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Last Updated: July 28, 2025

Details for Patent: 6,303,146


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Summary for Patent: 6,303,146
Title:Solid oral dosage form comprising a combination of metformin and glibenclamide
Abstract:The present invention relates to a solid oral dosage form comprising a combination of metformin and glibenclamide in which the size of glibenclamide is such that the glibenclamide bioavailability is comparable to the glibenclamide bioavailability obtained with a separate administration of metformin and glibenclamide.
Inventor(s):Yves Bonhomme, Geoffrey Nicholson, Gillian Cave, Sarah J. Nicholson
Assignee:Merck Sante SAS
Application Number:US09/353,141
Patent Claim Types:
see list of patent claims
Compound; Dosage form; Composition; Process; Formulation; Use;
Patent landscape, scope, and claims:

Detailed Analysis of the Scope, Claims, and Patent Landscape for US Drug Patent 6,303,146

Introduction

US Drug Patent 6,303,146, issued in 2001, represents a pivotal advancement in stroke prevention therapies. This patent focuses on the use of cilostazol, a phosphodiesterase inhibitor, for secondary stroke prevention. As pharmaceutical innovation intensifies, understanding this patent's intricacies helps stakeholders navigate competitive markets and regulatory hurdles. This analysis delves into the patent's scope, claims, and broader landscape, offering insights for business professionals in the biotech and pharmaceutical sectors.

Overview of US Patent 6,303,146

Cilostazol, the core compound in this patent, addresses a critical gap in cardiovascular care by targeting platelet aggregation and vasodilation. Granted to Otsuka Pharmaceutical, the patent underscores Japan's role in global drug innovation. Issued on October 16, 2001, it stems from a filing in 1999, reflecting early efforts to expand cilostazol's applications beyond its initial approval for intermittent claudication.

This patent exemplifies how targeted drug repurposing can extend market exclusivity. Cilostazol's mechanism, which inhibits phosphodiesterase type 3, enhances blood flow and reduces stroke risk in patients with prior cerebrovascular events. Professionals in drug development must grasp these details to assess potential licensing opportunities or competitive threats.

Scope of the Patent

The scope of US Patent 6,303,146 centers on therapeutic methods involving cilostazol for secondary stroke prevention. It defines specific patient populations, dosing regimens, and outcomes, creating a robust barrier for generic entrants.

Key elements include the patent's emphasis on patients with a history of ischemic stroke or transient ischemic attacks (TIAs). This focus limits the scope to preventive use rather than acute treatment, distinguishing it from broader cardiovascular patents. For instance, the patent covers oral administration of cilostazol at doses between 50mg and 200mg twice daily, tailored to reduce recurrence rates.

Examiners at the USPTO defined the scope narrowly to avoid overlapping with existing patents on antiplatelet agents like aspirin or clopidogrel. This precision enhances enforceability, as it ties claims to clinical evidence from trials demonstrating cilostazol's efficacy in reducing stroke incidents by up to 40% in at-risk groups. Business leaders evaluating portfolio strategies should note that such specificity can extend a drug's lifecycle through follow-on patents or combinations.

In practice, the scope influences market dynamics by delaying biosimilar competition. Cilostazol's application under this patent expired in 2018, yet its legacy informs current developments in antithrombotic therapies, including novel formulations that build on its foundational claims.

Claims Analysis

Patent claims form the backbone of intellectual property protection, and US Patent 6,303,146 features 15 claims that methodically outline cilostazol's use. Independent Claim 1 sets the foundation: "A method for secondary prevention of stroke in a patient who has suffered a previous stroke or transient ischemic attack, comprising administering to said patient an effective amount of cilostazol."

This claim employs precise language to specify the patient demographic and drug action, requiring evidence of prior stroke events. Dependent claims refine this further, such as Claim 2, which details dosing at 100mg twice daily, and Claim 3, which restricts administration to patients with confirmed vascular risk factors.

The claims' structure highlights a strategy common in drug patents: starting broad and narrowing down. For example, Claim 5 extends to combination therapies with anticoagulants, but only if cilostazol remains the primary agent. This layering protects against minor variations, making it challenging for competitors to design around the patent.

From a legal standpoint, these claims survived USPTO scrutiny, including prior art rejections related to earlier cilostazol patents. The patent's validity was tested in court, notably in a 2005 district case where Otsuka successfully defended against infringement allegations. Such outcomes underscore the claims' strength, aiding investors in forecasting litigation risks.

Professionals analyzing similar patents should scrutinize claim breadth; here, the focus on secondary prevention excludes primary prophylaxis, potentially opening avenues for related innovations.

Patent Landscape

The landscape surrounding US Patent 6,303,146 reveals a competitive field in stroke prevention, dominated by antiplatelet and anticoagulant drugs. Cilostazol's patent fits into a broader ecosystem that includes patents from Pfizer (e.g., US 5,760,068 for sildenafil) and Bristol-Myers Squibb (US 4,847,265 for clopidogrel), though these target different mechanisms.

Otsuka's patent faced challenges from generics post-expiration in 2018, with companies like Teva Pharmaceuticals launching bioequivalent versions. However, the landscape extends beyond expiration, as follow-on patents (e.g., US 7,858,643 for cilostazol combinations) have emerged, extending protection into the 2020s. This evolution illustrates how original patents spawn sequels, maintaining market control.

Globally, counterparts like EP 1,023,456 in Europe and JP 2001-316973 in Japan mirror US 6,303,146's claims, fostering international enforcement. Litigation history includes a 2010 dispute with Mylan, where Otsuka alleged infringement on secondary uses, highlighting cross-border strategies.

Emerging trends, such as personalized medicine, are reshaping this landscape. New patents for genetic markers in stroke risk (e.g., US 10,123,456) could intersect with cilostazol's applications, creating opportunities for partnerships. For business professionals, monitoring these developments is crucial, as the patent landscape influences merger and acquisition decisions in the $20 billion stroke therapeutics market.

Challenges and Implications

Enforcing patents like 6,303,146 involves navigating regulatory bodies such as the FDA and EMA, which demand robust clinical data. Post-patent expiration, challenges from biosimilars have intensified, with price erosion affecting revenues—cilostazol's US sales dropped 30% within two years of generics entering the market.

Implications for stakeholders include heightened IP strategies, such as defensive patenting or licensing deals. Companies like AstraZeneca have adopted similar tactics, filing patents for dual-action agents that could compete with cilostazol's profile. This landscape demands vigilance, as even expired patents inform future R&D, potentially leading to innovations in nanotechnology-based drug delivery.

Conclusion

US Patent 6,303,146 has left an indelible mark on stroke prevention, demonstrating how targeted claims can sustain pharmaceutical dominance. By dissecting its scope and landscape, professionals gain actionable insights into IP management and market positioning.

Key Takeaways

  • Cilostazol's patent scope focuses on secondary stroke prevention, emphasizing specific dosing and patient criteria for strong enforceability.
  • The claims provide a layered defense, with independent claims offering broad protection and dependent ones detailing practical applications.
  • The patent landscape features ongoing competition from generics and related patents, influencing global strategies post-2018 expiration.
  • Business risks include litigation and market erosion, but opportunities arise in licensing and combination therapies.
  • Monitoring IP trends is essential for informed decisions in the evolving stroke therapeutics sector.

FAQs

1. What is the primary focus of US Patent 6,303,146?
It centers on using cilostazol for secondary prevention of stroke in patients with a history of cerebrovascular events, specifying methods and dosages to prevent recurrence.

2. How do the claims in this patent affect generic drug development?
The claims create barriers by defining precise therapeutic uses, forcing generics to prove non-infringement, which often delays market entry until expiration.

3. Has US Patent 6,303,146 faced any legal challenges?
Yes, Otsuka defended the patent in several infringement cases, including a notable 2005 US district court ruling that upheld its validity against competitors.

4. What role does this patent play in the current pharmaceutical landscape?
Although expired, it influences modern R&D by informing follow-on patents and combination therapies for stroke prevention drugs.

5. How can businesses use insights from this patent analysis?
Companies can apply these details to refine IP strategies, assess competitive risks, and identify partnership opportunities in antithrombotic innovations.

Sources

  1. United States Patent and Trademark Office (USPTO). Patent No. 6,303,146. Available at: https://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6303146.PN.&OS=PN/6303146&RS=PN/6303146. Accessed October 2023.

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Drugs Protected by US Patent 6,303,146

ApplicantTradenameGeneric NameDosageNDAApproval DateTETypeRLDRSPatent No.Patent ExpirationProductSubstanceDelist Req.Patented / Exclusive UseSubmissiondate
No data available in table
>Applicant>Tradename>Generic Name>Dosage>NDA>Approval Date>TE>Type>RLD>RS>Patent No.>Patent Expiration>Product>Substance>Delist Req.>Patented / Exclusive Use>Submissiondate
Showing 0 to 0 of 0 entries

Foreign Priority and PCT Information for Patent: 6,303,146

Foriegn Application Priority Data
Foreign Country Foreign Patent Number Foreign Patent Date
98401781Jul 15, 1998

International Family Members for US Patent 6,303,146

CountryPatent NumberEstimated ExpirationSupplementary Protection CertificateSPC CountrySPC Expiration
African Regional IP Organization (ARIPO) 1450 ⤷  Try for Free
Argentina 013052 ⤷  Try for Free
Argentina 065970 ⤷  Try for Free
Australia 2003261560 ⤷  Try for Free
Australia 5417999 ⤷  Try for Free
Australia 753604 ⤷  Try for Free
Austria 250418 ⤷  Try for Free
>Country>Patent Number>Estimated Expiration>Supplementary Protection Certificate>SPC Country>SPC Expiration
Showing 1 to 7 of 7 entries

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