Canadian and British researchers are calling for the anti-inflammatory diclofenac to be pulled from the market worldwide because of its heart risks.
Diclofenac is sold under a variety of brand names including Voltaren and is widely used for pain such as headaches, toothaches and arthritis. The pills are available with a prescription in Canada and over-the-counter elsewhere in the world.
Writing in Tuesday's issue of the journal PLOS Medicine, published by the Public Library of Science, Dr. David Henry of the Institute for Clinical Evaluative Sciences in Toronto ranked the cardiovascular risks and sales of non-steroidal anti-inflammatories, or NSAIDs, in 15 countries including Canada, Australia, China, Pakistan and Vietnam.
"This is a drug that has about the same risk of causing heart attacks as a drug called Vioxx, which was withdrawn from the market eight years ago because of this adverse effect," Henry, who is also a clinical pharmacologist, said in an interview with CBC News.
"We believe there’s no advantage over safer drugs, and we believe it should be withdrawn from world markets."
Despite having an equivalent cardiovascular risk to Vioxx or rofecoxib, diclofenac remains popular in many countries, with more than a third of the market for NSAIDs worldwide and about 15 per cent in Canada, Henry said.
Henry advised against diclofenac in favour of safer NSAIDs such as naproxen for people with risk factors for heart disease such as high cholesterol or a history of heart disease. For those who have a low risk of heart attacks, diclofenac does not increase the heart risks to any great degree.
Appeal to agencies
Several studies, including a previous paper by Henry, have found diclofenac may increase the risk of heart attacks and strokes in rare cases.
Since those publications, Henry said he's appealed to regulatory agencies. He and co-author Patricia McGettigan of Barts and the London School of Medicine and Dentistry in London, U.K., are now publicizing the risks to consumers directly.
Pharmaceutical expert Muhammad Mamdani, director of the Applied Health Research Centre at St. Michael's Hospital in Toronto said NSAIDs also carry gastrointestinal and kidney risks.
"I think in the broad spectrum of things … we need to balance what these drugs do, what the side effects are, and what types of patients are getting it," Mamdani said.
Europe's drug regulator is reviewing the cardiovascular safety of diclofenac. Health Canada hasn't said if it will.
It's thought that non-selective NSAIDs like diclofenac that don't block the COX-1 enzyme completely can cause an imbalance in prostaglandins that increase the risk of blood clotting, Ambuj Roy of the cardiology department at the All India Institute of Medical Sciences in New Delhi said in a journal commentary accompanying the study.
Roy agreed there's a strong case for removing diclofenac from national lists of government-approved drugs and that the World Health Organization should explain why NSAIDs are included and excluded from its list.