New painkiller increases cardiac risk, study shows
Tuesday, January 19, 1999
CAROLYN ABRAHAM
Medical Reporter
Just weeks after an eagerly awaited new
painkiller received rushed approval in the United
States, a new study suggests the so-called
SuperAspirin may have some weaknesses.
The COX-2 inhibitor, touted as a new class of
anti-inflammatory drug, was specifically crafted
to shut off a tiny enzyme in the body that
produces pain. Doctors and patients have
clamored for it because, unlike existing
painkillers, the SuperAspirin promised no serious
side effects.
But a paper published this month in the
Proceedings of the National Academy of Science
journal finds the COX-2 inhibitor also blocks a
hormone-like substance that dilates blood vessels
and inhibits blood clotting. This raises questions
about whether the SuperAspirin might increase
the risk of heart attacks, strokes and blood
clotting.
The truth is, no one knows.
No research has ever studied what happens to
people when the hormone-like prostacyclin is
blocked. In mice, the result was increased blood
clotting.
"We have biochemical evidence that it disrupts a
delicate balance . . . but whether this translates
into real events in people, like heart attacks, we
don't know," says Brendan McAdam, a
cardiologist who led the research at the
University of Pennsylvania's Centre for
Experimental Therapeutics. "It remains, in
theory, a cause for concern."
Dr. McAdam, who now works at Vanderbilt
University in Nashville, says further studies are
needed to determine how people fare when their
prostacyclin is blocked.
It is unclear what impact the study will have on
Health Canada officials who are considering
whether to approve the first Cox-2 inhibitor,
brand named Celebrex.
Any suggestion that the drug could increase
cardiac problems is bound to be a significant
concern, however. The drug's primary users are
expected to be arthritis sufferers, largely elderly
people who, because of their age, already have a
higher risk of heart disease.
But the drug's manufacturer, G. D. Searle, which
sponsored the Pennsylvania study, presented the
findings to the U.S. Food and Drug
Administration. And despite the presentation, the
FDA fast-tracked approval of Celebrex on Dec.
31.
Searle spokesperson Scarlett Foster, says the
concerns should not be overblown.
"This is only a hypothesis based on tests that
were only done invitro, done only in the lab, but
we've done clinical trials with more than 13,000
people [including many in Canada]," Ms. Foster
said in an interview yesterday. "The trials showed
no elevated heart problems."
In fact, last fall a Canadian rheumatologist
involved in clinical trials called the lack of
apparent side effects remarkable.
Francesca Catella-Lawson, a clinical
pharmacologist who is continuing a review of
Celebrex at the University of Pennsylvania, says
another soon-to-be-published study examines the
drug's effects on kidney function.
While Dr. Catella-Lawson would not disclose
those findings, she did say mice who had had
COX-2 inhibitors also had kidney problems.
Attention on the SuperAspirin and its potential
cryptonites will likely increase this year as other
major drug firms, namely Merck & Co., come to
market with their brands of COX-2 inhibitors.
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