Arthritis DRUGS Vioxx or Celebrex may up heart attacks

[Guest guest]

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Steven Powers MD.

 

Sunday, April 21, 2002 12:40 PM

Arthritis DRUGS Vioxx or Celebrex may up heart

attacks

 

 

- http://www.canoe.ca/Health0204/18_arthritis-ap.html -

 

 

Arthritis drug may up heart attack risk

 

 

 

By LAURAN NEERGAARD -- Associated Press

 

 

WASHINGTON (AP) -- New research bolsters the growing suspicion that some popular

arthritis drugs could increase certain people's risk of heart attacks by causing

a chemical imbalance that spurs blood clots.

 

The study of the new painkillers, called cox-2 inhibitors, was done in mice. The

evidence it uncovered is so strong that the University of Pennsylvania

researchers plan to study human users of the drugs to determine if their hearts

truly are at risk.

 

The concern is for people with heart disease -- not healthy people -- who take

Vioxx or Celebrex, touted for their ability to relieve arthritis pain without

the stomach upset of aspirin and other painkillers.

 

Last summer, a study found certain Vioxx users suffered twice as many heart

attacks and other cardiovascular problems as users of the older painkiller

naproxen.

 

The new study by the Penn researchers, in Friday's edition of the journal

Science, provides a biological explanation for how the drugs could cause such

side effects by spurring blood clots.

 

The drugs' makers dismissed the new study as irrelevant and said their products

pose no risk.

 

But one leading heart expert called the Penn research an important key that

shows it's time for a prompt study of the drugs' users.

 

" Now the only thing we're really missing is quantifying the magnitude of the

risk, " said Eric Topol, chairman of cardiovascular medicine at the Cleveland

Clinic. " This is a major public health question because so many millions of

people take these cox-2 blockers. "

 

For now, he said, " If you have heart disease, it ought to be with particular

care and concern that you take these medications, ... because there could be

some risk. "

 

Human bodies harbor two forms of an enzyme that plays a role in pain-causing

inflammation and blood clotting. One form, cox-1, makes thromboxane, which

causes blood vessels to constrict and platelets to become sticky, important

steps in a heart attack or stroke. The other, cox-2, is a major source of

prostacyclin, which dilates blood vessels and prevents platelets from clumping

together.

 

In a healthy person, the two coxes are thought to balance each other so blood

doesn't excessively clot.

 

Aspirin significantly cuts the risk of a heart attack because it thins the blood

by blocking cox-1; it also slightly blocks cox-2.

 

Vioxx and Celebrex, in contrast, block only cox-2, which some researchers

believe could allow cox-1's clotting tendencies to run amok. The drugs' makers

have long dismissed that idea, because other body chemicals also play a role in

clotting.

 

Then the Vioxx-vs.-naproxen study made headlines last summer. Vioxx maker Merck

& Co. argued Vioxx didn't cause heart illness, but that naproxen thinned the

blood, giving its users an extra benefit.

 

The new Penn study suggests cox-2 blockers may actually play an active role.

 

In genetically engineered mice, researchers irritated an artery to spur release

of both clotting chemicals. Mice resistant to prostacyclin's effects -- a model

of cox-2 inhibition -- experienced more thromboxane-caused clotting activity.

 

That's not proof people would be endangered, stressed pharmacologist and lead

scientist Garret Fitzgerald. Still, " the credibility of the hypothesis is

enhanced " enough that he plans human studies.

 

Merck scientist Alise Reicin said the study added no new information to the

debate, particularly because it used mice with completely inhibited prostacyclin

while cox-2 drugs inhibit the chemical half as much.

 

She said Merck plans further safety studies, but refused to provide details.

 

Celebrex maker Pharmacia Corp. also dismissed Fitzgerald's study, saying there's

no sign of a problem among Celebrex users.

 

There's no concern for heart-healthy people, but the drugs have never been

properly tested in people who do have heart disease, Fitzgerald said.

 

Asked if people could hedge their bets by taking a heart-friendly aspirin along

with Vioxx or Celebrex, Fitzgerald said there's no data showing that would work,

and the aspirin could cause stomach upset.

 

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