Certain Antibiotics Linked to Tendon Ruptures

By Anastacia Mott Austin

While some patients taking Cipro and Levaquin reported feelings of tenderness and pain in tendons before they ruptured, others said they had no warning at all, just a "snap" sound, and then an excruciating Achilles tendon rupture.

While the two drugs already contained language warning of an increased susceptibility to tendon ruptures while taking them, the FDA’s "black box" warning, so called because of its bold type surrounded by a black outline, is the strongest warning that can be placed on a medication.

The drugs fall into a class of antibiotics called flouroquinolones, and experts are not sure why they increase the risk of tendon rupture. Some say that they may interfere with collagen production, thus weakening the tendons. The most common type of injury experienced was an Achilles tendon rupture, an extremely painful injury of the tendon connecting the back of the calf to the bottom of the foot.

Other tendon injuries occurred at the rotator cuff in the shoulder, hands, and even thumbs. In addition to the ruptures, hundreds of patients reported tendonitis, an inflamed, painful swelling of the tendons. Increased numbers of calls to the FDA of reports of tendon injuries prompted the investigation into the drugs and the new warning requirement.

The FDA will also require a medication guide to be given to patients along with their medication, explaining the possible side effects.

Cipro is the antibiotic of choice to treat anthrax, and it became a near-household name as people panicked and tried to stockpile the drug in case of biological warfare. Indeed, the U.S. does have a store of Cipro on hand in case of just such a scenario. But for everyday use, Cipro is often chosen to treat urinary tract infections, and Levaquin is most often used for respiratory infections.

Medical experts say that the ruptures with no warning are more rare, and that if patients are aware of the connection, they can stop taking the flouroquinolone drugs if they notice painful tendons and change to a different drug.

Patients most at risk include those older than 60, and those with certain organ transplants, like kidney, lung, or heart transplants. People taking steroids are also at an increased risk.