On Thursday, April 12 an FDA advisory panel will discuss
whether or not to recommend that the FDA approve Merck & Co’s COX-2
inhibitor, Arcoxia (etoricoxib). The drug is manufactured by Merck, the
same company that made Vioxx, which was pulled from the market in the fall of
2004. Merck applied for approval to sell Arcoxia as a treatment for the
signs and symptoms of osteoarthritis.
Currently, the only COX-2 inhibitor remaining on the market
is Celebrex, made by Pfizer, Inc. These COX-2 inhibitors are all types of
NSAIDs. Over the counter types of NSAIDs include naproxen (sold as Aleve)
and ibuprofen. The difference between the prescription COX-2s and the OTC
NSAIDS (and the big selling point) is that the COX-2s have a lower risk of
bleeding ulcers and other GI complications than other NSAIDs. However,
studies have shown that the COX-2s have a higher risk of heart attack and
strokes. Vioxx and Bextra were both subsequently pulled from the
market. Pfizer kept selling Celebrex, but stopped all direct to consumer
advertising in late 2004, early 2005. Pfizer has only begun advertising
Celebrex again this month.
According to documents released this week by the FDA, the
advisory panel will be focusing specifically on the cardiovascular risks of
this drug (and all other drugs from this class) when it evaluates Merck’s
application. Any NSAID will merit approval only if it fills an unmet need
for a particular group of patients and no other relatively safer alternatives
are available to them.
Although Arcoxia is currently sold in 63 other countries,
there has been a lot of criticism over the last year of the drug and of the way
that Merck designed the drug trials that it uses as evidence in its FDA
application. Merck compared Arcoxia to an older NSAID called diclofenac,
finding that the two drugs had similar rates of cardiovascular events.
Diclofenac is not commonly used in the
Critics of Arcoxia say that the Arcoxia/ diclofenac comparison
is flawed because the latter is a weaker drug. They say a better
comparison would have been to other NSAIDs like naproxen. Studies of
naproxen have not shown an increased cardiovascular risk. Merck did
compare Vioxx to naproxen and found that people taking Vioxx were 5 times as
likely to have heart attacks as those taking naproxen. Several smaller
studies, not performed by Merck, have compared Arcoxia to naproxen and found a
greater risk of heart attack and strokes in people taking Arcoxia than naproxen,
but less than other NSAIDs. Critics contend that not only should the FDA
not approve Arcoxia in the
