Vioxx side effects reconfirmed

Another study published in the Annals of Medicine this month by Linda E. Lévesque, BScPhm, MSc; James M. Brophy, MD, PhD; and Bin Zhang, MSc will further add to the confusion whether Celebrex is indeed a safe drug. (Related article: Celebrex safety update from Pfizer)

In the study entitled "The Risk for Myocardial Infarction with Cyclooxygenase-2 Inhibitors: A Population Study of Elderly Adults", these scientists at the McGill University in Canada assessed the influence of various NSAIDs on the risk for a first myocardial infarction (MI). The study reconfirmed the serious adverse side effects of Vioxx, which was recalled by Merck in September of last year, but clearly leave open the question of safety of Celebrex. (Related article: History of Vioxx and its recall by Merck)

Their study provides evidence of an increased risk for myocardial infarction, nonfatal and fatal, with current use of rofecoxib (Vioxx), even in individuals with no history of myocardial infarction. The concomitant use of aspirin in persons using low-dose rofecoxib (Vioxx) appears to mitigate this risk. Although the observational nature of their study limits the ability to assign causality, the totality of the current evidence confirms the increased cardiovascular risk associated with rofecoxib (Vioxx) and the sagacity of its withdrawal. (Related article: FDA should have never approved Vioxx)

The scientists are, however, cautioning against drawing any conclusions about Cox-2 inhibitors drugs in general, and more specifically, Celebrex. They write, "Of equal importance, we provide evidence against a broad class effect for COX-2-mediated cardiotoxicity when used at usual doses." That does not mean that other Cox-2 drugs are safe and there is no reason to worry. They recommend more careful prescription of these drugs, "Nevertheless, given the widespread use of these agents and the increased risk seen in a recent cancer trial of high-dose celecoxib (Celebrex), further research should be undertaken. Until evidence to the contrary is available, new agents with COX-2 inhibitory potency similar to or greater than that of rofecoxib (Vioxx) should be used only with extreme caution, even in populations at relatively low risk for cardiovascular events." (Related article: Celebrex increases risks of heart attacks)

While the researchers admit that considerable uncertainty remains regarding the clinical profile of persons at risk for COX-2-mediated cardiovascular events and whether celecoxib (Celebrex), as well as other COX-2 selective agents, poses a similar risk. No increased risks were observed with celecoxib or the other NSAIDs, they find. This is exactly what Pfizer has been saying all along though there are other studies that prove otherwise. (Related articles: Pfizer stands by the safety of Celbrex and Consumer Group charges that Pfizer hid safety data on Celebrex)

So what does it mean? Simply that there is no definitive proof either way about Celebrex. The FDA experts will meet in less than two weeks to discuss what to do next with Cox-2 drugs like Celebrex and Bextra. The European Medicines Agency is already reviewing these drugs and will closely watch what the FDA decides in the United States.

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