December 13, 2010 – Based on emerging safety information, the pulmonary arterial hypertension (PAH) drug sitaxentan is being voluntarily withdrawn from the market. Pfizer is also discontinuing studies involving sitaxentan (Thelin) worldwide,
The company’s decision was based on a review of emerging safety information from clinical trials and post-marketing reports. While liver toxicity is a known complication of that class of drugs, a new potentially life-threatening idiosyncratic risk of liver injury has been observed. Given the availability of alternate treatments, Pfizer has concluded that the overall benefit no longer outweighs the risk in the general population of PAH patients. Health authorities have been notified about this finding and the decision to voluntarily withdraw sitaxentan and stop clinical studies.
The company recommends that no new patients be prescribed sitaxentan and that patients receiving it be transitioned to appropriate alternate therapies as soon as safely possible. Patients taking sitaxentan or participating in studies are advised to consult with their healthcare professional as soon as possible. Patients should not stop taking it until they speak to their healthcare professional.
Sitaxentan is approved in the European Union, Australia and Canada to treat patients with pulmonary arterial hypertension. Pulmonary arterial hypertension is a rare, progressive, life-threatening disease that may result in heart failure and premature death.
For more information: www.pfizer.com
November 19, 2025 
