Novartis’ problems with its new-generation COX-2 inhibitor Prexige continue to pile up with the news that the treatment has been withdrawn from the Canadian market, at the behest of the country’s regulator.

Health Canada has stopped the sale of Prexige (lumiracoxib) and will cancel the drug's market authorisation due to the potential for serious liver-related adverse events. It has been marketed in Canada since November 2006 for the treatment of osteoarthritis in adults at a maximum daily dose of 100mg.

The regulator had asked Novartis to provide additional safety information after Prexige was removed from the Australian market in August following reports of serious liver adverse events that were linked to the drug at doses of 200mg and 400mg daily. Health Canada said that “the experience of other international regulators is a potential source of safety signals for new drugs when the Canadian real world safety information is limited” and after having conducted a review, it has decided that the risk of taking Prexige “cannot be safely and effectively managed at the 100 mg daily dose” either.

The agency noted that there have been two Canadian cases of serious liver-related adverse events associated with the use of Prexige, making a total of four cases internationally.

The Canadian withdrawal comes a week after the US Food and Drug Administration issued a ‘not approvable’ letter for Prexige, a move which seemed to surprise Novartis somewhat, seeing as it produced a clinical trial database “that comprises approximately 40,000 patients and is one of the largest bodies of evidence for any of the drugs in this class”. However, the whole COX-2 class has been treated with suspicion since the 2004 withdrawal of Merck & Co’s blockbuster Vioxx (rofecoxib) and in the wake of the Australian decision to pull Prexige, healthcare regulators in Europe imposed restrictions on the drug over fears that it may cause serious liver damage.