Health Canada asks for tendon warning for some antibiotics

Health Canada announced Thursday that it will ask makers of a class of antibiotics to include a prominent warning on the label that the drugs can lead to tendon ruptures.

The announcement follows on the heels of a similar policy decision from the U.S. Food and Drug Administration. That agency revealed Tuesday that it was asking manufacturers of fluoroquinolone drugs to put a "black box" warning the FDA's most stringent safety labelling requirement on their products.

In an e-mailed response to questions posed Tuesday, Health Canada said it will ask manufacturers of fluoroquinolones to include a "box warning" on the product monographs alerting people who take the drugs of the fact they may be at higher risk of tendon ruptures.

Drugs in the fluoroquinolone class include ciprofloxacin (Cipro), levofloxacin, norfloxacin, ofloxacin, gemifloxacin and moxifloxacin.

The Health Canada response, e-mailed by spokesperson Alastair Sinclair, said that "tendonitis, tendon disorder and tendon rupture are known adverse reactions for quinolones."

It's not clear why the drugs would raise the risk of tendon injuries, an atypical adverse reaction to an antibiotic.

The U.S. drug regulator issued the demand for black box warnings under pressure from the consumer group Public Citizen, which unsuccessfully petitioned and then sued the FDA to require the warnings.

In issuing their call, FDA officials stress that many of the serious injuries appeared to be preventable if patients stopped taking the drugs at the first sign of pain or swelling in a tendon. Patients who do that should contact their doctor and arrange to switch to an alternative antibiotic, the agency said.

Tendons are cords of tissue that join muscles and bones, and are essential in movement. The most common kind of rupture reported to the FDA involved the Achilles tendon in the heel, but some also involved the rotator cuff in the shoulder, and tendons in the hands, biceps, and even the thumb.

An analysis of adverse events reported to the FDA found that patients with the highest risk of problems included people over 60, those with kidney, heart and lung transplants, and those also taking steroids.