[David Graham] says he would also like to see the FDA pull diclofenac off the market. Diclofenac and Arcoxia are both non-steroidal anti- inflammatory drugs, or NSAIDs. Some recent analyses have concluded that diclofenac is the riskiest of the older NSAIDs. In a large trial, Merck compared Arcoxia with diclofenac and found similar heart attack and stroke rates.

Graham says Merck should have compared Arcoxia with naproxen. Merck's largest test of Vioxx was against naproxen, and it found five times more heart attacks in the Vioxx group. However, the FDA requires all NSAIDs to carry the same warning about heart attack and stroke risk. "The label for naproxen should say it appears to be the safest NSAID with respect to cardiovascular risk," Graham says. "They're not all the same."