Vioxx, Bextra, and Celebrex are NAIDs (Non-steroidal anti-inflammatory
drugs). They are also called cox 2 inhibitors and were developed to treat
arthritis. The older NAISDs like aspirin, ibuprofen, and naproxin worked just
as well but they were cox 1 and cox 2 inhibitors and, over time, could cause
stomach irritation, bleeding, and ulcers. All these drugs block the cox 2
enzyme when there is inflammation. The cox 2 enzyme is also produced by pre-
cancerous tissues. But cox 2 also plays an important part in controlling the
cardiovascular system--stopping platelets from forming thrombi and preventing
damage to blood vessels. Vioxx was voluntarily withdrawn and in April 2005 the
FDA required Bextra to be taken off the market. It seems likely that Celebrex
will meet the same fate. There are lawsuits pending against the makers of all
three drugs.
The cox 2 inhibitors and cancer research
Ironically, the cox 2 inhibitors have shown great promise in preventing or
slowing the growth of cancer. Researchers at Jefferson
Medical College
have shown that elevated levels of cox 2 were found in breast cancers. The
Journal of the Canadian Opthalmology Society reported that researchers found
high levels of cox 2 in uveal melanoma and that cox 2 inhibitors could prevent
this. At the University of North
Carolina, research indicated that Celebrex slowed
the growth of prostate cancers. By 2004 the NCI (National Cancer Institute) had
40 clinical trials under way using cox 2 inhibitors.
The bad news
The NCI study on Celebrex and cancer was pulled because it showed that the
chance of heart attacks and strokes were increased by 2.5 at 400 mg. and 3.4
times at 800 mg a day. Some researchers say they have not had this result in
their own studies but many others say they have also. Some doctors argue that
with some cancer patients the benefits outweigh the risks and that patients
with a family history of cancer, early signs of cancer, or early biochemical
evidence of recurrence should take Celebrex.