Successor to Vioxx fails to quell concerns

When drug company Merck revealed the the results of a study this week over it's successor to Vioxx, the new arthritis drug Arcoxia, it did little to quell concerns about both the use and the safety of the new drug.

Both Vioxx and Arcoxia are painkillers known as Cox-2 inhibitors; Vioxx was withdrawn from the market in September 2004, after a study found it doubled heart attack and stroke risks.

In the largest-ever trial of an arthritis drug, researchers tested Arcoxia against an older treatment, the generically available diclofenac and gathered data from three trials involving almost 35,000 patients with osteoarthritis and rheumatoid arthritis.

The study looked at patients aged 50 or older who were treated for an average of 18 months.

Since their initial appearance in 1999, Vioxx and other Cox-2 drugs such as Pfizer's Celebrex and Bextra had been lauded as super aspirins which were better and safer than older painkillers.

The drugmakers promised they would ease pain without causing serious stomach bleeding and ulcers, an effect of common drugs known as non-steroidal anti-inflammatory drugs (NSAID's) such as ibuprofen, naproxen and diclofenac.

Merck is chasing U.S. approval for Arcoxia (etoricoxib), and has been comparing its effects to those of the NSAID's.

In a presentation at the American Heart Association annual meeting, Merck said its 35,000-patient programme, called Medal, found that Arcoxia had similar heart risks to diclofenac, a NSAID and has forwarded the the data which is also published in The Lancet – to the Food and Drug Administration (FDA).

The Medal study found that Arcoxia had fewer ulcers associated with its use than diclofenac, but just as many complicated ulcers and more blood pressure side effects.

However, experts dispute the claims and say that the study offers little new information and is essentially flawed.

They say diclofenac was not the best comparison drug for Arcoxia as the two drugs are too similar in how they behave and a better comparison would have been to compare Arcoxia with ibuprofen or naproxen, which are more commonly used and act differently, with potentially less heart risk than Merck's drug.

The experts suggest that enough is already known about the relative risks of such drugs and the money could have been better spent elsewhere.

The debaucle over Merck's withdrawal of Vioxx, also forced Bextra off the market and prompted greater public scrutiny of drugmakers' analysis of risks and benefits, and of U.S. drug safety regulation and consumer advertising of medicines.

Merck is currently facing almost 24,000 lawsuits over Vioxx.

Arcoxia has been approved in 62 other countries, including the UK.