US regulators say that they wish to add black box warnings to the class of antibiotics that include Bayer’s Cipro and Johnson & Johnson’s Levaquin so that the labelling includes more information about the risk of tendonitis and tendon rupture.

The Food and Drug Administration has notified the manufacturers of fluoroquinolone antimicrobial drugs such as Cipro (ciprofloxacin) and Levaquin (levofloxacin) that although they currently carry information about the risk of tendon ruptures, a boxed warning is now going to be required. The agency added that the risks are greatest in people aged over 60, in kidney, heart and lung transplant recipients and when used in conjunction with steroids.

The FDA went on to say that fluoroquinolones should only be used for the treatment or prevention of infections that are proven or strongly suspected to be caused by bacteria. It is also notifying drugmakers of the need to develop and distribute a medication guide to alert patients about the possible side effects.

Public Citizen wants more
The move comes six months after influential consumer body Public Citizen sued the agency to require the black box warnings but the group believes the FDA should do more. Sidney Wolfe, director of the Health Research Group at Public Citizen, said that the latest announcement accomplishes two of the three steps it has urged the agency to take for nearly two years but “the FDA is silent on our request that it also send a warning letter to physicians clearly describing possible adverse reactions”.

He added that “we are troubled that the FDA is not doing everything within its power to prevent more people from needlessly suffering disabling tendon ruptures. Nothing could be simpler and more effective than a letter to doctors in addition to what the FDA has proposed”.

Public Citizen noted that from November 1997 through December 2007, there have been 407 reported cases of tendon rupture and 341 cases of tendinitis in patients using fluoroquinolone antibiotics. “Because only a small fraction of cases are typically reported to the FDA, the actual number of ruptures and other tendon injuries…is much higher”, it added.

Dr Wolfe added that “no one in the medical community disputes that these antibiotics can cause tendon ruptures, and the FDA has not learned anything new since we filed our petition and lawsuit. It shouldn’t require legal action to get the FDA to do its job”. He concluded by saying that “our lawsuit will continue until the FDA determines whether it will require companies to send a warning letter to doctors”.