Citing an alarming rise in the number of personal injuries related to tendon ruptures in patients taking fluoroquinolone antibiotics like Cipro and Tequin, Public Citizen has petitioned the FDA to insert a black box warning on the entire class of antibiotics containing fluoroquinolones.

Fluoroquinolone antibiotics are prescribed for a wide range of infections, including respiratory, gastrointestinal, and genitor-urinary tract infections. In 1996, Public Citizen successfully petitioned the FDA to add a warning about the risk of tendon rupture and tendonitis to the package insert for these drugs. Although the exact way in which this class of drugs affects tendons is unknown, Public Citizen cites speculation that fluoroquinolones are "directly toxic to tendon fibers" that have a limited blood supply. Public Citizen found the that 89.8 percent of the tendon ruptures reported by patients on fluoroquinolone antibiotics involved the Achilles tendon, an area of the tendon with the poorest blood supply.

Because Achilles tendon rupture is typically related to sports injuries in younger men about 35 years of age, Public Citizen felt the demographics of Achilles tendon injuries related to fluoroquinolone antibiotic patients were especially relevant. Most Achilles tendon injuries linked to antibiotics were reported by women with a mean age of 59 years.

Antibiotics sold in this class include:

• Cipro (generic name: ciprofloxacin)
• Tequin (generic name: gatifloxacin)
• Levaquin (generic name: levofloxacin)
• Penetrex (generic name: enoxacin)
• Maxaquin (generic name: lomefloxacin)
• Avelox (generic name: moxifloxacin)
• Noroxin (generic name: norfloxacin)
• Floxin (generic name: ofloxacin)

Public Citizen searched the FDA Adverse Event reporting database for all reports related to fluoroquinolones and tendon disorders between November 1997 and December 31, 2006. The group found 262 reports of tendon ruptures in that time period, of which 175 had been reported since the beginning of 2003. Due to the serious rise in cases of tendon failure, Public Citizen feels that the non-bolded warning of possible tendon injury is inadequate to protect consumers and is demanding a black box warning. A black box is the most serious injury warning placed by the FDA on a package insert and is featured at the top of package information about a drug. Black boxes typically include warning signs of injuries and illnesses associates with drug risks.

"Tendon ruptures associated with these drugs continue to occur at a disturbing rate but could be prevented if doctors and patients were more aware of early warning signals, such as the onset of tendon pain, and switched to other antibiotics," said Sidney Wolfe, Public Citizen's director of Health Research. "The FDA must act."

Sources: Steve Mitchell, "Public Citizen urges antibiotic warnings," United Press International, August 29, 2006; "Sterner Injury Warnings Sought for Meds," Associated Press, August 29, 2006; "FDA Should Warn of Tendon Ruptures Linked to Cipro, Levaquin, Other Antibiotics in Same Class," Public Citizen, August 29, 2006; Sidney M. Wolfe, M.D., Health Research Group Publication #1781 (Public Citizen Petitions the FDA to Include a Black Box Warning on Fluoroquinolone Antibiotics), August 29, 2006.