Pfizer, the world’s largest pharmaceutical company, has agreed not to launch its COX-2 inhibitor, Onsenal (celecoxib), in the European Union for treating a condition known as familial adenomatous polyposis — a rare genetic disease that can result in colorectal cancer – until further safety checks have been carried out on the class of drugs, the agency has revealed.

Onsenal, which contains the same active ingredient as Pfizer’s top-selling pain-killer, Celebrex, won the green light from Europe’s scientific advisory body, the CHMP, to treat this rare condition in the summer of 2003 [[08/07/03d]]. However, the firm has agreed to delay its launch after the European regulators asked for “further clarifications and analyses” of data from the company, with particular regard to the Adenoma Prevention with Celecoxib and Prevention of Spontaneous Adenoma Polyps studies.

The news came after the European regulators' meeting to discuss the safety of the COX-2 inhibitor class of drugs, which was triggered by Merck & Co’s withdrawal of its offering, Vioxx (rofecoxib), after it was linked to a doubling in the risk of heart attack and stroke [[01/10/04a]]. Celebrex has also been linked to a heightened risk of heart attack [[20/12/04a]].

Data on other COX-2 inhibitors – Pfizer’s Dynastat (parecoxib) and Bextra (valdecoxib), Merck & Co’s Arcoxia (etoricoxib), and Novartis’ Prexige (lumiracoxib) – are currently being assessed, and the CHMP will continue its discussions on the review at its next meeting, set to be held on February, 14-17.