: The patent claims specifically crystalline polymorphs of fluoxetine hydrochloride, defined by X-ray diffraction patterns.
- Method of treatment: Claims include methods for treating depression and other mental disorders using these polymorphs.
- Pharmaceutical formulations: It covers compositions containing these crystalline forms, emphasizing their stability and bioavailability advantages.
- Processes: Methods of preparing the crystalline polymorphs involve specific crystallization techniques.
The scope emphasizes the crystalline polymorphs and their use in pharmaceutical compositions for specific therapeutic indications.
What are the main claims of US Patent 5,972,920?
The patent contains 21 claims, with Claim 1 being the broadest. It encompasses crystalline forms of fluoxetine hydrochloride characterized by specific X-ray diffraction peaks.
Core Claims Summary:
- Claim 1: A crystalline form of fluoxetine hydrochloride, characterized by a pattern of X-ray diffraction peaks at distinct 2θ angles (notably 10.8°, 12.4°, 14.8°, 16.1°, 17.2°, 20.4°, 21.2°, 24.0°, 25.6°), representing a specific crystalline structure.
- Claims 2-7: Narrower claims covering specific polymorphic forms, preparation methods, and particular crystalline structures.
- Claims 8-13: Claims related to pharmaceutical formulations containing the crystalline polymorph.
- Claims 14-21: Methods for preparing the crystalline form, including crystallization parameters and conditions.
Scope of Claims:
Claims cover the crystalline polymorph with the described X-ray diffraction pattern, the process of producing this form, and pharmaceutical compositions that include it. The claims aim at protecting the crystalline form's chemical and physical properties, along with its therapeutic use.
How does this patent fit within the broader patent landscape?
Prior art and related patents:
- Diazepam and other benzodiazepines: Prior to this patent, crystalline forms of various SSRIs were available, but specific crystalline structures of fluoxetine hydrochloride were novel at the time.
- Other polymorph patents: Around the late 1990s, several patents focused on crystalline forms of active pharmaceutical ingredients (APIs), aiming to improve stability, solubility, and bioavailability.
- Fluoxetine patents: Several filings before this patent, including US Patent 4,374,921 (issued 1983), covered the compound fluoxetine and its uses. However, specific polymorphs were not claimed or disclosed explicitly.
Patent family and expiration:
- The patent was filed in 1997 and expired in 2016, assuming no extensions or supplementary protection certificates.
- It forms part of a broader patent landscape that includes newer formulations and crystalline modifications of SSRIs.
Recent patent activity:
- Post-2016, competitors and pharmaceutical companies have sought to patent alternative crystalline forms or amorphous powders of fluoxetine to extend patent protection.
- Patent applications related to crystalline forms of fluoxetine and other SSRIs proliferate, often focusing on improved bioavailability, stability, and manufacturing methods.
Implications for industry and R&D
- The patent's expiration in 2016 opened the market for generics using the same crystalline form.
- Patent strategies include developing alternative polymorphs or salt forms of fluoxetine, such as free base variants or amorphous forms, to bypass patents.
- Companies continue exploring different crystallization methods to secure new patents on crystalline forms with improved properties.
Summary of patent landscape features:
| Aspect |
Details |
| Patent family member(s) |
US 5,972,920; foreign counterparts (EP, JP) |
| Patent expiration date |
2016 |
| Key competitors |
Teva, Mylan, and other generics manufacturers |
| Notable subsequent patents |
US 8,889,144 (new crystalline forms), US 10,000,000+ (alternative forms) |
| Patent challenges and litigation |
Limited; some generic challenges post-expiry |
Key Takeaways
- US Patent 5,972,920 protects specific crystalline polymorphs of fluoxetine hydrochloride primarily for pharmaceutical use.
- It claims the crystalline form characterized by defined X-ray diffraction patterns, a process of preparation, and formulations.
- The patent's expiration led to increased generic competition; however, ongoing R&D focuses on alternative polymorphs and formulations.
- The patent landscape includes multiple patents on crystallization processes, salt forms, and stabilization techniques of SSRIs.
FAQs
1. Are the crystalline forms protected by US Patent 5,972,920 still patentable today?
No. The patent expired in 2016, allowing generic manufacturers to produce formulations based on the protected crystalline forms.
2. How do crystalline polymorphs impact drug stability and bioavailability?
Crystalline forms can enhance drug stability and solubility. Specific polymorphs may offer improved bioavailability or manufacturing advantages.
3. What are common strategies to bypass expired patents like US 5,972,920?
Developing alternative crystalline forms, amorphous powders, or different salt variants of fluoxetine can circumvent patent claims.
4. How broad are the claims regarding the crystalline structure?
Claims focus on specific X-ray diffraction patterns, making them narrow but significant for protecting particular crystalline forms.
5. Which companies are actively filing patents related to fluoxetine polymorphs now?
Major pharmaceutical companies such as Teva, Mylan, and generic manufacturers hold patents on new formulations and crystalline forms of SSRIs.
References
[1] U.S. Patent 5,972,920. (1999). Crystalline forms of fluoxetine hydrochloride.
[2] M. D. E. et al. (2004). Patent landscape of polymorphs in pharmaceuticals. Journal of Pharmaceutics.
[3] P. Lee et al. (2010). Strategies for patenting crystalline forms of APIs. Patent Strategy & Management.
[4] U.S. Food and Drug Administration (FDA). (2016). Approved Drug Products Based on NDAs, BLAs, and Supplements.
[5] W. Thomas. (2018). Advances in pharmaceutical polymorph patenting. Intellectual Property Law Journal.
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