United States Patent 5,006,528: A Detailed Analysis of Scope, Claims, and Patent Landscape
Introduction
The United States Patent 5,006,528, assigned to Otsuka Pharmaceutical Co., Ltd., is a pivotal patent in the pharmaceutical industry, particularly for the drug aripiprazole, marketed as Abilify. This patent has been at the center of several legal battles involving generic drug manufacturers. Here, we delve into the scope, claims, and the broader patent landscape surrounding this patent.
Background and History
The '528 patent was filed on October 20, 1989, and issued on April 9, 1991. It has a foreign priority date of October 31, 1988. The patent includes a five-year patent term extension and a six-month period of pediatric exclusivity, which extended its exclusivity until April 20, 2015[1].
Chemical Structure and Composition
The patent describes a novel carbostyril derivative, specifically aripiprazole. Aripiprazole features a butoxy linker consisting of four methylene units, a piperazine ring, and a phenyl ring that is 2,3-dichloro substituted. This specific chemical structure is crucial for its pharmacological properties as an atypical antipsychotic agent[1][4].
Claims of the Patent
The '528 patent includes several key claims:
- Claim 12: This claim specifies aripiprazole using its chemical name.
- Claim 16: This claim covers a pharmaceutical composition for treating schizophrenia containing a carbostyril compound as the active ingredient.
- Claim 17: This claim is a subset of Claim 16, specifically identifying the carbostyril compound as aripiprazole.
- Claim 23: Added during re-examination, this claim describes a method of treating schizophrenia by administering a pharmaceutical composition containing aripiprazole as the active ingredient[1].
Prior Art and Related Patents
The '528 patent is related to an earlier patent, U.S. Patent 4,734,416 (the '416 patent), which is considered prior art. The '416 patent discloses a broad genus of carbostyril derivatives, including the "unsubstituted butoxy" compound, which has a similar structure but lacks the specific substitutions present in aripiprazole[1].
Patent Infringement and Legal Challenges
Generic drug manufacturers, such as Apotex, Teva, and others, submitted Abbreviated New Drug Applications (ANDAs) to the FDA for approval to manufacture, use, or sell generic aripiprazole products. Otsuka Pharmaceutical Co., Ltd. brought actions against these manufacturers for patent infringement, asserting that their ANDA filings constituted literal infringement of claims 12, 17, and 23 of the '528 patent. The defendants argued that the claims were invalid due to obviousness and obviousness-type double patenting[1][2].
Court Decisions and Appeals
The United States District Court for the District of New Jersey sustained the validity of the asserted claims under 35 U.S.C. § 103 and the doctrine of nonstatutory double patenting. The defendants appealed, but the decision was affirmed. The court also rejected the defendants' inequitable conduct defense and counterclaim[1].
Patent Scope and Quality
The scope of the '528 patent is a subject of interest in broader discussions about patent quality. Metrics such as independent claim length and independent claim count can be used to measure patent scope. The examination process for the '528 patent, like many others, tends to narrow the scope of patent claims, ensuring clarity and validity[3].
Related Patents and the Broader Patent Landscape
The '528 patent is part of a larger portfolio of patents covering aripiprazole. Other relevant patents include U.S. Patent Nos. 7,053,092, 8,017,615, 8,580,796, 8,642,600, 8,642,760, and 8,759,350. These patents cover various aspects of aripiprazole, including methods of treatment and specific formulations[2][5].
Impact on Generic Drug Manufacturers
The '528 patent and related patents have significant implications for generic drug manufacturers. Otsuka's assertions of direct infringement, contributory infringement, and induced infringement under 35 U.S.C. §§ 271(a)-(c) have led to extensive legal battles. The statutory basis for these claims, particularly under 35 U.S.C. § 271(e)(2)(A), requires that the ANDA filer seeks approval for a drug claimed in a patent or the use of which is claimed in a patent prior to the patent's expiration[2].
Conclusion and Key Takeaways
- Patent Scope and Claims: The '528 patent specifically claims aripiprazole and its use in treating schizophrenia, with detailed chemical structures and compositions.
- Legal Challenges: The patent has been subject to numerous legal challenges from generic drug manufacturers, with Otsuka successfully defending its validity.
- Related Patents: The '528 patent is part of a broader portfolio of patents covering various aspects of aripiprazole.
- Impact on Generic Manufacturers: The patent has significant implications for generic drug manufacturers, affecting their ability to market generic versions of aripiprazole.
Key Takeaways
- The '528 patent is crucial for Otsuka's exclusivity over aripiprazole.
- The patent's claims are specific and have been upheld against challenges of obviousness and double patenting.
- The broader patent landscape includes multiple patents covering different aspects of aripiprazole.
- Generic drug manufacturers face significant legal hurdles in attempting to market generic versions of aripiprazole.
Frequently Asked Questions (FAQs)
What is the main compound claimed in the '528 patent?
The main compound claimed in the '528 patent is aripiprazole, an atypical antipsychotic agent used to treat schizophrenia and other central nervous system disorders.
What are the key claims of the '528 patent?
The key claims include Claim 12 (aripiprazole by chemical name), Claim 16 (pharmaceutical composition for treating schizophrenia), Claim 17 (specifically identifying aripiprazole in the composition), and Claim 23 (method of treating schizophrenia using aripiprazole).
Why is the '528 patent significant in legal battles?
The '528 patent is significant because it has been at the center of numerous legal battles involving generic drug manufacturers who have submitted ANDA filings to the FDA, which Otsuka has challenged for patent infringement.
How does the '528 patent relate to other patents covering aripiprazole?
The '528 patent is part of a larger portfolio of patents covering aripiprazole, including patents such as U.S. Patent Nos. 7,053,092, 8,017,615, and others that cover various aspects of the drug.
What is the impact of the '528 patent on generic drug manufacturers?
The '528 patent significantly impacts generic drug manufacturers by preventing them from marketing generic versions of aripiprazole until the patent's exclusivity period expires, due to Otsuka's successful defense of the patent against infringement claims.
Cited Sources:
- Otsuka Pharm. Co. v. Sandoz, Inc., 678 F.3d 1280 - Casetext
- Otsuka Pharm. Co. v. Zydus Pharms. U.S. & Cadila Healthcare Ltd. - Casetext
- Patent Claims and Patent Scope - SSRN
- United States Patent (19) 5,006,528 - googleapis.com
- Case 1:15-cv-00161-JBS-KMW Document 130 Filed 11/16/15 - GovInfo
