(Adds further background on litigation, quotes from judge)
By Nate Raymond
BOSTON, March 29 (Reuters) - Impax Laboratories Inc has agreed to pay $20 million to consumers and insurers to resolve claims that the drugmaker entered an anticompetitive deal to delay launching a generic, cheaper version of acne medication Solodyn.
The accord, disclosed in papers filed in federal court in Boston, brought to an end a rare trial in a class action lawsuit involving an alleged "pay-for-delay" patent litigation settlement between a brand-name drugmaker and a generic company.
Such settlements occur when a brand-name drugmaker pays a generic rival to delay releasing a cheaper version of its product in exchange for resolving court challenges to patents covering the treatment.
According to the plaintiffs, Impax in 2008 settled a lawsuit it filed challenging a weak patent Medicis Pharmaceutical Corp held for Solodyn by agreeing to delay releasing its generic version until 2011.
In exchange, Impax received $40 million, allowing Medicis to maintain its Solodyn monopoly longer, the plaintiffs allege. But for that settlement, Impax would have launched its generic version "at-risk" while the litigation continued, they say.
Hayward, California-based Impax denied that there was any such arrangement to delay competition.
Thursday's settlement came in the third week of the trial and after the plaintiffs finished presenting their evidence against Impax, which in October agreed to combine with Amneal Pharmaceuticals LLC.
"It's a fair result," Douglas Baldridge, a lawyer for Impax, said outside of court.
The deal marked the final settlement in the litigation. Impax previously agreed to pay $35 million to resolve class action claims brought on behalf of direct purchasers of Solodyn such as retailers.
Mid-trial, Impax on Sunday settled lawsuits by retail pharmacy operators including CVS Health Corp, Rite Aid Corp, Walgreens Boots Alliance Inc, Kroger Co, Albertsons Companies Inc and HEB Grocery Company LP. Terms were not disclosed.
Valeant Pharmaceuticals International Inc, which acquired Medicis in 2012, said in February it would pay $58 million to resolve related claims.
Jurors had been asked only to determine liability because damages would have been determined at a later trial.
Lawyers for the consumers and insurers had alleged that because of the "pay-for-delay" settlement, they were overcharged by up to $790.3 million, according to an October court ruling.
"The fact that the case was presented to you had a lot to do with this case settling," U.S. District Judge Denise Casper told jurors before excusing them on Thursday morning.
The case is In re Solodyn (Minocycline Hydrochloride) Antitrust Litigation, U.S. District Court, District of Massachusetts, No. 14-md-02503. (Reporting by Nate Raymond in Boston; Editing by David Gregorio Editing by Chizu Nomiyama, David Gregorio and Susan Thomas)