The US Food and Drug Administration is to bring together an arthritis advisory panel to review Merck & Co’s painkiller Arcoxia (etoricoxib) and decide whether to give it the green light of approval for treating the signs and symptoms of osteoarthritis. It will be a well-watched meeting, following as it does in the wake of strenuous criticism levied at the agency after Merck’s multi-billion-dollar forerunner Vioxx (rofecoxib) was pulled off the market in 2004.

Arcoxia belongs to the same class of COX-2 inhibitors as Vioxx, but is already marketed in a number of countries around the world, and Merck is hoping that the extensive clinical research it has conducted into the drug will help it overcome the likely intense scrutiny over drug safety that will arise.

Specific COX-2 inhibitors were once thought of as a panacea to the gastrointestinal problems linked to use of non-steroidal anti-inflammatory drugs. However, some years later – and many billions of dollars richer – most companies, with the notable exception of Pfizer’s Celebrex (celecoxib), were forced to pull their products from the market after a raised risk of heart attack and stroke was observed. Despite being the only COX-2 on the US market now, Celebrex initially saw a steep decline in sales but the tide may be turning and – as well as Arcoxia – Novartis also hopes to seek a US nod for its offering Prexige (lumiracoxib) this year.

Last November, Merck unveiled a clinical trial indicating Arcoxia was as safe as the older NSAID drug diclofenac in terms of its cardiovascular risk profile, but the data were immediately criticised by cardiologists who said the choice of comparator drug was flawed. Steven Nissen of the Cleveland Clinic in Ohio pointed out that diclofenac is widely-regarded as being particularly prone to thrombotic side effects, so its use as a comparator limits any safety conclusions that can be drawn for Arcoxia. However, this didn’t stop Arcoxia from reeling in $265 million in 2006.

Merck originally withdrew its marketing application for Arcoxia in the USA in 2002, at a time when concern over the tendency of COX-2 inhibitors to cause heart attacks and strokes was starting to build. The company re-filed the application in 2003, but the agency requested more safety information in 2004.

The Arcoxia meeting has been scheduled for April 12 and Merck is expecting a decision on approvability by the end of that month.