FDA Revises Label Warnings On The Antibiotic Ketek

The US Food and Drug Administration (FDA) has revised the label warnings on the antibiotic Ketek, to improve safe use by patients. Ketek is the brand name of Telithromycin and is manufactured by Sanofi-Aventis.

The FDA has removed approval of the drug for treatment of acute bacterial infections associated with sinusitis and chronic bronchitis. Ketek retains FDA approval for treatment of community acquired pneumonia of "mild to moderate severity" but it will carry a black box label, the most severe level of warning issued by the FDA.

The new label will warn that patients with the muscle weakness autoimmune disease myasthenia gravis should not take the drug. It will also carry a stronger warning about potential side effects such as "visual disturbances" and "loss of consciousness".

This is the second time that Ketek's label has changed in the last 12 months. In June last year the label was strengthened to point out the danger of hepatic toxicity ( a rare but severe symptom of liver disease).

Dr Steven Galson, Director at the Center for Drug Evaluation and Research said the "Action is the result of comprehensive scientific analysis and thoughtful public discussion of the data available for Ketek, and includes important changes in the labeling designed to improve the safe use of Ketek by patients and give healthcare providers the most up-to-date prescribing information."

A new patient information leaflet will also accompany the prescription, explaining the drug's safe use and risks.

These changes reflect the advice given out in December last year by the FDA's Anti-Infective Drugs and Drug Safety and Risk Management Advisory Committees.

The committees pointed out that since the drug was approved in April 2004, new evidence shows that the balance of risks versus benefits has changed. Much of this relates to cases of liver damage, disturbed vision and loss of consciousness.

Dr John Jenkins, Director at the FDA's Center for Drug Evaluation and Research, Office of New Drugs, said that the new benefits versus risk assessment does not support the use of Ketek for self-limited and less serious illnesses such as sinusitis and bronchitis.

But he said the drug will continue to be "approved for community-acquired pneumonia of mild to moderate severity, which is a more serious illness that generally does not resolve without antibiotic therapy."

According to reports by the Associated Press the FDA's handling of Ketek is under Senate investigation. Also, today is the day that the House of Representatives Subcommittee on Oversight and Investigations is hearing witness statements on "The Adequacy of FDA Efforts to Assure the Safety of the Drug Supply", which according to a Bloomberg press report yesterday includes "irregularities in the approval of Ketek".

The drug has a somewhat tortuous pharmacological history. A group of antiobiotics called macrolides was developed to treat people allergic to penicillin. But then some bacteria became macrolide resistant. Enter the Ketolides - developed to defeat the macrolide-resistant bacteria that cause respiratory infections.

Telithromycin (the generic name for Ketek) is a ketolide antibiotic with a similar structure to one of the macrolides - Erythromycin. It works by stopping the bacteria from being able to produce protein which limits the spread of the colony in the respiratory tract.

Telithromycin is metabolized mostly in the liver and has a half life in the body of about 10 hours.

Click here for more information on Telithromycin from the FDA.

Click here for more information on Telithromycin from wikipedia.

Written by: Catharine Paddock
Writer: Medical News Today