Health Canada lukewarm on Vioxx panel findings

Figure. The rofecoxib molecule. Photo by: dominionpaper.ca

An expert panel is recommending the reintroduction of rofecoxib (Vioxx) on the Canadian market, but Health Canada is unsure about some of the panel's evidence and won't make a decision until fall.

Rofecoxib, a COX-2 inhibitor, was voluntarily withdrawn worldwide by manufacturers Merck & Co. in September 2004 after a study showed patients taking the drug on a long-term basis face twice the risk of a thrombotic event compared with patients receiving placebo (N Engl J Med 2005;352[11]:1092-102).

The panel, convened by Health Canada, examined data from a wide range of sources, including a new meta-analysis of 138 studies on the cardiovascular risk of COX-2 inhibitors by researcher Dr. Colin Baigent.

Dr. Marc Berthiaume, Director of the Marketed Pharmaceuticals Division at Health Canada, is not sure about the results. “Some of the choices [Baigent] made can have skewed some of his findings: he lumped together short- and long-term findings for patients on NSAIDs.” Berthiaume says Health Canada hasn't taken an official position on the study.

In defence of his study, Baigent, a senior scientist at the Clinical Trials Service Unit at Oxford University, says that “ideally we'd like individual patient data … . When you've only got tabular results you can only group the short-term and long-term studies together.” He adds, “What we desperately need is to have the data publically available.” The study is being considered for publication in a peer-reviewed journal.

The expert panel chair, Dr. Andreas Laupacis, said the paper is “one of the highest quality of systematic reviews we've seen.” Dr. Claire Bombardier, lead author on the Vioxx Gastrointestinal Outcomes Research (VIGOR) study, hasn't seen the whole study but says it offers “strong evidence and a balanced view.”

If the panel is correct, was Merck's decision to withdraw rofecoxib premature? Berthiaume doesn't think so. “Their decision was based on the safety information available and it was a good decision,” he says. Merck Frosst Canada spokesperson Marlene Gauthier agrees: “At the time there seemed to be alternatives that had less risks.”

Reintroducing rofecoxib to the market now depends on Merck Frosst's willingness to resubmit the drug for approval and on Health Canada's approval, which could take 2–18 months.

Some patients are clamouring for the drug to be reintroduced, says Bombardier. Laupacis concurs: “Rheumatologists find some people respond to some drugs and not the others … they want choice.”

While Health Canada debates what to do about rofecoxib, legal proceedings are going ahead, says lawyer Tony Merchant of Regent-based Merchant Law Group. At least 7 suits have been filed, including a 7-province action filed in the Federal Court of Canada naming the federal government as co-defendant.

Merchant believes that the failure to disclose and label rofecoxib properly was the equivalent of failure of informed consent for patients involved.

Merck plans to defend itself on a case-by-case basis.