Overview of US Patent 5,234,404
US Patent 5,234,404, granted to Eli Lilly and Company on August 10, 1993, primarily covers a method of treating depression using selective serotonin reuptake inhibitors (SSRIs), specifically fluoxetine. This patent, titled "Method of Treating Depression with Fluoxetine," provides broad coverage for the administration of fluoxetine for depressive disorders. It claims both methods and formulations related to fluoxetine therapy.
Scope and Claims of US Patent 5,234,404
Main Claims
- Method of Treatment: The patent claims the use of fluoxetine in the treatment of depression, particularly in a specified dose range. It emphasizes administration in doses between 10 mg and 80 mg daily.
- Therapeutic Indications: The patent explicitly states the treatment of depressive disorders, including major depression, dysthymia, and atypical depression.
- Formulations: The patent encompasses various formulations containing fluoxetine, including capsules and tablets, without specific limitations on excipients or carriers.
- Duration of Treatment: The claims include methods where the administration continues until clinical remission or improvement, with no fixed duration.
Scope Analysis
- The claims are broad for the method of administering fluoxetine to treat depression, covering any form or dose within the specified range.
- Specific formulations are not limited to particular excipients, thus allowing a range of generic formulations.
- The focus is on therapeutic method claims, which are generally easier to invalidate if prior art demonstrates similar treatments.
Limitations
- The patent does not specify precise dosing regimens beyond the range.
- It does not limit the patient population further, such as age, severity, or comorbidities.
- No specific biomarkers or diagnostic criteria are required, broadening the scope to general depressive episodes.
Patent Landscape and Legal Status
Initial Market Impact
- The patent played a significant role during the 1990s and early 2000s, providing Lilly with compound and method exclusivity for fluoxetine until expiry.
- It was a foundational patent alongside a series of related patents covering dosage forms and uses, shaping the market for SSRIs.
Expiration and Patent Term
- Expiry date: July 22, 2003, calculated based on the filing date (May 3, 1990) and term adjustments.
- Post-expiry, generic manufacturers gained legal freedom to produce fluoxetine formulations, significantly increasing market competition and lowering prices.
Legal Challenges and Litigation
- The patent faced challenges from generic firms seeking to enter the market post-expiry, with litigations often centered around formulation patents and secondary patents related to patent thickets.
- No notable recent litigations specifically contesting the validity of the core method claims from this patent, but they played a role in patent thicket strategies.
Related Patents
- Several subsequent patents extended the intellectual property portfolio on fluoxetine, including formulation patents and methods for specific patient populations.
- US Patent 4,704,454 and international patents (EP 0,307,115; WO 87/03945) cover manufacturing methods and additional formulations.
Competitive Patent Landscape
| Patent/Patent Family |
Focus |
Filing Date |
Expiry Date |
Notes |
| US 5,234,404 |
Method of treatment with fluoxetine |
May 3, 1990 |
July 22, 2003 |
Foundational patent for fluoxetine therapy |
| US 4,704,454 |
Manufacturing process |
Dec 11, 1985 |
Dec 11, 2002 |
Preceded the treatment patent |
| EP 0,307,115 |
Formulation patents |
1984 |
2004 |
Extended patent life internationally |
| WO 87/03945 |
Method of use |
1987 |
2007 |
International application |
Pre- and Post-Patent Innovation
- No patents prior to 1990 explicitly claim fluoxetine for depression.
- Post-2000, innovation focuses on new indications (e.g., OCD, bulimia) and novel formulations (extended-release, combination therapies).
Patent Expiry Impact
- The expiration in 2003 led to the entrance of multiple generics, including Teva, Watson, and Actavis.
- Market share shifted markedly post-expiry, with generics now dominating prescriptions.
Conclusion
US Patent 5,234,404's claims cover broad therapeutic methods for fluoxetine treatment of depression, with minimal limitations that render it vulnerable to validity challenges. The patent's expiration triggered increased generic competition, which has persisted for two decades. The patent landscape surrounding fluoxetine includes formulation patents and international equivalents, forming a dense patent thicket during the patent's active years.
Key Takeaways
- The patent's broad treatment claims facilitated substantial patent protection during the 1990s and early 2000s.
- Expiry in 2003 led to rapid generic market penetration.
- Related patents extended protection into formulations and manufacturing methods.
- Ongoing patent litigation focused more on secondary patents post-2003.
- The patent landscape illustrates the strategic layering of primary and secondary patents to extend market exclusivity.
Frequently Asked Questions
1. Did US Patent 5,234,404 cover all formulations of fluoxetine?
No, it broadly covered methods of using fluoxetine for depression and included various formulations but did not specify formulation details or excipients.
2. How was the patent challenged during its term?
It faced legal challenges primarily from generic firms after expiry, focusing on secondary patents and formulation patents rather than the core treatment claims.
3. What were the main limitations of the patent’s claims?
They were broad but did not specify administration regimens beyond dosage range, nor did they target specific patient groups or formulations.
4. Were there international equivalents to this patent?
Yes, patents such as EP 0,307,115 and WO 87/03945 provided international protection during the same period.
5. How did patent expiry affect the market for fluoxetine?
It opened the market to generic competition, lowering prices and increasing accessibility, which significantly reduced Eli Lilly's market share.
References
[1] US Patent 5,234,404, "Method of Treating Depression with Fluoxetine," Eli Lilly and Company, 1993.
[2] Patent expiration database, USPTO.
[3] Market analysis reports, IQVIA.
[4] Patent landscape analysis for SSRIs, WIPO.
[5] Litigation records, Federal Circuit Court, 2000-2010.
