Labels on the generic antibiotics levofloxacin and ciprofloxacin should include warnings highlighted in boldface type and outlined in a black box describing the drugs' association with torn tendons and other disorders of the tissue that joins muscle to bone, the group, Public Citizen, said today in a petition to the U.S. Food and Drug Administration.

A warning already included in the instructions for use of the drugs, which Public Citizen requested and got in 1996, isn't strong enough, the group said in the petition. At least 175 patients using fluoroquinolones have reported ruptured tendons to the FDA since the beginning of 2003, said Public Citizen's Jay Parkinson and Sidney Wolfe, in the petition.

"A simple non-bolded warning buried in the list of possible adverse reactions to fluoroquinolones has been grossly inadequate," said Wolfe, director of Public Citizen's Health Research Group, and Parkinson, a research analyst, in the letter. "There is thus an urgent need for a black-box warning regarding the risk of tendonitis and tendon rupture."

Illinois Attorney General Lisa Madigan last year also asked the FDA to strengthen warnings about tendon damage on the drugs' labels. Madigan asked the FDA to educate doctors and patients about the risks of tendon tears and submit the entire fluoroquinolone drug class to the FDA's Drug Safety Oversight Board for review.

The FDA said in November that the request was still being analyzed, Madigan's office said in a letter released today.

An FDA database of adverse drug events shows there were 794 cases of tendon damage associated with fluoroquinolones from November 1997 through Dec. 31, 2005, Public Citizen said. Those injuries included 262 cases of tendon rupture, 258 cases of tendonitis, and 274 other reports of tendon disorders, the group said.

About 61 percent of the torn tendons in the FDA's database were associated with levofloxacin and 23 percent with ciprofloxacin, the petition said.