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December 14, 1998
Like many arthritis sufferers, 69-year-old Peggie
Landvatter faces a daily dilemma. Should she endure the burning pain in her
hips and knees--or take her ibuprofen, and transfer the pain to her stomach?
"Every time I take something for the arthritis," she says, "it
aggravates the ulcer." Nearly a third of America's 40 million arthritis
sufferers use drugs like aspirin and ibuprofen to ease their joint pain. Taken
in large daily doses, these so-called NSAIDs (nonsteroidal anti-inflammatory
drugs) can make daily life bearable--or unbearable. An estimated 107,000 people
were hospitalized for NSAID-induced stomach ulcers last year, and 16,500 died
of complications from bleeding. But relief may be in sight. Last week advisers
to the Food and Drug Administration recommended approval of a new prescription
drug called Celebrex. The first in a new class of remedies known as Cox-2
inhibitors, it boasts the same pain-fighting power as other NSAIDs--yet studies
suggest it's as easy on the stomach as warm milk. Celebrex could reach the
market within the next few months, opening a new era in arthritis care.
To appreciate the beauty of the Cox-2 inhibitors, you need to understand how
the older NSAIDs work. Scientists discovered back in the 1970s that the drugs
handcuff an enzyme called cyclooxygenase--Cox for short. The body's Cox enzymes
normally metabolize a fat called arachidonic acid to generate inflammatory
hormones called prostaglandins. When a drug like aspirin knocks Cox out of
commission, it stalls the production of prostaglandins, dramatically reducing
pain and inflammation. The catch is that prostaglandins do more than make us
miserable. While some of them spark inflammatory reactions, others work quietly
to maintain the lining of the digestive tract. The question was how to suppress
the potential troublemakers while letting the housekeepers go about their work.
The answer came in 1991, when scientists isolated two distinct Cox enzymes.
Conveniently, one of them (dubbed Cox-1) seemed to govern the housekeeping
prostaglandins, while the other (Cox-2) specialized in pain and inflammation.
By screening hundreds of drug molecules, researchers led by Dr. Philip
Needleman of G.D. Searle Co. found one that bound selectively to Cox-2. The
result was Celebrex.
Because the new drug has 400 times more affinity for Cox-2 than for Cox-1, even
large doses have little effect on digestive tissues. When Searle researchers
snaked endoscopes into patients' stomachs, they found that 25 percent of those
taking traditional NSAIDs harbored small, harmless lesions. The incidence of
lesions was just 5 percent among Celebrex users, the same rate seen among
patients receiving a placebo. And whereas 2 to 4 percent of prescription NSAID
users suffer overt stomach problems, such as bleeding or ulcers, the rate of
such events was just 0.2 percent in Searle's studies. Peggie Landvatter, who
took part in a three-month Celebrex trial, found that the drug changed her
life. "There was no pain or discomfort," she says, referring to her
stomach as well as her joints. "I was doing things I'd put off for
years."
Gentle as the drug appears, the FDA's advisers stipulated that it should still
carry a warning about possible gastrointestinal problems. And they rejected
Searle's bid to market it as a general pain reliever, voting to approve it only
as a treatment for arthritis pain, pending further studies. Even so, analysts
foresee $3 billion in annual sales by 2001, and other companies are racing to
get in on the bonanza. Merck is now seeking approval for a Cox-2 inhibitor
called Vioxx; Glaxo Wellcome and Johnson Johnson are developing their own
versions.
Is the excitement a bit excessive? Many experts think so. Dr. Doyt Conn of the
Arthritis Foundation worries that patients will assume that Celebrex is all
they need, and abandon other efforts to control their conditions. "If you
have osteoarthritis in your knees," he says, "you can do more by
losing weight than by taking a pill." Other experts worry that people for
whom traditional NSAIDs are perfectly safe will start demanding the costly new
Cox-2 inhibitors, creating a needless drain on the health-care system. Some 96
percent of high-dose NSAID users don't develop ulcers, notes Dr. Thomas
Schnitzer of Northwestern University. "If you're an elderly person with a
history of gastrointestinal problems, the new drugs make sense," he says.
"If you're a 30-year-old athlete with a sprained ankle, why should an
insurer spend $4 to $5 a pill to get you the same relief you get safely for a
few cents?" The Cox-2 inhibitors will spawn many such dilemmas. But in the
meantime, they'll spare a lot of stomachs.
By Geoffrey Cowley With Esther Pan, Newsweek
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Inhouse Drugstore (UK)
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