Acadia Pharmaceuticals’ lawsuit against Aurobindo Pharma over generic pimavanserin has, so far, gone entirely Acadia’s way: the courts have upheld every challenged patent covering Nuplazid, and Aurobindo is blocked from launching a generic version of the 34 mg capsule potentially through August 2038.
How the Case Started
Acadia filed suit against Aurobindo on July 24, 2020, in the U.S. District Court for the District of Delaware (Case No. 1:20-cv-00985).1CourtListener. Acadia Pharmaceuticals Inc. v. Aurobindo Pharma Limited The trigger was the Hatch-Waxman framework: Aurobindo had filed an Abbreviated New Drug Application with a Paragraph IV certification, telling the FDA it intended to market a generic pimavanserin and asserting that Acadia’s patents were invalid or not infringed. That filing gave Acadia the right to sue.2PatSnap. Acadia Pharmaceuticals v. Aurobindo, MSN, Generic Filers – Pimavanserin
A companion case against MSN Laboratories (1:20-cv-01029) was filed the same year, along with related actions against Zydus, Hetero, and Teva. The court consolidated the actions for scheduling and assigned them to Judge Gregory B. Williams.1CourtListener. Acadia Pharmaceuticals Inc. v. Aurobindo Pharma Limited Nuplazid, approved by the FDA on April 29, 2016, is the first and only medication specifically indicated for hallucinations and delusions associated with Parkinson’s disease psychosis, which is why generic entry carries stakes on both sides.3Acadia Pharmaceuticals. FDA Approves Acadia Pharmaceuticals Nuplazid (Pimavanserin)
The Patents Aurobindo Had to Beat
Acadia’s protection for Nuplazid is layered. The composition-of-matter patent, U.S. Patent No. 7,601,740, covers pimavanserin itself and its tartrate salt; after patent term adjustment and regulatory extension, it expires April 29, 2030.4U.S. Court of Appeals for the Federal Circuit. Acadia Pharmaceuticals Inc. v. Aurobindo Pharma Ltd., No. 2024-14015Acadia Pharmaceuticals. Delaware District Court Rules in Favor of Acadia on Formulation Patent6U.S. Food and Drug Administration. ANDA Approval Letter for Pimavanserin A separate method-of-use patent protects the 10 mg tablet through 2037.7Acadia Pharmaceuticals. Delaware Federal District Court Rules in Favor of Acadia To reach the market, Aurobindo needed to break through more than one of these.
The ‘740 Composition Patent: Upheld and Affirmed
The first major battle turned on claim 26 of the ‘740 patent, which covers pimavanserin tartrate. MSN Laboratories, litigating in parallel with Aurobindo, argued the claim was invalid for obviousness-type double patenting, saying it was an obvious variation of a claim in Acadia’s later-expiring ‘271 method-of-use patent.
On December 13, 2023, Judge Williams granted summary judgment for Acadia, holding the ‘740 patent was not invalid. Final judgment followed on January 11, 2024, finding that MSN’s ANDA submission infringed and rejecting all of MSN’s invalidity counterclaims.8PatSnap. Acadia Pharmaceuticals v. MSN Laboratories – Pimavanserin Patent Infringement
MSN appealed. On June 9, 2025, the U.S. Court of Appeals for the Federal Circuit affirmed, applying the rule from Allergan USA, Inc. v. MSN Laboratories that “a first-filed, first-issued, later-expiring claim cannot be invalidated by a later-filed, later-issued, earlier-expiring reference claim having a common priority date.” Aurobindo itself did not appeal the ‘740 ruling; only MSN did.4U.S. Court of Appeals for the Federal Circuit. Acadia Pharmaceuticals Inc. v. Aurobindo Pharma Ltd., No. 2024-1401
The Pending En Banc Petition
On August 8, 2025, MSN petitioned for rehearing en banc, arguing the Allergan rule “violates the bedrock principle” of obviousness-type double patenting.9PatentlyO. Acadia Pharmaceuticals Inc. v. Aurobindo Pharma Ltd. – Petition for Rehearing En Banc Inari Agriculture filed an amicus brief in support.10Federal Circuit Blog. Recent En Banc Activity As of the most recent available information, the Federal Circuit had not ruled on the petition. If the full court took the case and reversed, the ‘740 patent’s status could be back in play.
The ‘721 Formulation Patent: Aurobindo Loses at Trial
The formulation patent covering the 34 mg capsule went to a bench trial in December 2024 against Aurobindo. On May 16, 2025, Judge Williams ruled that Aurobindo’s proposed generic capsules infringe the ‘721 patent and that Aurobindo failed to prove the claims invalid. The detailed opinion was filed under seal.11Bloomberg Law. Acadia Wins Patent Ruling Over Aurobindo’s Nuplazid Drug Copies
The court had already handed Acadia an earlier win on the same patent. On December 13, 2023, Judge Williams issued a claim construction order adopting Acadia’s interpretation of every disputed term, and the previously scheduled Markman hearing was cancelled.5Acadia Pharmaceuticals. Delaware District Court Rules in Favor of Acadia on Formulation Patent
What the Rulings Mean for a Generic Launch
The trial ruling bars Aurobindo from launching a generic 34 mg pimavanserin capsule until the ‘721 patent expires in 2038, absent a successful appeal.12Medpath. Acadia Pharmaceuticals Secures Patent Victory for Parkinson’s Drug Nuplazid Until 2038 The ‘740 affirmance separately blocks generic pimavanserin as a compound through April 2030. One industry analysis concluded that Nuplazid appears “safe from generic competition until well into the next decade.”13Pink Sheet (Citeline). Aurobindo, MSN Fail to Beat US Nuplazid Patent Expiring in August 2038
The Other ANDA Filers
Aurobindo and MSN are not the only generics that tried. Teva’s case (1:20-cv-00986) was stayed by a consent order on May 7, 2024. Teva agreed to be bound by the contested merits judgment against another defendant, cannot launch until the patents expire or a court rules in its favor, and cannot pursue inter partes review or other validity challenges during the stay. The agreement includes a most-favored-nation clause letting Teva match terms if Acadia settles with other defendants.14PatSnap. Acadia Pharmaceuticals v. Teva – Pimavanserin Patent Litigation
Zydus is the outlier. Its lawsuit was dismissed, and the FDA approved Zydus’s ANDA for pimavanserin 34 mg capsules, making Zydus eligible for 180 days of shared generic drug exclusivity.15U.S. Food and Drug Administration. ANDA Approval Letter – Pimavanserin Capsules, 34 mg (Zydus) The terms of that resolution are not detailed in public records, so whether and when Zydus can actually launch is not fully clear from what has been made available.