By: Steve Siwy for Knee1An advisory panel for the U.S. Food and Drug Administration voted on Feb.18 to recommend that doctors still be allowed to prescribe Vioxx, Bextra and Celebrex, painkillers known as cox-2 inhibitors, after studies had shown that patients using the drugs had an increased risk of heart attack.
Pfizer’s Celebrex received the strongest endorsement from the panel, which voted 31 to 1 to recommend that sales of the painkiller be allowed to continue. Bextra, also produced by Pfizer, and Vioxx, manufactured by Merck, were recommended by much narrower votes: 17 to 13 (with two abstentions), and 17 to 15, respectively. Merck had removed Vioxx from the market last September after one of their own studies showed that its use increased the risk of stroke and heart attack. Since then, other studies have shown similar risks for Celebrex and Bextra.
Still, the majority of the panel concluded that the use of cox-2 inhibitors, especially Celebrex, would still be appropriate for patients without a risk of cardiovascular disease. Dr. Michael Domanski of the National Institutes of Health, said in a Los Angeles Times article, “Clearly someone who is leading a poor quality of life [due to pain] and understands the risks is a good candidate [for Celebrex]. I don't think we should take this pill out of the hands of doctors."
Many news reports noted the panel’s recommendations would most likely lead the FDA to impose tighter restrictions on advertising for the cox-2 inhibitors, and would probably require the strongest kind of warning, known as “black box” warning labels, be carried on the drugs. Dr. Alastair Wood, the panel’s chairman, was quoted in The New York Times: "I think physicians need to be more thoughtful about how they use these drugs in the future. It would be a brave man or woman who started a patient with a clear history of heart disease on these drugs."
Cox-2 inhibitors are nonsteroidal anti-inflammatory drugs, also known as NSAIDs. NSAIDs work by blocking the enzyme cyclooxygenase, which reduces pain and inflammation by lowering levels of a lipid known as prostaglandin. There are two kinds of cyclooxygenase, both of which are blocked by traditional NSAIDs including ibuprofen or naproxen. This can cause gastrointestinal problems, but one of the types of cyclooxygenase, cox-1, also helps protect the stomach. The attraction for patients of cox-2 inhibitors over traditional NSAIDs is that they largely block the other kind, cox-2, and are easier on the stomach, a particular benefit for patients taking the medication for chronic conditions such as arthritis.
By blocking cyclooxygenase, however, cox-2 inhibitors lead to a reduction of a certain type of prostaglandin in the body that, while instrumental to the process of causing pain and inflammation, performs the additional function of protecting the cardiovascular system from another, damaging form of prostaglandin. The reduction in the “good” prostaglandin allows the “bad” prostaglandin to have a more negative effect on a patient’s heart.
The committee also recommended that labels on traditional NSAIDs be altered to warn that the long-term cardiovascular risks of these drugs is not yet known.
