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Back to Rheumatology Articles
Monday 21st February, 2005
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Vioxx found to double the risk of
developing a cardiovascular "event" when compared to placebo.
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HOUSTON - The largest prospective trial ever examining
the anti-inflammatory drug Vioxx as a chemoprevention agent
found that the risk of developing a cardiovascular "event" -
heart attacks and/or strokes - was almost double in patients
who received the drug, compared to patients who took the
placebo, according to a study out Feb. 15 on-line in The New
England Journal of Medicine.
The risk was first discovered and reported last September by the
study's safety monitoring board and led to the shutdown of the colon
cancer chemoprevention trial and subsequent withdrawal of the drug
from the U.S. market.
The trial, known as APPROVe (Adenomatous Polyp Prevention on
Vioxx), was the longest test yet of Vioxx as a chemoprevention
agent, and was designed to determine whether the drug could prevent
the re-growth of precancerous colon polyps in people who had already
had polyps removed. The prospective chemoprevention study randomized
2,586 participants from 108 centers in 29 countries to receive
either 25 mgs. of Vioxx daily or a placebo drug for three years,
2001-2004. The trial was stopped September 30, 2004 - approximately
two months before its planned completion.
According to Robert S. Bresalier, M.D., of The University of
Texas M. D. Anderson Cancer Center and lead author of The New
England Journal of Medicine study, 46 of the 1287 patients
randomized to take Vioxx daily had confirmed cardiovascular events
over a three year period - mostly heart attacks or strokes. In the
1,299 patients given a placebo drug, there were 26 events. Each
group, however, had the same number of deaths and not all were
related to heart attacks or strokes.
"The overall number of cardiovascular events is small, but,
nevertheless, the difference between the groups is significant,"
says Bresalier, who is professor and chair of the Department of
Gastrointestinal Medicine and Nutrition at M. D. Anderson and a
member of the study's steering committee.
This study examined data on the 2,586 patients enrolled in the
trial, all of whom had a history of adenomatous colon polyps. The
most notable trend, according to Bresalier, was that patients did
not begin to experience cardiovascular problems such as heart
attacks or strokes until after 18 months of treatment. "In the first
18 months, the risks for the two treatments were similar," Bresalier
says.
Other cardiac problems, such as hypertension-related events,
pulmonary edema and congestive heart failure-related events were
much more prevalent in the Vioxx-treated group compared to the
placebo group and presented earlier. The data on these cases,
however, is less firm, Bresalier notes, because, unlike heart
attacks or strokes, these problems were not "adjudicated," or
validated by a separate committee. This was not a cardiovascular
trial, reminds Bresalier, so while investigators reported all
events, only the most serious were fully examined.
"Because patient benefit is the most important criteria for any
study, it was appropriate to stop the trial," Bresalier says. "We
don't know why Vioxx increased this risk, but we now have an
opportunity to study whether subpopulations of patients are more
susceptible than others."
"I think it's unfortunate that we've perhaps lost a class of
drugs which potentially has very important roles in a variety of
diseases - arthritis, cancer prevention, cancer treatment, treatment
of Alzheimer's disease, treatment of precancerous lesions, not only
in the colon but in the esophagus and many other organs," says
Bresalier. "What we don't know is, if the cardiovascular results
seen in Vioxx represents a class effect of COX-2 inhibitors or if
this is an individual effect to this drug. I don't think we can tell
this from this one trial or from the trials that are out there at
the moment. That's going to be the real question."
The investigators examined the use of cardio-protective aspirin
among patients and found that it did not skew findings on the
overall risk of Vioxx treatment.
Sources:
University of Texas M. D. Anderson Cancer Center
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