The evidence is not conclusive, Pfizer executives say

The UK Department of Health said users of Celebrex, manufactured by US drug giant Pfizer, should consult their doctors before taking any action.

The US Food and Drug Administration (FDA) has yet to take any decision on the drug.

The latest findings came in one of two long-term cancer prevention trials.

The US National Cancer Institute (NCI), which conducted the study for Pfizer, said patients in the clinical trial taking 800mg of Celebrex had a 3.4 times greater risk of cardiovascular disease compared to those taking a placebo.

I don't think this one study, even though it is a large, well-controlled study, characterises the drug in any significant way Hank McKinnell Pfizer CEO

For patients in the trial taking 400mg of Celebrex, the risk was 2.5 times greater, it said.

In the study involving 2,000 patients, 15 individuals taking 400mg, 20 patients taking 800mg and six patients on placebo suffered either a cardiac-related death, heart attack or stroke.

In September, drug company Merck removed its arthritis painkiller Vioxx from the market for similar reasons.

Celebrex, Vioxx and three other drugs belong in the family of the cyclooxygenase-2 or COX-2 inhibitors - more "stomach friendly" alternatives to traditional pain relief drugs called non-steroidal anti-inflammatory drugs (NSAIDs).

The European Medicines Evaluation Agency is assessing the use of all of them.

Separate study

David Isenberg, from the British Society of Rheumatology, said "If you have no previous history of heart disease and you have been on Celebrex or any similar drugs for a short period of time it seems very unlikely that you have anything to worry about.

"The greater concern would come if you have a history of heart disease and you have been on these drugs for more than a year."

The NCI suspended the use of Celebrex following the results of the study, news of which sent Pfizer shares tumbling on Friday.

Pfizer says it has no plans to withdraw the drug, used by an estimated 26 million arthritis patients.

A separate cancer study done by the drug company suggested patients taking 400mg of Celebrex per day had no increased heart risk.

Pfizer chairman Hank McKinnell said he had no intention of withdrawing the drug at this stage.

"I don't think this one study, even though it is a large, well-controlled study, characterises the drug in any significant way," Mr McKinnell told CNBC television.

Acting FDA Commissioner Lester Crawford said the agency was not taking any regulatory action at present.

But he added: "We do have great concern about this product and the class of products."