The US Food and Drug Administration yesterday slapped new safety information onto the labeling for Sanofi-Aventis' ketolide antibiotic Ketek (telithromycin) after reports of liver problems were uncovered.

Indicated for use in patients with chronic bronchitis, acute bacterial sinusitis and community acquired pneumonia, recent reports have thrown up cases of serious liver injury and liver failure in patients taking Ketek. In total, there have been four reported deaths and one liver transplant after the administration of the drug.

However, the agency has voted to keep Ketek on the market - saying that its benefits outweigh the risks. “We are advising both patients taking Ketek and their doctors to be on the alert for signs and symptoms of liver problems," said Dr Steven Galson, Director for the FDA's Center for Drug Evaluation and Research. These include fatigue, malaise, loss of appetite, nausea, yellow skin and dark-colored urine.

Ketek was finally approved in the USA in 2004, after being turned down in both 2001 and 2003. At this point, the FDA says the risk of liver problems was equivalent to other antibiotics, a finding backed up in a safety evaluation conducted one year later. However, since becoming more widely used, the agency has received reports of serious liver problems, including acute liver failure leading to transplantation and death in a small number of cases. The European Medicines Agency has also tightened up labeling for the drug to warn of liver side effects.

The FDA has previously come under fire for its approval of Ketek, and its alleged failure to protect the US public from 'dangerous drugs' has been in the news again this week. In a statement posted on consumer lobby group Public Citizen's website, Representative Henry Waxman says: “FDA was our country's first consumer protection agency and Americans have relied on FDA to ensure the safety of their food and drugs for 100 years,” said. “Under the Bush Administration, FDA has undermined enforcement and betrayed its consumer-first legacy. FDA must start enforcing the law and return to a culture that places public health concerns ahead of industry profits.” Republican Senator Charles Grassley and Democrat Representatives Edward Markey and Henry Waxman have previously said there should be an investigation by Congress into the FDA's approval process for Ketek.

Sanofi-Aventis has not reported Ketek sales since the third quarter of 2005, when it posted a 7.3% decline in turnover to 38 million euros ($47m) year-on-year, and the antibiotic is a minor product for the company despite once-touted as a potential blockbuster.