The era of the COX-2 inhibitors appears to be coming to an end. Vioxx was removed from the market worldwide by Merck in September 2004. Pfizer has announced Celebrex is about to undergo new safety testing while the company’s other COX-2 inhibitor, Bextra, was removed from the market in April 2005.
The suspension of Bextra sales was due to safety concerns related to rare but serious skin reactions and cardiovascular problems. At that time, Health Canada issued a stop-sale order which ensured that Bextra (valdecoxib) would not be permitted to return to the Canadian market without further consultation with Health Canada.
The Canadian agency, which is the equivalent of the U.S. FDA, studied all of the available data on COX-2 inhibitors in general and concerning Bextra, specifically. Based on that review Health Canada has determined that “there is an increased risk of heart attack and stroke when these drugs are used for long-term treatment. Studies also showed that these side-effects can occur when Bextra is used for short-term pain relief following high-risk heart surgery. Bextra is also associated with a risk of rare but severe and potentially fatal skin reactions.”
The official announcement on the agency’s Web site (http://www.hc-sc.gc.ca/ahc-asc/media/advisories-avis/2005/2005_134_e.html) states: “The decision to stop the sale of Bextra is based on information submitted by the manufacturer, Pfizer Canada Inc., and consultations with external experts and the public. Health Canada concluded that there is insufficient evidence to establish the safety of the drug for its recommended use.”
“As a result of this regulatory action, the manufacturer will not be able to bring Bextra back onto the Canadian market under its present conditions of use. Health Canada has sent a letter to inform Pfizer Canada Inc. of the status of Bextra.”
The advisory concludes by stating that: “Health Canada has completed the review and agrees with the panel that available evidence indicates that COX-2 selective inhibitors and all other non-steroidal anti-inflammatory drugs are associated with an increased risk of cardiovascular events when high doses are used for long periods. However, the exact nature of that increased risk may differ from one product to another. The panel also found that the overall risk versus benefit profile for Bextra does not support the marketing of this drug in Canada under its current conditions of use.”