Pfizer is voluntarily withdrawing Thelin® (sitaxentan) for the treatment of pulmonary arterial hypertension (PAH) from Australia, Canada, and the EU, where they are approved. In addition, the firm is discontinuing worldwide clinical studies of this endothelin A receptor antagonist.
The 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 the class of drugs to which Thelin belongs, a new potentially life-threatening idiosyncratic risk of liver injury with Thelin has been observed.
Given the availability of alternate treatments, Pfizer noted that the overall benefit of Thelin no longer outweighs the risk in the general PAH patient population. Pfizer recommends that no new patients be prescribed Thelin and that patients receiving the drug be transitioned to appropriate alternate therapies as soon as safely possible.