Pfizer Sues MSN Labs to Block Copies of Xeljanz Arthritis Drug

Pfizer Inc. alleges that MSN Laboratories Private Ltd.’s proposed generic versions of Xeljanz tablets and oral solution infringe a patent for the blockbuster arthritis drug, according to a federal lawsuit in Delaware.

MSN Labs wants to sell copies of Xeljanz’s twice-daily 5- and 10-milligram tablets and of its twice-daily oral solution, according to a complaint filed Monday in the US District Court for the District of Delaware. Pfizer seeks court orders blocking the copies until the patent has expired.

Xeljanz, whose active ingredient is tofacitinib citrate, also comes in 11- and 22-mg extended-release tablets, but those formulations aren’t subjects ...