Renewed fears about the safety of arthritis drug Celebrex have been raised after scientists linked it to an increased risk of heart attacks.
There are already safety concerns about this family of drugs
A Journal of the Royal Society of Medicine study suggested those on the drug had double the heart attack risk.
Celebrex is in the same drug family as Vioxx, withdrawn from sale last year.
Arthritis experts said Celebrex offered the best pain relief for some, while makers Pfizer said a larger study found it was as safe as other painkillers.
Like Vioxx, Celebrex is a Cox-2 inhibitor, which have fewer side-effects on the digestive system than other common painkillers such as ibuprofen.
In 2004 at least 600,000 patients were prescribed Celebrex - which is the brand name for celecoxib - in the UK.
But doctors are now advised not to give it patients with a heart condition or stroke.
Vioxx was voluntarily withdrawn from world markets by drug firm Merck after research linked it to an increased risk of heart attacks and strokes.
Professor Richard Beasley, from the Medical Research Institute of New Zealand in Wellington, carried out this latest research in an attempt to discover if patients on Celebrex faced any similar risks.
After pooling together and analysing data from six trials involving almost 13,000 patients, he concluded that patients on the drug faced double the heart attack risk.
He said: "Drug regulatory authorities need urgently to re-examine the assessment of the drug in light of these findings."
Four of the studies comparing Celebrex with a "dummy" placebo found patients taking the drug were 2.26 times more likely to suffer a heart attack as those who were not.
When Celebrex was compared with other painkillers like ibuprofen and paracetamol, all six of the studies found the heart attack risk was raised 1.88-fold.
Professor Beasley said his findings were critical because the risk was similar in magnitude the 2.24-fold risk of heart attack linked to Vioxx.
Manufacturers Pfizer said: "Patients taking Celebrex had no more risk for heart attack, stroke, or CV (cardiovascular) death combined than those given non-selective non-steroidal anti-inflammatory drugs (NSAIDs)."
It pointed to a much larger study of 44,000 patients, pooling data from 40 clinical trials, which found those taking Celebrex were at no greater risk of heart attack than patients on traditional painkillers such as ibuprofen.
A spokesman for Arthritis Care said: "All drugs carry risks and benefits.
"People who experience severe pain as a result of their arthritis will need to balance the possible risk from particular drugs against the benefits taking them could bring.
"We would urge anyone worried about this latest study to consult their GP."
An Arthritis Research Campaign spokeswoman added: "Many GPs and hospital consultants stopped prescribing Celebrex after the withdrawal of Vioxx in September 2004.
"This latest evidence may now prompt drug regulators to re-consider and think about taking the drug off the market.
"It means that there is less choice for people with arthritis, but patient safety is paramount."
Professor Peter Weissberg, medical director of the British Heart Foundation, said: "There has always been a question over the safety of these drugs. Their reputation is already tainted and GPs are all aware of the risks.
"But some people live with appalling pain.
"If they know that the attack doubles their risk of heart attack - but their personal risk of heart attack is low - this is a risk they will take in order to get a drug which really does help them.
He added: "Which is worse - the pain of the condition or the increased risk of heart problems?"