Animal Research on Trial: PCRM Sues Merck over Vioxx Animal Tests
When PCRM member Nancy Tufford began taking Vioxx in January 2002, she had no idea that Merck, the drug’s manufacturer, was betting her life on a misleading animal experiment. The drug giant—eager to keep a profitable drug on the market—had decided to rely on tests showing that Vioxx was safe in mice, rats, and monkeys, while ignoring mounting evidence that the drug was dangerous to humans.
The healthy and active Minneapolis resident first took the painkiller after injuring her shoulder at the local YMCA and stuck with it because it seemed to help her arthritis. A little over a year later, Tufford began experiencing fatigue and shortness of breath. A nonsmoker who had no symptoms or history of heart problems before taking Vioxx, Tufford was diagnosed with congestive heart failure in the summer of 2004.
An estimated 140,000 Americans developed heart and vascular disease from Vioxx. What makes Tufford’s case unusual is that she—with help from PCRM—is taking Vioxx’s manufacturer to court over its reliance on misleading animal tests.
Tufford is a plaintiff in a PCRM lawsuit against Merck & Co. filed in July in the Superior Court of New Jersey. The suit charges that the New Jersey-based pharmaceutical maker wrongfully relied on animal tests while ignoring more applicable human data.
The PCRM case is believed to be the first time a U.S. pharmaceutical company has been sued specifically for relying on animal tests. A top-selling painkiller, Vioxx was pulled off the market in fall 2004, after results from a clinical study showed that the drug doubled the risk of stroke and heart attack in humans.
• More than 100,000 Americans die each year from adverse reactions to approved drugs. This is the fifth leading cause of death in the United States.
• More than 90 percent of drugs that appear safe in animal tests fail in human studies.
• More than half of all approved drugs will be withdrawn or relabeled for serious or lethal effects in humans.
Animal Tests Led Merck Astray
PCRM cardiologist and medical researcher John J. Pippin, M.D., F.A.C.C., testified before Food and Drug Administration and Institute of Medicine committees on drug safety and released a major report on the failure of animal tests to predict Vioxx’s dangers.
According to Dr. Pippin, Merck disregarded and suppressed human risk data that began appearing in 1996—and continued to do so after its own study in 2000 showed that Vioxx was linked to five times the heart attack risk of naproxen, an older anti-inflammatory drug. Merck used data from animal tests to make a case for keeping its blockbuster drug on the market.
Nine of 11 studies on mice and rats had shown Vioxx or other COX-2 inhibitors to be safe for animal hearts and blood vessels. In fact, six different animal studies—in four different species—showed Vioxx was actually protective against heart attacks and vascular disease. One researcher went so far as to suggest that Vioxx be considered a treatment for human cardiovascular disease, based on these animal tests.
Monkey tests were a special problem. After human studies indicated that Vioxx was more dangerous than another painkiller, naproxen, Merck used experiments on African green monkeys to try to show that Vioxx wasn’t the problem. The monkey tests showed that Vioxx was neutral for the heart, while naproxen seemed to have a special heart-protective effect. Merck’s falsely optimistic animal tests led the company to disregard the deadly problems emerging in humans.
PCRM’s lawsuit charges that Merck was well aware of the limitations of animal testing—that animal experiments are often inconsistent, species-dependent, and not useful in predicting drug safety or efficacy in humans.
Vioxx Reflects Larger Problem
Because most animals don’t suffer from heart attacks, hypertension, and other cardiovascular problems, Merck and other drug companies have used artificial methods to attempt to mimic heart disease in animals. In the study on African green monkeys, Merck researchers used electrical shocks to damage the animals’ veins and arteries and induce blood clotting.
The end result of such tests was a large collection of unreliable data. In this respect, Vioxx is not unique. Many other drugs have appeared safe in animal tests but proved dangerous in humans. Rezulin, a diabetes drug, appeared safe in rats, but caused fatal liver failure in humans. The opposite scenario is also common. Penicillin, for example, was discovered in 1929 but not used until a decade later because of its ineffectiveness in curing infected rabbits. If it had been tested in cats, guinea pigs, or hamsters, penicillin would likely have been abandoned as toxic.
Merck erred in not doing adequate post-market surveillance of patient reactions, says Dr. Pippin. And the company should have conducted in vitro tests using human cells and tissues, along with extensive computer modeling, rather than animal tests. PCRM’s lawsuit charges Merck with knowing of these methods but failing to employ them.
“Merck was wrong to rely on data from mice, rats, and African green monkeys when faced with compelling evidence that human patients were at risk,” says Dr. Pippin. “Animal trials didn’t predict that Nancy Tufford would develop heart disease from Vioxx, but human trials clearly did. Until we stop using animal tests to gauge the safety of human drugs, disasters like Vioxx are inevitable.”
PCRM president Neal D. Barnard, M.D.
PCRM attorney Dan Kinburn
Muhammad Mamdani, Pharm.D., M.A., M.P.H., lead author of human-based study linking Vioxx to congestive heart failure
PCRM cardiologist and medical researcher John J. Pippin, M.D., F.A.C.C.