The world's largest class action lawsuit has been launched in the US

The world’s largest class action lawsuit has been launched in the US by patients seeking compensation for heart damage and strokes they claim were caused by Vioxx, the Cox-2 inhibitor produced by Merck. The drug company anticipates legal action in Europe, Canada, Brazil, Australia and Israel.

Merck is hoarding $604m (?320m) to defend itself over several years, a cost which left the company’s fourth quarter profits down by 21 per cent. Merck has lost over $800m due to Vioxx since it was pulled from the shelves in September 2004.

A controversial study published in The Lancet by an employee of the US Food and Drug Administration (FDA), David Graham, found that as many as 140 000 cases of heart disease and up to 56 000 deaths in the US could have been caused by the painkiller over the five years it was on the market. The study, which ran over three years at Kaiser Permanente hospital in California, was sponsored by the FDA and scheduled for publication in November 2004. The risk of heart disease and death was substantially higher among patients taking Vioxx compared with ibuprofen, naproxen, and another Cox-2 inhibitor Pfizer’s Celebrex. Graham says the FDA delayed publication until January 2005.

Meanwhile, a flurry of papers on the safety of Cox-2 inhibitors has been published, including a University of Connecticut School of Medicine study led by William White. His team report in the Archives of Internal Medicine that Vioxx treatment increased blood pressure significantly in patients with type two diabetes, hypertension or osteoarthritis. This was not the case for Celebrex or naproxen in the same patient group. Elsewhere, the jury is still out on Celebrex. Researchers at the US National Institutes of Health found no increased cardiovascular risk for elderly patients, but a US National Cancer Institute trial on cancer patients measured a more than doubled risk of cardiovascular problems and suspended the drug. Also, an unpublished study, coauthored by Graham, links high doses of Celebrex to heart problems.

Despite this uncertainty, experts seem to agree on one thing: sales of the Cox-2 class of drugs will be slashed in the wake of the high-profile Vioxx trials.

Helen Carmichael