Australian families whose relatives died or became seriously ill with liver damage after taking the Novartis Cox-2 painkiller have launched a class action lawsuit against the country’s drug regulator and the drugmaker, claiming they were “treated like guinea pigs.”

Peter Archer, whose wife Elaine died in late February, tells The Sydney Morning Herald he wanted to know why the Therapeutic Goods Administration approved the drug at double the dose of what was allowed in countries such as Canada and the UK for the treatment of osteoarthritis. And he accuses Novartis of holding “some sort of secret trial”.

His wife died from inoperable liver failure after taking 200 milligrams of Prexige a day for four months while she waited to see a rheumatologist. The TGA recalled Prexige last month after receiving eight reports of liver damage, including two deaths and two patients who required liver transplants. About 60,000 Australians have taken Prexige, predominantly for arthritis, since it was registered in November 2005, and most were on the 200-milligram dose.

The events led Novartis ceo Dan Vasella last week to acknowledge it is unlikely Prexige will gain FDA approval in the US.

Simon Harrison, a lawyer for the Archer family, says they want to know why the administration licensed the drug at the dosages of 200 milligrams and 400 milligrams rather than 100 milligrams, claiming international studies had revealed side effects such as liver damage.

“We want to know what inquiries were made by the TGA before this drug was licensed, what documentation they reviewed from overseas,” Mr Harrison says. “One of our clients commented that they’ve been treated like guinea pigs. I entirely agree.”

Mr Archer said his wife’s doc gave her three months’ worth of free samples, which included a daily dose of 200 milligrams for arthritic pain. “I think it’s disgusting. I have heard from other people all over the state who have said that their doctors were throwing it around like lollies.”

A TGA spokesman said there was no research indicating that a 100-milligram dose was safer than the higher doses. However, in June the administration insisted on a recommended dose of 100 milligrams for osteoarthritis.

“At the time the TGA approved the 200- and 400-milligram doses of Prexige there was no 100-milligram dose available,” the spokesman says. “There remains, today, no international research showing that 200-milligram and 400-milligram doses are more likely to cause liver failure than the 100-milligram dose.”

A Novartis spokeswoman tells the paper that the drugmaker is unaware of any legal action and denied knowingly put patients at risk.