Printed Reports Verify Fears About Cox-2 Inhibitors
Data back years-old warnings tying pain relievers to heart ailmentsFeb 16, 2005 | www.nj.com
Six years after a class of pain relievers called Cox-2 inhibitors were approved for use by millions of Americans, a prestigious medical journal yesterday published the results of three large clinical trials showing that those using the drugs are doing so at risk to their hearts.
Released on the eve of a rare FDA public hearing in Maryland into the safety of the Cox-2s, the studies and results that seem to come six years too late confirm the belief among many industry watchers that the system set up to protect the public from unsafe drugs is falling apart.
"There is a sense that things are broken," said Bruce Psaty, a physician-researcher at the University of Washington and a co-author of an editorial criticizing the FDA and drug makers in the latest New England Journal of Medicine. "There's been a studied inattention to safety during the last decade." The American people, he said, are beginning to see the results in cases like this.
Though reports about the studies have circulated for months, the three trials that led to questions about Cox-2 inhibitors, including Merck's Vioxx, and Pfizer's Celebrex and Bextra, are described in print for the first time.
The drug companies submitted safety data, based on six-month studies, nearly a decade ago in order to get the drugs approved by regulators. The heart ailments, it turns out, often do not occur until a patient has been on the drug for about a year.
Drug industry critics such as Sidney Wolfe of Public Citizen in Washington, D.C., point out there were warning signs on Vioxx and Celebrex as early as four years ago, but the FDA ignored them.
"The FDA dangerously fell down on the job," he said. He also faulted Pfizer for not disclosing negative results from a study until recently.
FDA officials say they have not turned their back on safety, but have been responding to demands by industry and Congress to speed up drug approvals. Drug industry leaders insist they have lived up to the letter of the law. Officials at Merck and Pfizer did not return calls for comment.
"The whole system needs to be looked at," said Sheldon Krimsky, a Tufts University professor whose book, "Science in the Private Interest" documents conflicts of interest between regulators and pharmaceutical representatives. "Until we have a firewall between the manufacturers of drugs and the people who test them, we're going to continue to see these problems, regardless of putting more people in the FDA or trying to be more transparent."
One thing business leaders, federal regulators and academics agree on, however, is that no one is happy that the safety of the popular drugs is being questioned.
"Physicians are dismayed, pharmaceutical companies are embarrassed and financially threatened, and patients are injured," wrote Psaty and Wake Forest University physician-researcher Curt Furberg in the New Egland journal. "Indeed, the integrity of the American drug-safety system has been questioned."
It wasn't supposed to happened this way.
Cox-2 medications were regarded as wonder drugs when they were developed in the 1990s.
Their discovery grew out of research on aspirin and aspirin-like drugs, a class of treatments that reduce the signs and symptoms of inflammatory diseases without eliminating the underlying causes.
The search for how the drugs work showed that aspirin and similar drugs curtailed production of chemical messengers called prostaglandins, which cause the pain and inflammation in autoimmune diseases such as arthritis. Looking further, scientists discovered cyclooxygenase, a protein nicknamed "Cox," that spurred the production of prostaglandins.
Ultimately, researchers found there were actually two such proteins and dubbed them Cox-1 and Cox-2. Cox-1 produces a prostaglandin that protects the stomach lining against irritation. Cox-2 controls the inflammation reaction.
Older drugs, such as aspirin, inhibited both proteins but left the stomach lining at risk for irritation. The newer drugs, however, suppress only Cox-2, leaving Cox-1 available to protect the stomach.
However, scientists now believe that the Cox-2 protein, though it provokes inflammation, also has a positive effect on the body by protecting it against hardening of the arteries. According to a study published in Science in November, the Cox-2 protein and estrogen interact to produce a fatty acid called PG12, which limits the supply of blood platelets that can cause clots and damage artery walls. This means Cox-2 inhibitors may be suppressing some vital protection against heart disease.
Merck voluntarily pulled Vioxx from the market overnight in September after learning from studies that there was a statistically increased risk of heart attack and stroke in study participants taking the arthritis drug. Weeks later, Pfizer revealed that Bextra had been linked to heart problems in another one of the now-published studies.
In December, the company referred to the results of the third study when it said a long-term cancer study showed that those taking Celebrex increased their risk for heart attacks and strokes. The company has since stopped advertising the drugs.
"No drug is ever brought to market without being an experiment on the public," said Krimsky of Tufts. "The real issue is that we have to pay more attention to adverse events. We have to be serious about looking hard for them."