Diclofenac, a popular painkiller sold as Voltaren and other brand names, is as risky as Vioxx and should be taken off the market, Canadian researchers warn.
However, in the absence of action from Health Canada, researchers are taking the unusual step of asking patients to stop taking the drug and turn to safer alternatives, such as naproxen.
"[Diclofenac] is symptom relieving. You can buy alternatives over the counter without a prescription," said David Henry, chief executive officer of Toronto's Institute for Clinical Evaluative Sciences and professor of medicine at the University of Toronto. "Don't wait for your doctor to take you off it. Take yourself off it."
Henry is the co-author of a study published this week in the journal PLos Medicine that found certain non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of heart attack and stroke in people with diabetes, high cholesterol, previous heart attack or other factors that put them at high risk for cardiovascular problems. NSAIDs are widely prescribed to relieve pain associated with arthritis, muscle injuries and other conditions.
Diclofenac is believed to be the most commonly prescribed NSAID in the world. Although it's not the most popular in Canada, it is among the more commonly prescribed NSAIDs in this country. About 1.3 million prescriptions for diclofenac were dispensed from Canadian retail pharmacies in 2009.
The study published this week analyzed data from previously published studies of NSAIDs. The researchers concluded that diclofenac comes with substantial risks and should not be taken by people in danger of heart problems.
Another drug, etoricoxib, which isn't available in Canada, is also singled out as risky. The study highlights research that found people taking etorixocib faced double the cardiovascular risks compared with people not on the drug. However, the heart risks linked to etoricoxib have not been as well established as that of diclofenac.
Vioxx is an infamous member of the NSAID class. In 2004, it became a cautionary tale for regulators when it was pulled in the market after studies confirmed that it increases the risk of heart attack and stroke. After that controversy, researchers began taking a closer look at other NSAIDs and found that some also carry a high-risk profile.
Henry, as well as other researchers around the world, have since concluded that diclofenac poses serious risks and should be removed from the marketplace.
Despite repeated calls over several years to stop the use of diclofenac, he said, he does not have much hope that Health Canada or other regulators will take decisive action. Part of the problem is that diclofenac is off-patent, which means it is produced by a number of manufacturers. This makes it harder to single out one company and apply pressure for the removal of the drug.
Health Canada was unable to respond to questions about the status of diclofenac and whether it is conducting any safety reviews.
At the same time, diclofenac has been around for so long and is so widely used that it may simply be hard to break the habit. "That familiarity breeds a certain complacency about the drug," Henry said.
Now, he and his colleagues plan to lobby the World Health Organization to have naproxen listed on "essential medicines" lists around the world instead of diclofenac. Countries use these lists to prioritize which medicines they need to satisfy the health-care priorities of the population. Last October, the European Medicines Agency launched a review of the cardiovascular safety of diclofenac.