Australia’s healthcare regulator has pulled Novartis’ COX-2 inhibitor Prexige from the market after a number of cases of serious liver side effects were reported in patients taking the drug, which is used for the treatment of osteoarthritis and acute pain.

The Therapeutic Goods Administration has cancelled the registration of Prexige (lumiracoxib) after its principal medical adviser, Rohan Hammett, noted that the agency had received eight reports of serious liver adverse reactions to the drug, including two deaths and two liver transplants.

The TGA and the Adverse Drug Reactions Advisory Committee “have urgently investigated these reports” and pulled Prexige “due to the severity of the side effects associated with this drug," Dr Hammett said, adding that “it seems that the longer people are on the medicine, the greater the chance of liver injury”. Approximately 60,000 people take lumiracoxib in Australia, where it was first approved in July 2004 but it has only recently become widely used since being listed on the country’s Pharmaceutical Benefits Scheme in 2006.

Novartis agreed to withdraw all doses of Prexige, with immediate effect, but noted that most of the cases in Australia involved patients being prescribed 200mg doses of the drug and one was for 400mg. However, “the 100mg dose of Prexige, which is the recommended dose worldwide for treatment of osteoarthritis, has not been associated with an unexpected incidence of liver-related side effects,” the Basel-headquartered firm pointed out.

Despite the Australia withdrawal, it does not seem that Novartis is going to take Prexige off the market in the 50 or so other countries where it is available. Serious liver side effects have been reported rarely for all COX-2 inhibitors and traditional non-steroidal anti-inflammatory drugs, the company noted, and lumiracoxib’s label already carries a warning of liver toxicity.

Prexige 100mg tablets, given once daily, received full European marketing approval last December for symptomatic relief in the treatment of knee and hip osteoarthritis. Novartis may seek approval for the drug in the USA later this year and the firm will be hoping it can overcome the fact that COX-2 inhibitors are haunted by the spectre of Merck & Co’s Vioxx (rofecoxib) which was pulled from the market in 2004.

Patent extension for Diovan

Better news for Novartis came from the US Food and Drug Administration which has granted additional six months’ marketing exclusivity for the firm’s antihypertensive Diovan (valsartan) based on studies conducted in children with high blood pressure. Getting paediatric exclusivity on the drug extends its patent protection in the USA until September 2012 and Novartis noted that an FDA decision on a possible indication to treat children and adolescents is anticipated by the end of 2007.