Pfizer Sues Alkem to Block Copies of Xeljanz XR Arthritis Drug

Alkem Laboratories Ltd.'s proposed copies of two extended-release Xeljanz dosages infringe a patent for Pfizer Inc.'s once-blockbuster arthritis drug, a federal lawsuit said.

Pfizer alleged Alkem’s generic versions of Xeljanz XR’s 11- and 22-milligram tablets infringe US Patent No. RE41,783, in a complaint filed Wednesday in the US District Court for the District of Delaware. The drug had US sales of $680 million in 2024, 41% less than in 2023, when its domestic revenue was $1.15 billion, Pfizer said in its annual earnings report.

• Xeljanz XR, whose active ingredient is tofacitinib citrate, is sold in those dosages as ...