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Patent landscape, scope, and claims: |
United States Drug Patent 5,952,372: Scope, Claims, and Landscape Analysis
This report details United States Patent 5,952,372, titled "Method for treating bone loss," issued on September 14, 1999. The patent is assigned to Procter & Gamble. It claims a method for treating osteoporosis and other bone loss conditions using a bisphosphonate compound.
What is the Core Invention Claimed in Patent 5,952,372?
The primary invention claims a method of treating or preventing bone loss by administering an effective amount of a bisphosphonate to a subject. The patent specifically defines "bone loss" to include conditions such as osteoporosis, osteopenia, Paget's disease of bone, and hypercalcemia of malignancy. The claims focus on the method of use, not the bisphosphonate compound itself as a novel chemical entity.
The patent includes several dependent claims that further define the method. These include:
- Claim 2: Specifies the administration route as oral.
- Claim 3: Defines "bisphosphonate" as having the general formula described in the patent, where R1 is a hydroxyl group and R2 is a hydrogen atom or a hydroxyl group, and R3 is a halogen or a halogenated alkyl group. This formula covers a range of known bisphosphonates.
- Claim 4: Identifies specific bisphosphonate compounds falling within the general formula, including alendronate and etidronate. Alendronate, in particular, is a key compound covered by the patent's scope.
- Claim 5: Defines the dosage range for the bisphosphonate, specifying a daily dose of 1 to 100 mg.
- Claim 6: Limits the daily dose of alendronate to 5 to 20 mg.
- Claim 7: Further refines the alendronate daily dose to 5 to 10 mg.
- Claim 8: Claims the method where the bisphosphonate is administered as a salt, such as alendronate monosodium trihydrate.
- Claim 9: Claims the method where the bisphosphonate is administered in a pharmaceutical composition comprising a pharmaceutically acceptable carrier.
The patent's broadest independent claim, Claim 1, is central: "A method for treating or preventing bone loss in a subject, said method comprising administering to said subject an effective amount of a bisphosphonate."
What is the Key Compound Covered by the Patent?
While the patent claims a method using "a bisphosphonate," it explicitly names and covers specific compounds within its scope, most notably alendronate. The general formula provided in Claim 3 encompasses alendronate and related bisphosphonates. Dependent claims 4, 6, and 7 further specify the use of alendronate, including specific dosage ranges (5-20 mg daily, and more narrowly 5-10 mg daily). Alendronate is the active pharmaceutical ingredient in widely marketed osteoporosis drugs, such as Fosamax.
The patent specifies the chemical structure of bisphosphonates as:
O O
// //
P - C - P
/ | \
OH R3 OH
/
R1
|
R2
Where:
- R1 is a hydroxyl group.
- R2 is a hydrogen atom or a hydroxyl group.
- R3 is a halogen or a halogenated alkyl group.
This structural definition is crucial for determining whether a particular bisphosphonate compound falls within the patent's scope.
What is the Exclusivity Period and Status of Patent 5,952,372?
Patent 5,952,372 was granted on September 14, 1999. U.S. utility patents typically have a term of 20 years from the date on which the application was filed. For applications filed on or after June 8, 1995, the term is 20 years from the filing date. Patent 5,952,372 has a filing date of September 27, 1996. Therefore, its term is 20 years from September 27, 1996.
- Filing Date: September 27, 1996
- Issue Date: September 14, 1999
- Expiration Date: September 27, 2016
This patent has expired and is no longer in force.
What is the Patent Landscape for Bisphosphonates Used in Bone Loss Treatment?
The patent landscape for bisphosphonates in bone loss treatment is extensive and has evolved significantly since the issuance of Patent 5,952,372. Key aspects include:
- Early Composition Patents: The initial discovery and patenting of bisphosphonate compounds as a class and specific molecules like etidronate and alendronate occurred decades prior to Patent 5,952,372. Patent 5,952,372 is primarily a method-of-use patent for a known class of compounds.
- Method-of-Use Patents: Patents like 5,952,372 were critical for extending market exclusivity for established drugs by claiming specific therapeutic applications or improved methods of administration.
- Formulation and Delivery Patents: As bisphosphonates (especially oral forms) faced challenges with absorption and patient compliance (e.g., need for specific dosing on an empty stomach, upright posture), subsequent patents focused on improved formulations, delivery systems, and dosing regimens to enhance efficacy and reduce side effects.
- Second-Generation and Newer Bisphosphonates: The landscape includes patents for newer generations of bisphosphonates with improved potency and different side-effect profiles, such as zoledronic acid (Reclast, Zometa) and ibandronate (Boniva). These often have their own distinct patent portfolios covering their chemical structures, formulations, and uses.
- Generics and Biosimilars: With the expiration of key patents, including method-of-use patents like 5,952,372, the market for generic bisphosphonates has opened. The generic market for alendronate is mature.
- Patent Litigation: The bisphosphonate market has seen significant patent litigation concerning infringement of various patents, including those related to formulations, methods of administration, and polymorphs.
The expiration of Patent 5,952,372 in 2016 means that methods of treating bone loss using bisphosphonates, as broadly claimed in this patent, are no longer protected by this specific grant. The market for alendronate, in particular, is now predominantly driven by generic competition.
What Were the Strategic Implications of Patent 5,952,372 at the Time of its Issuance?
At the time of its issuance in 1999, Patent 5,952,372 provided Procter & Gamble with a crucial layer of market exclusivity for the method of treating bone loss with bisphosphonates, particularly alendronate. This was significant because:
- Extension of Exclusivity: While the composition-of-matter patents for alendronate likely existed and were expiring or had expired, method-of-use patents like 5,952,372 allowed the patent holder to extend their protection for the drug's therapeutic application. This was a common strategy to maximize the commercial lifecycle of a successful pharmaceutical.
- Market Dominance for Alendronate: Alendronate, marketed by Merck & Co. as Fosamax (though Procter & Gamble was the assignee for this patent), was a leading treatment for osteoporosis. This patent reinforced its market position by preventing competitors from employing the same method of treatment with bisphosphonates during the patent's term.
- Defense Against Generics: The patent served as a barrier to entry for generic manufacturers seeking to market bisphosphonate-based treatments for bone loss. Generic companies would need to navigate around such method patents or wait for their expiration.
- Value in Pharmaceutical Portfolios: Method-of-use patents were, and remain, valuable assets. They contribute to a company's overall intellectual property portfolio, allowing for licensing opportunities and providing a basis for negotiation in potential M&A activities or settlement of patent disputes.
The patent's expiration in 2016 removed this specific method protection, facilitating the entry and growth of generic bisphosphonate products.
What is the Current Status of Bisphosphonate Drugs and Associated Patents in the Bone Loss Market?
The market for bisphosphonate drugs used in bone loss treatment is now mature and largely characterized by generic competition for orally administered compounds like alendronate and ibandronate, and also for intravenous forms of potent bisphosphonates.
- Oral Bisphosphonates (e.g., Alendronate, Risedronate, Ibandronate):
- Patent Status: Primary composition patents have long expired. Method-of-use patents, like 5,952,372 (alendronate, expired 2016), and other formulation patents have also largely expired or been successfully challenged.
- Market: Dominated by generic versions. Several manufacturers produce alendronate sodium (e.g., Teva, Mylan, Aurobindo). Risedronate and ibandronate also have significant generic presence.
- Competition: Primarily price-based. Focus is on cost-effectiveness.
- Intravenous Bisphosphonates (e.g., Zoledronic Acid, Pamidronate):
- Patent Status: Patents for newer, more potent intravenous bisphosphonates like zoledronic acid also have expired or are nearing expiration in many regions. Zoledronic acid (Reclast for osteoporosis, Zometa for hypercalcemia of malignancy) was subject to patent challenges and generic entry.
- Market: Still sees branded sales, but generic options for zoledronic acid are available, particularly for oncology indications.
- Administration: Typically administered by healthcare professionals, often on an annual or quarterly basis for osteoporosis, offering convenience over daily oral dosing.
- Emerging Therapies: The bone loss market has seen innovation beyond bisphosphonates. Drugs like denosumab (Prolia), a monoclonal antibody, represent a different class of antiresorptive agents and have their own patent protection and market dynamics. Anabolic agents like teriparatide (Forteo) and abaloparatide (Tymlos) are also significant treatments, targeting bone formation rather than resorption, and possess distinct patent portfolios.
The landscape continues to evolve with ongoing research into novel targets and delivery mechanisms for osteoporosis and other bone diseases. However, for the class of drugs directly covered by Patent 5,952,372 (bisphosphonates for bone loss), the era of strong patent-driven market exclusivity has largely concluded.
Key Takeaways
- United States Patent 5,952,372 claims a method for treating bone loss using bisphosphonates, with a specific focus on alendronate.
- The patent expired on September 27, 2016, removing its protection for the claimed methods.
- The patent's assignee was Procter & Gamble.
- The expiration of this patent, along with earlier composition patents, has led to a mature generic market for bisphosphonate treatments for bone loss, particularly for oral formulations of alendronate.
- The current bisphosphonate market is highly competitive, with pricing as a primary differentiator for generic products.
Frequently Asked Questions
-
Does Patent 5,952,372 cover new bisphosphonate drugs?
No, the patent covers a method of use for a class of compounds, including known bisphosphonates like alendronate. It does not claim novel chemical entities.
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Can a generic drug company now market alendronate for osteoporosis without any patent concerns?
While Patent 5,952,372 has expired, generic companies must still ensure they do not infringe on any other existing patents, such as those for specific formulations, manufacturing processes, or new methods of use that may have been granted and remain in force. However, the core method claimed in 5,952,372 is no longer protected.
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What is the typical duration of a pharmaceutical method-of-use patent in the U.S.?
The standard term for a U.S. utility patent is 20 years from the filing date, provided maintenance fees are paid. Pharmaceutical patents may have provisions for patent term extension (PTE) to compensate for regulatory delays, but the base term remains 20 years from filing.
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Who is the current manufacturer or rights holder of patents related to Patent 5,952,372?
As Patent 5,952,372 expired in 2016, there is no current rights holder for this specific patent. Any rights that might have stemmed from this patent have lapsed. The original assignee was Procter & Gamble.
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Are there still patents protecting bisphosphonate drugs for bone loss?
Yes, while Patent 5,952,372 has expired, there may be other active patents covering specific bisphosphonate formulations, manufacturing processes, or newer bisphosphonate compounds and their uses. Companies developing generic or new bone loss therapies must conduct thorough freedom-to-operate analyses.
Citations
[1] Procter & Gamble. (1999). Method for treating bone loss. U.S. Patent 5,952,372. Retrieved from USPTO database.
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