The Joseph Saveri Law Firm, LLP filed an antitrust class action lawsuit in December 2014 in Alameda County Superior Court (CA) on behalf of a proposed class of end payor plaintiffs who indirectly purchased, reimbursed, or otherwise paid for all dosage strengths of extended release oxymorphone hydrochloride tablets sold by defendents Endo Pharmaceuticals Inc. and Impax Laboratories. The suit seeks monetary damages for affected consumers. The case was sent to federal court and consolidated with similar cases in the U.S. District Court for the Northern District of Illinois - Eastern Division: In Re Opana ER Antitrust Litigation, MDL No. 2850.

Plaintiffs allege that Endo entered into an illegal reverse payment agreement with Impax, paying out more than $100 million in cash in exchange for Impax’s promise to keep generic versions of the painkiller Opana ER off the market for several years. Purchasers of Opana ER blame the companies for limiting generic competition and enabling Endo to hike prices for Opana ER.

On June 4, 2021, the Court granted class certification to direct purchaser plaintiffs and end payor plaintiffs.