There is no evidence to back up claims that the new generation of anti-inflammatory drugs (COX-2 inhibitors) are less harmful to the stomach lining than many traditional anti-inflammatory drugs.

That is the claim of a new study, published in the British Medical Journal by researchers at the University of Nottingham in the UK. Evidence of enhanced gastrointestinal safety with any of the new COX-2 inhibitors compared with non-selective non-steroidal anti-inflammatory drugs is lacking, they say.

The finding adds to the pressure on the COX-2 inhibitor class, which quickly achieved blockbuster status after launch on the promise of reduced GI damage compared to conventional NSAIDs. But they are now in decline, mainly as a result of the much-publicised withdrawal of Merck & Co’s Vioxx (rofecoxib) on safety grounds. Although other COX-2 inhibitors, notably Pfizer’s Celebrex (celecoxib) – remain on the market, sales have suffered on the back of fallout from Vioxx.

The UK team examined records involving more than 9,400 patients in the UK with a first ever diagnosis of an upper gastrointestinal event (stomach ulcer or bleed), and looked at prescriptions for anti-inflammatories or aspirin in the three years beforehand. Each case was matched with up to 10 control patients.

They found increased risks of adverse GI events were associated with current use of COX-2 inhibitors and with conventional NSAIDs. Risks were reduced after adjusting for other factors, but remained significantly increased for naproxen, diclofenac, and rofecoxib, but not for current use of celecoxib.

The use of ulcer healing drugs reduced the risk with all groups of non-steroidal anti-inflammatory drugs, although for diclofenac the increased risk remained significant.

These results suggest that COX-2 inhibitors may not be as safe as originally thought, although a possible confounding effect cannot be ruled out, conclude the researchers.