In a Nature Reviews of Drug Discovery article this month the researchers from Imperial College London and Queen Mary, University of London examine the use of selective inhibitors of cyclo-oxygenase-2 (COX-2).
They argue that although this class of drugs, which includes Vioxx, has been associated with an increase in the risk of cardiovascular events such as heart attacks and strokes in some patients, the same may be true for traditional non-steroid anti-inflammatory drugs (NSAIDs).
All NSAIDs, including COX-2 inhibitors, work by blocking the actions of both COX-1 and COX-2 enzymes. Blocking COX-2 relieves inflammation and pain, but blocking COX-1 can increase the risk of gastric ulcers and bleeds. For this reason COX-2 selective drugs were developed with the simple aim that they would retain the therapeutic actions of NSAIDs (linked to inhibition of COX-2) but lose the gastric side effects (linked to inhibition of COX-1).
The researchers reviewed over one hundred papers on the subject and looked at the latest recommendations from organisations such as the American Federal Drugs Administration on the use of COX-2 inhibitors and NSAIDs.
The researchers point out that the calls for the removal of COX-2 inhibitors, and a return to using NSAIDs, may cause additional problems. Although NSAIDs have been marketed for a number of years, they have never been required to meet the clinical trial standards now set for COX-2 inhibitors, meaning they may not be any safer.
Professor Jane Mitchell, from Imperial College London, and one of the reviews authors, said: "Although some COX-2 drugs have been reported to increase the risk of heart attack and stroke, they may still remain the best option for treating arthritis in some patients without cardiovascular risk factors who cannot tolerate traditional NSAIDs because of gastric side effects."
Professor Mitchell added: "This review shows us that despite the large scale use of NSAIDs and COX-2 inhibitors for a number of years, we still need more information on their benefits and potential risks and that more research needs to be done in this area. Looking at existing evidence, however, it would seem COX-2 inhibitors may be the best option for some patients. They are as effective as traditional NSAIDs, but with less gastric side effects than some older drugs."