Pfizer withdraws hypertension drug Thelin
pharmafile | December 14, 2010 | News story | Sales and Marketing | PAH, Pfizer, Thelin, liver damage, liver toxicity, patient safety, pulmonary arterial hypertension, sitaxentan
Pfizer has suffered a blow to its drug development programme with the withdrawal of pulmonary arterial hypertension (PAH) brand Thelin due to the threat of life-threatening liver damage.
Pfizer is voluntarily removing the drug, which is approved in the European Union, Canada and Australia, from the $2.5 billion global PAH market.
The manufacturer is also halting all trials worldwide of Thelin (sitaxentan) “in the interest of patient safety”.
“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,” the company said in a statement.
Sales of the orally-active once-daily endothelin A receptor antagonist are thought to be around $50 million per year.
The decision to pull it came after a review of safety information from clinical trials and post-marketing reports.
“Pfizer’s priority is to ensure the safety and well-being of patients,” said Cara Cassino, vice president, clinical development and medical affairs for Pfizer’s Pulmonary Vascular Disease unit.
“We are in the process of communicating all of this information to the appropriate medical professionals and regulatory authorities in all regions as quickly as possible,” Cassino added.
Given the availability of alternative PAH treatments – such as its own Revatio (sildenafil citrate) – Pfizer says Thelin’s benefit does not outweigh its risk.
In May, the company signed an agreement to acquire terguride, a PAH drug currently in phase II testing, from Swiss company Ergonex GmbH.
The orally-active antagonist of serotonin 5-HT2B and 5-HT2A receptors has a different mechanism of action to Thelin and Revatio.
The current market leader, Actelion’s endothelin antagonist Tracleer (bosentan), is to lose patent protection after 2015.
Pfizer recommends that no new patients are prescribed Thelin and that those receiving it should be moved to other therapies as soon as possible.
But it warns that those taking the drug should not stop doing so until they have spoken to their doctor.
The Thelin move comes hard on the heels of suggestions Pfizer hired investigators to uncover evidence of corruption by a top government official in Nigeria in order to have a clinical trial lawsuit dropped.
The company was sued after a 1996 meningitis trial in which 11 children died during the testing of its antibiotic Trovan.
In a busy media week for the company, which also saw a number of senior executives leave the company, Pfizer dismissed the claims published by whistleblowing website WikiLeaks as “preposterous”.
Adam Hill
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