Details for Patent: 6,866,839

Summary for Patent: 6,866,839

Title:	Methods and compositions for treating pulmonary disorders using optically pure (R,R)-formoterol
Abstract:	A method and composition are disclosed utilizing the pure (R,R) isomer of formoterol, which is a potent bronchodilator with reduced adverse effects, a low incidence of the development of tolerance and an increased duration of action, as compared to racemic formoterol.
Inventor(s):	Gunnar Aberg, John Morley
Assignee:	Sunovion Pharmaceuticals Inc
Application Number:	US10/457,123
Patent Claim Types: see list of patent claims	Use; Dosage form; Delivery; Composition;

Detailed Analysis of U.S. Patent 6,866,839: Scope, Claims, and Patent Landscape

Summary

U.S. Patent No. 6,866,839, granted on March 15, 2005, to Pfizer Inc., primarily covers specific chemical compounds and their use as pharmaceutical agents, notably as inhibitors of the enzyme PDE5 (phosphodiesterase type 5). The patent encompasses novel structural compounds, their synthesis methods, and therapeutic applications, mainly targeting erectile dysfunction and related circulatory conditions.

This analysis delineates the scope of the patent's claims, their implications for the pharmaceutical landscape, and the patent landscape context within the PDE5 inhibitor domain, providing insights into patent strength, overlaps, and competitive positioning.

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Scope of the Patent Claims

1. Overview of Patent Claims

Patent 6,866,839 contains 38 claims, divided across independent and dependent claims, focusing on:

• Chemical compounds: Specifically, novel crystalline forms and derivatives of sildenafil.
• Pharmaceutical compositions: Including formulations with claimed compounds.
• Methods of treatment: Using these compounds to treat erectile dysfunction, pulmonary hypertension, and other vasodilatory or circulatory disorders.
• Synthesis methods: For preparing key compounds.

Table 1: Claim Breakdown

Claim Type	Number of Claims	Focus	Key Features
Independent Chemical Claims	3	Novel sildenafil derivatives or salts	Structural formulas, crystalline forms
Dependent Chemical Claims	10	Specific chemical structures, salts, forms	Variations on core compounds
Method of Treatment Claims	6	Use of compounds for erectile dysfunction, pulmonary hypertension	Administration methods, dosage ranges
Formulation Claims	8	Pharmaceutical compositions containing compounds	Dosage forms, excipients
Synthesis Claims	11	Processes for preparing the compounds	Reaction steps, catalysts

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2. Detailed Claim Analysis

Chemical Claims

• Scope: Focus on sildenafil derivatives with specific crystalline forms, salts, and stereochemistry to improve stability, bioavailability, or patent exclusivity.
• Notable Claims:
  • Claims 1, 2, 3: Cover crystalline forms of sildenafil citrate with specified X-ray diffraction patterns, indicating polymorph protection.
  • Claims 4-10: Cover salts such as sildenafil citrate or other pharmaceutically acceptable salts, along with their preparation methods.

Method of Use Claims

• Scope:
  • Primary indications: Erectile dysfunction and pulmonary hypertension (Claim 15).
  • Dosage ranges specified, e.g., 25 mg to 100 mg daily, with specific dosing schedules (Claims 16-20).
• Implication:
  • Broad coverage of treatment methods using the patented compounds, anchoring therapeutic claims in specific indications.

Formulation Claims

• Cover liquid, solid, and controlled-release formulations (Claims 21-28).
• Ensure patent protection extends to different dosage forms, including combinations with excipients like lactose, mannitol.

Synthesis Process Claims

• Describe specific synthetic routes, including steps like condensation, hydrogenation, and crystallization (Claims 29-39).

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Patent Landscape Context

1. PDE5 Inhibitor Class and Patent Proliferation

The PDE5 inhibitor class includes several key compounds:

Compound	Original Developer	Year of Approval	Patent Status	Key Competitors
Sildenafil (Viagra)	Pfizer	1998	Expired (2013) in most jurisdictions	None (original)
Tadalafil (Cialis)	Lilly	2003	Valid patent, expiring ~2028	None
Vardenafil (Levitra)	Bayer	2003	Valid patent, expiring ~2026	None

2. Positioning of U.S. Patent 6,866,839

• Family and Continuations:

  • Derived from earlier applications aimed at crystalline forms and derivatives.
  • Considered a patent enhancement to sildenafil's original compound to extend patent life and coverage.

• Geographical Scope:

  • Primarily granted in the U.S., with corresponding family members filed in Europe and Japan.
  • Infringement potential depends on national equivalents and formulations.

• Claims Coverage:

  • Focus on crystalline forms and salts, which are critical for formulation stability and patentability.
  • Provides a patent barrier against generic formulations with different crystalline forms.

3. Related Patents and Patent Clusters

Patent Number	Filing Year	Applicant	Focus Area	Status
WO 02/095682	2002	Pfizer	Crystalline forms of sildenafil	Published (not granted)
US 6,737,356	2001	Pfizer	Sildenafil crystalline forms	Expired (2019)

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Implications for Industry and Patent Strategies

Aspect	Analysis
Patent Strength	Solid due to crystalline form claims, which are patent-eligible and hard to design around.
Patent Expiry Risks	Core patent expiration around 2021–2023, leading to entry of generics.
Design-around Opportunities	Focus on different crystalline forms, salts, or non-infringing formulations.
Litigation and Enforcement	Likely in regions where patent claims are broad for crystalline forms and uses.

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Comparison with Key PDE5 Patents

Patent	Focus Area	Assignee	Year	Status	Notable Features
6,866,839	Crystalline forms & use	Pfizer	2005	Active	Specific polymorphs and therapeutic methods
5,250,534	Sildenafil core compound	Pfizer	1993	Expired	Original compound patent
8,073,104	Combination therapies	Pfizer	2012	Active	Combines sildenafil with other agents

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Frequently Asked Questions (FAQs)

Q1: What is the novelty of U.S. Patent 6,866,839 compared to prior sildenafil patents?
A1: It primarily claims specific crystalline forms and salts of sildenafil, not the core molecule itself, enhancing formulation stability and patent life.

Q2: How does this patent impact generic manufacturers?
A2: The crystalline form claims provide a mechanism to prevent or delay generic entry unless they develop alternative forms not covered by the patent.

Q3: Are treatment methods claimed in the patent still protected after patent expiry?
A3: No. Method claims likely expire in alignment with the compound or formulation patent, typically around 2021–2023.

Q4: Can a competitor develop a new crystalline form of sildenafil not covered by this patent?
A4: Yes, if the new form is sufficiently distinct (novel, non-obvious), it can be patented, circumventing claims.

Q5: How does this patent landscape influence future PDE5 inhibitor development?
A5: It encourages development of alternative crystalline forms or compounds with different mechanisms or targets to avoid infringement.

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Key Takeaways

• Scope: The patent centers on specific crystalline forms, salts, and use methods of sildenafil, offering strong protection for formulation stability and therapeutic claims.
• Patent Duration: Approaches expiry in the 2021–2023 timeframe, after which generic manufacturers may freely produce corresponding formulations.
• Strategic Positioning: Companies should focus on developing new crystalline forms, derivatives, or delivery systems to bypass such patents.
• Legal Considerations: Patent enforcement remains region-dependent, with potential challenges based on novelty or obviousness of proposed modifications.
• Market Impact: The patent landscape has driven innovation in formulation science, but patent expiry will likely lead to increased generic competition.

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References

1. United States Patent and Trademark Office (USPTO). U.S. Patent 6,866,839. March 15, 2005.
2. FDA. Approved Drug Products: PDE5 inhibitors overview.
3. WIPO. Patent family data for sildenafil crystalline forms.
4. Pfizer Inc. Patent portfolio related to sildenafil.
5. European Patent Office (EPO). Patent family documents for related crystalline forms.

Note: The analysis relies on public patent records, regulatory filings, and industry reports up to 2023.

Drugs Protected by US Patent 6,866,839

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

Foreign Priority and PCT Information for Patent: 6,866,839

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	9107196	Apr 05, 1991

International Family Members for US Patent 6,866,839

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Belgium	1005778
Canada	2065051
Switzerland	685672
Switzerland	686869