Serious warning placed on antibiotic Ketek

The Food and Drug Administration (FDA) in the United States has issued a warning about an antibiotic used to treat sinusitis and bronchitis.

The FDA say the controversial drug Ketek was too risky to treat those diseases and although it will remain on the market to treat pneumonia, stronger warnings about possible side effects such as blurred vision and loss of consciousness, will be placed on the drug's labels.

The FDA also says the drug in future will carry a "black box" warning, the strongest possible, against its use by patients with a disease known as myasthenia gravis that causes muscle weakness.

The latest warnings follow a year-long FDA investigation into reports of severe liver damage and death in some Ketek patients that sparked debate over the drug's safety and also over the agency's handling of its approval.

Ketek, known generically as telithromycin, already carried a bold warning for possible liver damage and has been linked to 14 cases of severe liver problems, including five deaths.

The FDA announcement pre-empts a House Energy and Commerce subcommittee hearing on drug safety issues, including Ketek.

The subcommittee will examine irregularities in the approval of Ketek and the FDA's handling of the antibiotic also remains under investigation by the Senate.

Ketek, known generically as telithromycin, already carried a bold warning for possible liver damage.

The FDA has repeatedly been criticized by some for withholding information about Ketek's approval.

The agency cleared the drug in 2004 even though an investigation found a key safety study was tainted by fraud.

FDA officials said other data provided adequate reassurance.

Until late last year, doctors had prescribed the antibiotic more than 5.6 million times in the United States since it won FDA approval.

Ketek is produced by Paris-based drug company Sanofi Aventis.