Invalidity dossier
US 6576259
Sustained release formulations containing tacrolimus
Current assignee: Astellas Pharma Inc
Added 9/23/2026, 8:46:49 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US 6,576,259 B2
Title: Sustained release formulations containing tacrolimus
Patent number: US6576259B2
Application number: US09/978,025 (filed 2001-10-17)
Publication date: 2003-06-10
Priority date: 1998-03-26 (stated as an assumption, not a legal conclusion)
Original assignee: Fujisawa Pharmaceutical Co Ltd
Current assignee (as listed): Astellas Pharma Inc
Status (as listed): Expired – Lifetime; anticipated expiration 2019-03-25
Inventors: Kazunari Yamashita, Eiji Hashimoto, Yukihiro Nomura, Fumio Shimojo, Shigeki Tamura, Takeo Hirose, Satoshi Ueda, Takashi Saitoh, Rinta Ibuki, Toshio Ideno
Purpose and plain-language scope (from the supplied text):
The patent concerns sustained release formulations containing tacrolimus, a macrolide antibiotic also described as an immunosuppressant used in transplantation and autoimmune disease. The indexed subject matter indicates the formulations are solid (powder, granule, capsule, tablet forms are referenced), employ a water-soluble polymer such as hydroxypropyl cellulose, and may involve a solid dispersion. Testing methods referenced include dissolution and dissolution tests. Other indexed excipients include lactose, hydroxypropyl methyl cellulose, sucrose, dicalcium phosphate, and magnesium stearate, with fatty acid esters/fatty acids also noted. Tacrolimus and sirolimus (rapamycin) appear among the disclosed compounds. The listed family includes related filings (US6884433B2, US8551522B2) and a Delaware District Court litigation entry.
Source: https://patents.google.com/patent/US6576259/en
What the excerpt does not establish:
This is only a partial excerpt. It does not supply the full claims, written description, examples, or figures, so the precise claimed scope (e.g., specific components, ratios, or dissolution profiles) cannot be stated. It does not establish the actual legal status, the enforceability or validity of any claim, the outcome of any litigation, or the accuracy of the listed assignees or dates—the source itself labels these as assumptions or non-legal conclusions. No independent prior-art analysis is presented here (and none was researched, per instruction). The excerpt contains no verified dosing, clinical, or safety data.
Generated 10/1/2026, 9:41:10 PM
Cases on file (0)
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Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
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No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.