Pfizer has voluntarily withdrawn Thelin (sitaxentan) for the treatment of pulmonary arterial hypertension (PAH) in regions where it is approved (the European Union, Canada and Australia), in the “interest of patient safety.” In addition, Pfizer is discontinuing clinical studies of Thelin globally.

The New York City-based company said its decision was based on a review of emerging safety information from clinical trials and post-marketing reports, which revealed a new potentially life-threatening idiosyncratic risk of liver injury with Thelin, in addition to the known complication of liver toxicity with its drug class.

Given the availability of alternate treatments, Pfizer concluded that the “overall benefit of Thelin no longer outweighs the risk in the general population of PAH patients.” The company has notified health authorities about this finding and its decision to voluntarily withdraw Thelin from the market and stop clinical studies.

Pfizer recommends that “no new patients be prescribed Thelin and that patients receiving Thelin be transitioned to appropriate alternate therapies as soon as safely possible. … Patients taking Thelin or participating in Thelin studies are advised to consult with their healthcare professional as soon as possible.”

Thelin is approved in the European Union, Australia and Canada to treat patients with pulmonary arterial hypertension—a rare, progressive, life-threatening disease that may result in heart failure and premature death.