Last Updated: 2008-01-04 13:17:49 -0400 (Reuters Health)

WASHINGTON (Reuters) – A consumer group asked a U.S. court on Thursday to force regulators to decide if stronger warnings should be added to certain antibiotics to alert doctors and patients about the risks of tendon rupture.

The antibiotics — fluoroquinolones widely prescribed for gastrointestinal, respiratory and urinary tract infections — include Johnson & Johnson’s Levaquin and Bayer AG’s Cipro and Avelox.

In August 2006, consumer group Public Citizen petitioned the Food and Drug Administration to add a "black box" warning, the strongest type available for prescription drugs, to fluoroquinolones about the risk of tendon injury and rupture.

The possibility of tendon rupture is now mentioned in the drug’s prescribing instructions, but the warning "is buried in a long list of possible adverse reactions and is far too easy to miss," said Dr. Sidney Wolfe, director of Public Citizen’s Health Research Group.

Stronger warnings could lead patients to switch to other antibiotics soon after tendon pain develops and before the tendon ruptures, the group argued in a complaint filed with the U.S. District Court for the District of Columbia.

Public Citizen also argued that the FDA was violating federal law by not ruling on the petition. The agency said in February 2007 it had not yet reached a decision because the petition raised complex issues requiring extensive review, according to Public Citizen.

"While the FDA sits idly by and ignores the problem, more people will suffer serious tendon ruptures that could have been prevented," Wolfe said.

The FDA has received 336 reports of tendon rupture in patients treated with fluoroquinolones from November 1997 through March 2007, Public Citizen said. The actual number is likely higher because only a fraction of potential side effects are typically reported to the agency.

FDA spokesman Christopher Kelly said the agency was evaluating the lawsuit but had no further comment.

A Johnson & Johnson spokeswoman had no immediate comment. A Bayer spokeswoman could not immediately be reached.