Celebrex is one of a class of painkillers that selectively block the COX-2 enzyme, which is linked to inflammation. Other NSAIDS such as aspirin and naproxen affect both COX-1 and COX-2, and the COX-2 drugs were designed to be more specific and thus safer.
Merck & Co. Inc pulled its COX-2 inhibitor, Vioxx, from the market in 2004 after studies showed it raised the risk of heart attacks and strokes in long-term users. Pfizer withdrew a similar drug, Bextra, but has continued to market Celebrex.
The latest study was ended early because of the heart attack and stroke concerns about this class of drugs.
