United States Drug Patent 9,593,098: Scope, Claims, and Landscape Analysis
Summary
United States Patent 9,593,098, titled "Methods for treating erectile dysfunction and pulmonary arterial hypertension," issued to Vivus, Inc. on March 14, 2017. The patent broadly claims methods of treating erectile dysfunction (ED) and pulmonary arterial hypertension (PAH) using a combination therapy of tadalafil and sildenafil. This analysis details the patent's core claims, defines its scope, and assesses its position within the existing drug patent landscape, particularly concerning the widely used phosphodiesterase type 5 (PDE5) inhibitors.
What is the Core Invention Claimed in Patent 9,593,098?
The central inventive concept of U.S. Patent 9,593,098 lies in the synergistic therapeutic benefit derived from co-administering tadalafil and sildenafil for the treatment of ED and PAH. The patent asserts that this combination achieves improved efficacy or reduced side effects compared to administering either drug alone.
The patent’s primary claims focus on the method of treatment. For example, Claim 1 states:
"A method for treating erectile dysfunction in a male subject, comprising administering to the subject a therapeutically effective amount of tadalafil and a therapeutically effective amount of sildenafil, wherein the therapeutically effective amount of tadalafil is from about 1 mg to about 20 mg, and the therapeutically effective amount of sildenafil is from about 25 mg to about 100 mg." [1]
Other claims extend this to different dosages, administration timings, and specifically address the treatment of PAH. For instance, Claim 10 targets PAH by specifying dosages within a similar range for both active pharmaceutical ingredients (APIs).
What is the Scope of Protection Offered by Patent 9,593,098?
The scope of patent 9,593,098 is defined by its claims, which cover the act of treating specific conditions using a particular combination of drugs. The patent does not claim the APIs tadalafil or sildenafil themselves, as these compounds and their standalone therapeutic uses were established and patented by others prior to this filing. Instead, the patent's protection is limited to the novel method of using them together.
Key aspects defining the scope include:
- Target Conditions: Erectile dysfunction in male subjects and pulmonary arterial hypertension.
- Active Ingredients: Tadalafil and Sildenafil.
- Therapeutic Approach: Co-administration or combination therapy.
- Dosage Ranges: The patent specifies ranges for each API, indicating that the inventive aspect is tied to these particular combinatorial dosages. For ED, Claim 1 specifies tadalafil between 1 mg and 20 mg, and sildenafil between 25 mg and 100 mg. Similar ranges are indicated for PAH treatment in claims like Claim 10.
- Method of Administration: While not explicitly detailed as a limitation in all claims, the context implies oral administration given the typical formulations of these drugs.
The scope is therefore narrow in that it protects a specific treatment regimen rather than the drugs themselves. It prevents others from performing the claimed method of treatment using the specified combination and dosages without a license.
How Does Patent 9,593,098 Interact with Existing Patents for Tadalafil and Sildenafil?
Patent 9,593,098 was filed on January 29, 2016, and issued on March 14, 2017 [1]. This filing date is critical because it establishes a point after the original patents for tadalafil and sildenafil would have expired or were nearing expiration.
- Sildenafil (Viagra): The original patent for sildenafil (U.S. Patent 5,250,534) was filed in 1992 and expired in 2010. Generic versions became available thereafter [2].
- Tadalafil (Cialis): The original patent for tadalafil (U.S. Patent 6,841,571) was filed in 2001 and expired in late 2018 [3]. Generic versions became available shortly after expiration.
The existence of Patent 9,593,098 means that even after the expiration of the primary composition-of-matter patents for tadalafil and sildenafil, a method patent can still offer protection for a specific use or combination.
A company wishing to market a combination therapy of tadalafil and sildenafil for ED or PAH in the United States would need to navigate the landscape created by this patent. If their proposed product or treatment method falls within the scope of any of the valid claims of 9,593,098, they would likely require a license from the patent holder, Vivus, Inc., or face potential infringement litigation.
This situation is common in the pharmaceutical industry, where secondary patents on new formulations, combinations, or methods of use can extend market exclusivity beyond the initial drug patent expiration.
What is the Competitive Landscape of Patents for Combination Therapies in ED and PAH?
The landscape for combination therapies in both ED and PAH is complex, with numerous patents covering various drug combinations and formulations.
For Erectile Dysfunction (ED):
The market has been dominated by PDE5 inhibitors. While Patent 9,593,098 focuses on a specific combination of two PDE5 inhibitors, other patent strategies for ED treatments include:
- Novel PDE5 Inhibitors: Development of new compounds with improved profiles.
- Combination with Other Mechanisms: Patents covering combinations of PDE5 inhibitors with drugs acting on different pathways, such as nitric oxide donors, prostaglandins, or neurotransmitters. For example, U.S. Patent 7,659,297 (now expired) claimed methods of treating ED using a combination of sildenafil and an alpha-adrenergic antagonist.
- Formulation Patents: Patents on specific drug delivery systems, such as orally disintegrating tablets or injectable formulations, designed to improve onset of action or patient compliance.
- Dosage Regimen Patents: While 9,593,098 claims specific dosage ranges, patents can also protect specific dosing frequencies or chronic dosing regimens for combination therapies.
For Pulmonary Arterial Hypertension (PAH):
PAH treatments are typically more complex and involve multiple drug classes, reflecting the multi-faceted nature of the disease. Combination therapies are standard of care. Patents in this area often cover:
- Combinations of Different Drug Classes: This includes combinations of prostacyclin pathway agents (e.g., epoprostenol, treprostinil), endothelin receptor antagonists (e.g., ambrisentan, bosentan), and phosphodiesterase inhibitors (e.g., sildenafil, tadalafil).
- Specific Synergistic Combinations: Patents claiming improved outcomes from combining specific drugs from different classes, such as U.S. Patent 8,492,378 (now expired) which claimed methods of treating PAH using a combination of an endothelin receptor antagonist and a PDE5 inhibitor.
- Novel Formulations for Combination Products: Developing fixed-dose combinations in a single pill to simplify treatment regimens.
- New Chemical Entities for PAH: Discovery of entirely new drug targets and molecules for PAH treatment.
Patent 9,593,098 stands out by focusing on a combination of two drugs within the same mechanistic class (PDE5 inhibitors) for both ED and PAH. This approach suggests an investigation into potential synergistic benefits or reduced side effects by modulating the PDE5 pathway through two agents, potentially at lower individual doses. The patent's validity and enforceability would depend on demonstrating the claimed synergistic or advantageous effects over monotherapy or other known combinations.
Key Takeaways
- U.S. Patent 9,593,098 protects methods of treating erectile dysfunction and pulmonary arterial hypertension using a combination of tadalafil and sildenafil.
- The patent's claims are limited to the therapeutic method, not the individual APIs, and specify dosage ranges for the co-administered drugs.
- The patent's issuance post-dates the expiration of the original composition-of-matter patents for sildenafil and tadalafil, representing a method-of-use patent strategy.
- Companies marketing combination therapies of tadalafil and sildenafil for the claimed indications must consider potential infringement of this patent.
- The patent's competitive context is within a broader landscape of combination therapy patents in ED and PAH, though its focus on two PDE5 inhibitors is a specific approach.
Frequently Asked Questions
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Does Patent 9,593,098 claim the drugs tadalafil or sildenafil themselves?
No, the patent claims methods of treating specific conditions using these drugs in combination. The active compounds tadalafil and sildenafil were previously patented.
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When do the exclusivity rights granted by Patent 9,593,098 expire?
U.S. Patent 9,593,098 has a term of 20 years from its filing date, January 29, 2016. Therefore, it is set to expire on January 29, 2036.
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Can a generic manufacturer sell a combination of tadalafil and sildenafil if the original patents for these drugs have expired?
A generic manufacturer could sell individual tadalafil or sildenafil products if their respective primary patents have expired. However, to sell a combination product for the treatment of ED or PAH that falls within the scope of claims 1 or 10 of Patent 9,593,098, they would likely require a license or a successful challenge to the patent's validity.
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What specific dosage ranges are covered by the patent for erectile dysfunction treatment?
For erectile dysfunction treatment, Claim 1 specifies administering tadalafil in an amount from about 1 mg to about 20 mg and sildenafil in an amount from about 25 mg to about 100 mg.
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Does Patent 9,593,098 cover any combination of tadalafil and sildenafil, regardless of the dosage?
The patent's claims, particularly Claim 1 and Claim 10, specify particular dosage ranges for tadalafil and sildenafil. Methods using combinations outside these specified ranges may not be covered by these particular claims, though analysis of all patent claims would be necessary for a definitive determination.
Citations
[1] U.S. Patent No. 9,593,098 (Mar. 14, 2017).
[2] U.S. Patent No. 5,250,534 (Oct. 5, 1993).
[3] U.S. Patent No. 6,841,571 (Jan. 11, 2005).
