A drug used to treat thousands of patients in Britain for chronic pain in conditions such as arthritis has been linked with a doubling of the risk of heart attacks, according to a new study. The drug, Celebrex, is the third drug of its type to raise safety concerns.
Vioxx was withdrawn by its makers two years ago because of cardiovascular complications and Bextra was withdrawn last year because of skin reactions.
In 2004 about 2.5 million people were using Celebrex, but the numbers are known to have reduced substantially since concerns about the drugs were raised.
In the latest study, when researchers pooled the evidence from four existing studies which compared Celebrex with a placebo, they found that it was associated with a 2.26-fold increase in heart attacks.
The studies involved 4,422 patients who had taken the drug for at least six weeks.
A second analysis of 12,780 patients in six other studies suggested the drug gave a 1.88-fold increased risk of heart attack when compared with other pain killers including ibuprofen, paracetamol and diclofenac.
Celebrex, or celecoxib, is one of a class of drugs called Cox-2 inhibitors which were hailed as a breakthrough in the treatment of severe pain.
Traditional treatments like aspirin and ibuprofen are linked to stomach bleeding but the Cox-2s avoided this potentially serious side effect. Celebrex continues to be licensed for pain but doctors are advised to use the lowest effective dose, to avoid long term treatments and not to prescribe it for patients at risk of cardiovascular disease.
Some laboratory research has suggested that Cox-2s may create an imbalance that favours blood clotting and narrowing of blood vessels.
The latest study, in the Journal of the Royal Society of Medicine, adds to the debate over the safety of Cox-2s.
Prof Richard Beasley, of the Medical Research Institute of New Zealand, said yesterday: “Our evidence shows an increased risk of heart attack in patients taking celecoxib.
“Drug regulatory authorities urgently need to re-examine the assessment of the drug in light of these findings.”
A spokesman for the manufacturers, Pfizer, said the study sample was small and that the regulatory authorities had carried out extensive studies on Celebrex of their own.
“They were looking at a relatively small sub-set of data. We would point to the combined analysis by regulatory authorities that looked at 40,000 patients.
“This showed a risk similar to older therapies like ibuprofen.
”The other point was that the dose given was above the recommended dose for the majority of cases.”
The spokesman said many patients had been given an 800mg dose when the licensed dose is 200mg to 400mg daily.
Pfizer is starting a new long term trial of Celebrex.