Wednesday, July 16, 2008

Some Antibiotics Could Damage Tendons, FDA Says

(for original article and comments, see
As of this reprint, the statistics are under second review.)

Some antibiotic drugs such as Bayer AG's Cipro and Avelox as well as Merck & Co. Inc's Noroxin will be required to have a stronger "black box" warning about the risk of tendonitis and ruptured tendons, according to new Food and Drug Administration regulations issued Tuesday.

In addition, an FDA-approved medication guide must be provided to individuals upon the filling of their prescriptions. Other drugs affected by the new requirements include Oscient Pharmaceuticals Corp.'s Factive, Depomed Inc.'s Proquin XR, and Ortho-McNeil's (a Johnson & Johnson subsidiary) Levaquin and Floxin.

Cipro and Levaquin, two leading drugs included in the warning, have other uses as well. Cipro is commonly used to treat urinary tract infections and is also effective against deadly bacteria, anthrax, being one of the drugs stockpiled by the government should a bio-attack occur. Levaquin is used to treat respiratory infections.

When sold by generic manufacturers, Cipro is referred to as ciprofloxacin and Floxin as ofloxacin. All of the drugs affected fall under a drug class known as fluoroquinolones.

Tendons are the tough, fibrous connective tissue joining muscles and bones. Also called sinew, they are essential to body movement and receive a lot of tension. Overuse can lead to inflammation and tendonitis, and excess pressure, some diseases and steroids can lead to snaps or ruptures. Such issues are normally thought of as sports injuries in young men or men in their mid-30s.

FDA studies indicate that the risk of tendon ruptures is estimated at about three to four times higher than normal rate (about one in 100,000) for those taking fluoroquinolones, notes Dr. Renata Albrecht, head of the FDA's division focusing on infectious microbes and transplant issues. Also, the risk is greater in patients ages 60 and older, particularly those who have had certain organ transplants or are using steroid therapy.

With this in mind, doctors are advised to restrict use of the drugs to confirmed bacterial conditions, and patients with tendon pain should immediately stop taking the drug, halt all exercise and call their doctor.
Patients who do experience a rupture may recover without surgery, but if surgery is needed to repair a torn tendon, full recovery may not be possible.

The regulation comes in the wake of a January 2008 lawsuit by consumer group Public Citizen, which had petitioned for the "black box" warnings two years ago and is still pushing for a warning letter to be sent to physicians describing the possible adverse reactions, such as tendon pain, that could be caused by the drugs.

"If the doctor is left out of the loop, it just doesn't make any sense," Sidney Wolfe, head of Public Citizen's Health Research Group said to Reuters UK.

Current labels for all the drugs involved already contain cautions about tendon problems, but Edward Cox, director of the FDA's antimicrobial products office, said, "The FDA believes that these labeling changes will better inform health care providers and patients about the risk."

Also, since the presence of several hundred "continued reports" of tendon-related problems indicated that these warnings were not reaching some doctors and patients, "additional steps are warranted to better manage the risk of tendon rupture," said Dr. Albrecht.

The specific number of reported cases were not available from the FDA, but Public Citizen's Mr. Wolfe lists government data as noting the numbers as 407 ruptures and 341 tendonitis cases through 2007 and 262 tendon ruptures, 258 tendonitis and 274 other tendon disorders through 2005.

Ortho-McNeil and their parent company Johnson & Johnson will add the new warning to both Levaquin and Floxin, as will Merck & Co. for its drug Noroxin, according to spokeswomen for the two companies.
Oscient released a statement saying it would review the issue and the remaining companies were not available for comment.

Heather J. Chin can be reached at

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