May 2 (MSN Money) - A new study of Canadian health records found that first-time users of Merck's withdrawn painkiller Vioxx had the highest risk of heart attack after only two weeks, delivering a blow to the US drugmaker's litigation defences.
Merck faces a wave of litigation after it withdrew Vioxx from the market in September 2004, when a company study found increased heart risks after 18 months' usage.
A quarter of 239 Vioxx users who had a heart attack
experienced it between six and 13 days from their first
prescription, according to the study to be published in
the Canadian Medical Association Journal (CMAJ).
The study used records of about 114,000 elderly
Quebec patients. "We demonstrated that, among elderly
users of predominantly low doses of these agents,
short-term use of rofecoxib [Vioxx] is not without
risk," the study said.
This conclusion contradicts one of Merck's most
steadfast legal defences, and creates problems in its
efforts to fight at least 11,500 lawsuits potentially
worth billions of dollars in liability.
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inconvenience caused.Merck argues that Vioxx's heart
attack risk only begins after 18 months of continuous
use, and says its clinical trials have shown no
increased risks from short-term use.
Moreover, Merck plays down studies such as this one –
which analyse medical database records – as being less
scientific and less instructive than its own clinical
trials.
Merck responded to the study yesterday saying: "While
we have not seen the results of the specific study, it
is important to remember that this is an observational
study. Merck continues to believe that randomised
clinical trials provide stronger evidence than
observational studies."
The CMAJ study admitted that it had not taken into
account varying health factors in the patients, but also
said Merck's studies could have been too small to detect
such risk in short-term use.
The study was approved by the ethics boards of Quebec
province, Royal Victoria Hospital and McGill University.
Most of the lawsuits Merck is facing are likely to be
short-term use cases, and such a study is certainly to
be used by plaintiffs' attorneys fighting the drugmaker
in court.
Nevertheless, Merck has vowed not to settle any of
the cases, and to fight each one in a long litigation
war with the plaintiffs. It has reserved at least $1bn
for expected legal defence costs over several years.
More trials are expected to take place this year in
New Orleans federal court and New Jersey state court.
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