The idea behind COX-2 inhibitors, such as Celebrex and Vioxx, was to spare the stomach lining by targeting only COX-2.
Nonetheless, the heart controversy has drastically slowed the growth of the whole cox-2 class and delayed the approval of additional cox-2 drugs.
But when the protein was attached to the mRNA for the Cox-2 enzyme, cancer cells could no longer make Cox-2, and they died, suggesting it plays a key role in tumour cell survival or death.
The new class of drugs, called Cyclooxygenase-2 or Cox-2 inhibitors, are no better at easing swelling or numbing hurt.
Vioxx is more selective, and Arcoxia is the most selective of all, blocking out Cox-2 while not affecting Cox-1.
They stop inflammation by blocking an enzyme called Cox-2 without also hitting a related enzyme called Cox-1.
Like Vioxx, it is an arthritis drug that works by inhibiting the enzyme known as COX-2, without knocking out another enzyme called COX-1.
Novartis (nyse: NVS - news - people ) is conducting similar trials for its experimental Cox-2 drug, still known by the codename Cox-189.
Needleman's theory was that one could spare the stomach by selectively blocking the enzyme responsible for inflammation, COX-2 (cyclooxygenase-2), while avoiding the one involved in maintaining the stomach lining, COX-1.
And Pharmacia's new injectable COX-2 inhibitor, called Dynastat, could supplement or even supersede morphine.
Colorectal polyps, which are precursors to colon cancer, were known to over produce COX-2.
FORBES: Vioxx and Diclofenac: Why Are Two Heart Risky Pain Drugs Viewed Differently?
In the meantime, analysts are somewhat sanguine about the prospects for the Cox-2 drugs.
Talley's second COX-2 entry, Bextra, was approved last year, beating out Merck's second version.
AstraZeneca has doped its version of a COX-2 inhibitor with nitrous oxide--laughing gas--to soften the gastrointestinal blow.
Left out in this research was acetaminophen, a brain drug that works on neither COX-1 nor COX-2.
Celebrex is the first of a new kind of painkiller called COX-2 inhibitors to get FDA approval.
"We really need to know whether cox-2 inhibitors are safe for patients with heart disease, " Nissen says.
Pfizer argues in a briefing document filed with the FDA that all Cox-2 drugs are not alike.
Novartis and GlaxoSmithKline (GSK) will have to decide the future of the COX-2 drugs in their pipelines.
So far, they are critical, seeing potential for heart risk in unapproved Cox-2 drugs developed by Novartis and Merck .
The Cox-2 inhibitors were only cost-effective, the authors concluded, in patients who already had a history of ulcers.
Due out in 2004, it may work faster and longer and cause fewer ulcers than other COX-2 inhibitors.
Hassan has high hopes for two second-generation COX-2 inhibitors, valdecoxib and parecoxib, which are finishing up testing now.
Beyond treating arthritis, it was believed that the COX-2 inhibitors might have other medical benefits as well.
FORBES: Vioxx and Diclofenac: Why Are Two Heart Risky Pain Drugs Viewed Differently?
Cox-2 inhibitors were prescribed broadly before benefits and risks had been fully determined.
Clinical use of Cox-2 drugs in association with cancer is still relatively rare.
But now all of the stomach-sparing Cox-2 inhibitors may pose a heart risk.
This could be the most competitive mass-market drug launch since the COX-2 anti-inflammatories Celebrex and Vioxx debuted in 1999.
The older drugs work by blocking two related enzymes called Cox-1 and Cox-2.
By only blocking Cox-2, the new drugs were supposed to spare the stomach.
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