By Michael Calia 

Actavis PLC and Pfizer Inc. said they settled all patent litigation over the generic version of painkiller Celebrex, which may allow Actavis to start marketing its version before the end of the year.

Actavis said Pfizer has granted it license to start marketing its generic version of Celebrex in December or perhaps earlier pending FDA approval.

The Actavis agreement comes a week after rival generic drug maker Teva Pharmaceutical Industries Ltd. said it had reached a similar deal with Pfizer.

Pfizer confirmed it had reached a settlement with Actavis subsidiary Watson Laboratories Inc., saying that the license will bear royalties through the remaining term of the patent, which ends on Dec. 2, 2015.

The remaining terms of the pact are confidential. Pfizer said it would continue defense of the patent, however.

Pfizer in March said a federal court invalidated a patent that would have given it another 18 months of exclusivity in the U.S. for Celebrex. The company previously had brought a patent-infringement cast against six generic drug producers, including Teva, Actavis and Mylan Inc.

Mylan said last month that it, too, plans to start selling its generic version of Celebrex following the March court decision.

Actavis said Thursday that it believes it might be a so-called first applicant to file an abbreviated new drug application for generic Celebrex. If so, the company could be entitled to 180 days of exclusivity or shared exclusivity on the generic market.

Write to Michael Calia at michael.calia@wsj.com

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