The Fluoroquinolone Toxicity Research Foundation

 
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Tendon Damage Research                  See downloads for: Adobe Files



THE ACHILLES HEEL OF FLUOROQUINOLONES

One of the more unusual adverse reactions known to be associated with the fluoroquinolone antibiotics is the occurrence of tendinitis. This is a serious effect since it may progress to tendon rupture with many weeks of disability as a result. Over 200 cases have been reported in the literature with the majority from France. Most members of the class including ciprofloxacin, enoxacin, ofloxacin, and norfloxacin have been implicated. The Achilles tendon is most often involved.

In Australia, there have been 25 reports of tendinitis in association with fluoroquinolones. Most (22) have been with ciprofloxacin and the other three with norfloxacin. The majority of the patients involved were elderly, ranging in age from 46 to 91 (median 69) years and the sex distribution was equal. For ciprofloxacin, daily dosages ranged from 750 mg to 2250 mg although most (13) patients were taking 1000 mg daily. For norfloxacin, all three patients were taking the usual dose of 800 mg daily. Time to onset ranged from the same day that the drug was commenced (in two patients) to two months although in 13 of the 24 reports which provided the information, the reaction occurred within the first week. Almost all (23) of the reports specified the Achilles tendon as the site of the tendinitis. Tendinitis was described as bilateral in 11 cases. Only 8 patients had recovered at the time the report was submitted and the other patients were being treated with rest and/or physiotherapy. There have been no reports of tendon rupture in Australia although in one severe case, the patient required a plaster cast up to the mid thigh.

A number of risk factors have been identified with regard to this adverse reaction. These include old age, renal dysfunction, and concomitant corticosteroid therapy. Of the patients reported to ADRAC, 72% were older than 60 years. Nine of these patients were taking corticosteroids as were three of the younger patients.

Prescribers are reminded that tendinitis, especially involving the Achilles tendon, is a rare adverse effect of the fluoroquinolones. It is more likely to occur in association with the risk factors referred to above. The antibiotic should be withdrawn immediately to reduce the risk of tendon rupture.