Updated from 11:54 a.m. EST
dropped Thursday after a Canadian newspaper reported that the arthritis drug Celebrex is "suspected of contributing to at least 14 deaths."
A spokeswoman for Canada's health department, however, said there is no proof that the drug was linked to the deaths. "There hasn't been a causal link established," the spokeswoman told
"It may be connected to the 14 deaths or it may not have been connected to the 14 deaths. ... They could have been dying just because they were dying anyway."
Pfizer called the article "misleading," asserting that the story "is not supported by any clinical or epidemiological studies and has the potential to cause undue confusion among patients and physicians."
Referring to the Canadian government's criticism of the article, Pfizer added that "the safety profile for Celebrex is well-established and is supported by extensive clinical studies in Canada and around the world."
The National Post
, said its review of documents on file with the health department showed more than 100 adverse reaction reports on the drug over the past five years, including 19 cardiovascular events such as heart attack and stroke.
Pfizer said these adverse reaction reports must be checked carefully. "Voluntary, spontaneous event reporting to health authorities is not designed and cannot be used to determine cause and effect," the company said. "It is essential to remember that the information provided is uncontrolled and may be second-hand or incomplete."
Pfizer's shares dropped 58 cents, or 2%, to $28.87. The stock fell as low as $27.20 early in the day, before the Canadian government and Pfizer responded.
Pfizer has been promoting Celebrex as a safe alternative to Vioxx, the arthritis drug pulled from the market by
Sept. 30. Merck said it acted because a company-sponsored study showed long-term use of Vioxx -- more than 18 months -- produced a higher risk of cardiovascular problems in people who took the arthritis drug vs. those who took a placebo.
Since Merck pulled Vioxx, Pfizer has issued results of several studies to show that Celebrex doesn't cause the same problems. Pfizer announced recently that it is sponsoring long-term tests to assess the cardiovascular safety of Celebrex and a similar drug, Bextra. Both are COX-2 inhibitor drugs, just like Vioxx.