Pfizer has announced the U.S. Food and Drug Administration (FDA) approval of their Janus kinase (JAK) inhibitor Xeljanz XR (tofacitinib citrate) for the treatment of rheumatoid arthritis (RA). Xeljanz XR is the first and only once-daily JAK inhibitor approved to treat RA.

The extended-release 11 mg tablets are indicated for the once-daily treatment of moderate to severe RA patients who have had an inadequate response or intolerance to methotrexate (MTX). Xeljanz XR is the only JAK inhibitor included in the 2015 American College of Rheumatology Guideline for the Treatment of Rheumatoid Arthritis

“The availability of Xeljanz XR provides physicians with a new treatment option for people with RA who may prefer an oral once-daily treatment,”  Roy Fleischmann, MD, clinical professor, Department of Internal Medicine, University of Texas Southwestern Medical Center and co-medical director, Metroplex Clinical Research Center, Dallas, said in the release.

Xeljanz XR, which is pharmacokinetically equivalent to Xeljanz 5 mg administered twice daily, works by interrupting signaling of several cytokines involved in immune response. The efficacy and safety profile of Xeljanz has been studied in roughly 6,200 patients with moderate to severe RA, amounting to more than 19,400 patient-years of drug exposure in the global clinical development program, Pfizer said.

The most common adverse reactions in clinical trials were upper respiratory tract infections, headache, diarrhea, and inflammation of the nasal passage and the upper part of the pharynx. The drug carries a boxed warning regarding an increased risk for serious infections, including opportunistic infections, tuberculosis, cancers, and lymphoma.

Xeljanz was approved by the FDA in 2012 for the treatment of moderate-to-severe active RA in adults, and was later approved as a second-line therapy after failure of one or more disease-modifying antirheumatic drugs (DMARDs) in more than 45 countries.