The settlement was disclosed in court papers filed in U.S. District Court in Newark, N.J., on Wednesday. Pfizer confirmed the accord Thursday, which resolves litigation with Impax but not another company over generic versions of the extended release capsule drug.

"The terms of this agreement are confidential," Christopher Loder, a spokesman for Pfizer, said in a statement.

Court papers state that Impax has agreed that except as allowed under a licensing agreement it will be barred from making or selling generic Detrol LA, or extended-release loiterodine tartraie, while two of Pfizer's patents remain valid.

Mark Donohue, a spokesman for Impax, declined comment.

Pfizer filed the lawsuit in March 2008 after Impax notified the New York company it had filed an application with the U.S. Food and Drug Administration seeking approval to market a generic version of Detrol LA.

Another generic manufacturer, Mylan Pharmaceuticals Inc., later similarly sought FDA approval to market a Detrol LA generic drug. It was subsequently also sued by Pfizer in 2010 and remains a party to the litigation.

Detrol and Detrol LA had revenues of $400 million in the first half of 2012, Pfizer said in its August 9 quarterly report. Revenues for the drug were down from $455 million during the same period a year earlier.

Pfizer in the report said the basic patent for the drug expires this September. Three other formulation patents expire in 2020, the company said.

The case is Pfizer Inc., et al v. Impax Laboratories, Inc., U.S. District Court for the District of New Jersey, 08-cv-02137

(Reporting By Nate Raymond in New York; Editing by M.D. Golan)

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