On 25 April 2025, Impax Laboratories, LLC filed suit in the United States District Court for the District of New Jersey against Qilu Pharmaceutical (Hainan) Co., Ltd., asserting infringement of five U.S. patents — US8557283B2, US9463246B2, US9089608B2, US9533046B2, and US9901640B2 — all relating to RYTARY® carbidopa/levodopa extended-release capsules for oral use in four dosage strengths (23.75/95 mg, 36.25/145 mg, 48.75/195 mg, and 61.25/245 mg). The trigger was Qilu's ANDA No. 220177, which included a Paragraph IV certification challenging the patents-in-suit.

The recorded basis of termination is 'Case Settled.' The docket order, entered 10 April 2026, reflects a stipulated dismissal of all claims, counterclaims, and affirmative defenses without prejudice, referencing an underlying settlement agreement whose specific terms are not disclosed in the available public record. Notably, the dismissal order expressly preserves Qilu's right to maintain its Paragraph IV certification and does not prohibit the FDA from granting final approval to ANDA No. 220177 at any time. The court retained jurisdiction to enforce the settlement agreement.

The case resolved in approximately 350 days — well within the Hatch-Waxman 30-month stay period that would have automatically delayed FDA final approval had the suit been filed before ANDA approval. Each party bears its own fees and costs under the stipulation. What drove the settlement, any licensing or market-entry arrangements, and whether any exclusivity period was agreed upon are not disclosed in the available record. The preservation of Qilu's Paragraph IV certification and the court's explicit non-prohibition on FDA final approval are commercially significant terms visible in the public order.