Pfizer defends arthritis drug

People taking the arthritis drug Celebrex have a similar risk of suffering a heart attack or stroke as those taking Vioxx, which was withdrawn from sale last year, research has found.

A study by the New Zealand Intensive Medicines Monitoring Programme (IMMP), published in the international journal Drug Safety today, followed about 11,000 people prescribed either of the drugs during 2001.

Doctors supplied information about cardiovascular adverse events - heart attacks or strokes - their patients had after the drugs were prescribed.

But the study has come under attack by drug company Pfizer New Zealand, which has labelled it incorrect, misleading and "extremely irresponsible".

Principal investigator Dr Mira Harrison-Woolrych said of the 4882 patients taking Vioxx, 16 suffered a heart attack or stroke. A total of 37 adverse events were reported among the 6267 patients taking Celebrex.

Dr Harrison-Woolrych said the figures had to be adjusted to take into account the fact Celebrex patients were significantly older, had been taking the medication for longer, were more likely to be taking it for osteo-arthritis and to have had a pre-existing cardiovascular condition.

Once those factors were adjusted for it was found the risk of heart attack or stroke was similar, she said.

"It does contribute to evidence of a class effect. The Cox 2 inhibitor drugs all seem to have this effect."

Dr Harrison-Woolrych said while the group of 11,000 patients was reasonably large and clearly defined it may not be large enough to detect small differences in the rate of relatively uncommon events such as heart attacks and strokes.

Pfizer New Zealand spokesman Mark Crotty said the study went against the large body of data comparing cardiovascular risk between Celebrex and Vioxx. A US study of 1.3 million people found no increased risk associated with Celebrex.

"The 'study' referred to by the IMMP is simply an adverse events monitoring system and does not take into account individual cardiovascular risk. It is not a clinical trial, and its results should be treated with extreme caution."

Vioxx was withdrawn last year after a study found patients taking the drug were at twice the risk of having a heart attack or stroke as those on a placebo.

As a result Medsafe, the Ministry of Health's drug regulator announced it would review all the anti-inflammatory drugs, known as Cox 2 inhibitors. A final decision on the cardiovascular safety of the drugs is expected before the end of the month.

The ministry said yesterday that its advice remained that anyone with a history of heart disease or who was at risk of of heart attack or stroke, should not take Cox 2 inhibitor drugs.

The story so far

* Vioxx is withdrawn from worldwide sale in October last year after a study linked it to increased risk of heart attack and stroke.

* The Ministry of Health announces a review of all anti-inflammatory drugs known as Cox 2 inhibitors, including Celebrex.

* In February the ministry warns people taking one of five Cox 2 inhibitors - Celebrex, Arcoxia, Mobic, Dynastat or Bextra - to see their doctor about stopping the treatment because of the cardiovascular risks.

* This week Bextra is voluntarily withdrawn from the New Zealand market because of the potential increased risk of serious skin reactions.

* New Zealand monitoring study finds people taking Celebrex are at similar risk of heart attack and stroke as those taking Vioxx.