Pfizer reaffirms Celebrex safety

Pfizer on Monday disputed an allegation by Public Citizen that the company hid and downplayed the results of a test of the arthritis drug Celebrex that clearly showed a higher risk of heart attacks. (Related article: Consumer group asks FDA to ban Celebrex) Pfizer said that "definitive conclusions about cardiovascular risk cannot be drawn from this study." Like arguments presented by Merck in the past that Vioxx did not injure arthritis patients (on the other hand, they already had a medical condition that made them sick), Pfizer is saying something similar that participants in the study who took Celebrex were already quite sick and that is why the higher heart attack risks seen in those patients who took Celebrex. (Related article: Pfizer's position on safety of Celebrex)

In this study, Pfizer admitted that Celebrex patients experienced "more cardiovascular events than patients taking a placebo. However, Celebrex patients "were up to four times more likely to have key cardiovascular risk factors" vs. the placebo patients, thus impairing the findings.
However, disclosure of this study contradicts a series of statements by Pfizer in form of press releases and interviews by its CEO Hank McKinnell. (Related article: FDA warns Pfizer about misleading Celebrex ads)

Dr. Gail Cawkwell, Pfizer's medical team leader for Celebrex was essentially evasive and pleaded ignorance on many disturbing questions about the study. For instance, she said she did not know whether the study's safety data had been presented at a conference in Sweden in 2000 and that she also did not know why Pharmacia (the company that discovered Celebrex and Bextra and was acquired by Pfizer in 2002) did not send the results to the F.D.A. in time for the broader review. (Related article: Pfizer refuses to recall Celebrex)

There is no consensus yet among scientists that the study cited by Public Citizen conclusively shows that Celebrex should be immediately banned. Linda E. Lévesque; James M. Brophy; and Bin Zhang (of McGill University) writing in the Annals of Medicine find that risks for heart attacks were very high with Vioxx but did not find the same level of risks with Celebrex. But they are aware of other studies that do show risks with Celebrex. "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," the scientists recommend. (Related article: FDA limits Celebrex and Bextra use after Vioxx recall)

The New York Times quotes Dr. Kenneth Brandt, a professor of medicine at Indiana University School of Medicine, and one of the members of the panel that reviewed Celebrex in 2001, as saying that if the safety panel had known about the study, it might have recommended that both Vioxx and Celebrex be taken with greater caution.

Dr Eric Topol, world-famous cardiologist and considered to be an authority on the side effects of Cox-2 inhibitor drugs, is not convinced that Celebrex is as dangerous as Vioxx based on the study disclosed by Public Citizen, though he has always advised caution in prescribing it till more information is available. He is quoted in Forbes as saying, "I'm not trying to discount the importance of the study. It should have been published." Garret FitzGerald, a pharmacologist at the University of Pennsylvania, however, says in the same Forbes article that although the results are "far from conclusive," they do point toward increased risk for Celebrex.

Apart from personal injury attorneys who have been filing lawsuits against Pfizer citing problems with Celebrex and Bextra, the investors are equally concerned. "That we now have two different data sets showing a CV [cardiovascular] signal is increasingly worrisome, yet we don't think withdrawal of the product is in the offing -- a more realistic outcome, in our opinion, would be revisions made to product labeling that could then impact future commercial performance," the Prudential analysts wrote in a report analyzing the impact of Celebrex recall on Pfizer.

Celebrex and Bextra were not the only Pfizer drugs in news yesterday. The trial of Christopher Pittman began with claims from the defense that he was led to kill his grandparents by the antidepressant drug Zoloft. Pittman, who had threatened suicide, was put on Zoloft three weeks before the slayings, and his dose was doubled just two days earlier. In October of 2004, the Food and Drug Administration ordered Zoloft and other antidepressants to carry "black box" warnings - the government's strongest warning short of a ban - about increasing the risk of suicidal behavior in children. Pfizer has vigorously fought cases claiming antidepressants cause violent or suicidal behavior. Eli Lilly, the maker of Prozac, has also vigorously argued that the drug leads to suicidal behavior.

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