Reported Adverse Drug Reaction Cases
Fluoroquinolones and tendon disorders
The association between fluoroquinolone antibiotics and tendon disorders (especially involving the Achilles tendon) has been
reported by ADRAC and has recently been confirmed by an epidemiological study.1,2,3 A group of Dutch workers reviewed data
from a large UK general practice database. They studied a cohort of 46,776 patients who had used fluoroquinolones over a 6 year
period and identified 704 cases of Achilles tendinitis and 38 cases of Achilles tendon rupture. Current use of fluoroquinolones was
associated with 46 of these cases. The adjusted relative risk of Achilles tendon disorders with current use of fluoroquinolones was
1.9 (95% confidence interval 1.3 to 2.6). This risk was increased to 3.2 (2.1 to 4.9) among patients aged 60 and over and was not
significant in patients under 60 at 0.9 (0.5 to 1.6). In patients aged 60 or over, concurrent use of corticosteroids and luoroquinolones increased the relative risk to 6.2 (3.0 to 12.8).
There have been 112 Australian cases of tendon disorders with the fluoroquinolones reported to ADRAC, including 30 cases of tendon rupture. Almost all have involved the Achilles tendon. Most occurred with ciprofloxacin (100) but there have also been cases with norfloxacin (9), gatifloxacin, enoxacin and moxifloxacin (all 1 each). It is not known why there have been so many more reports with ciprofloxacin as it and norfloxacin have had a similar number of prescriptions (over 600,000) dispensed on the PBS over the past 5 years. The other three fluoroquinolones are not subsidised by the PBS. In the Dutch study, ciprofloxacin and norfloxacin had a similar risk but there was an increased risk with ofloxacin, which is not available in Australia. Of the 106 reports where the age was specified, 73 patients were aged 60 or over, and 20 other patients were in their fifties. Although concomitant medication was not always documented, 47 patients were taking oral corticosteroids. With the marketing of two new fluoroquinolones (gatifloxacin, moxifloxacin), ADRAC wishes to remind prescribers that tendon disorders are a class effect of fluoroquinolones and that increasing age and concomitant corticosteroids are established risk factors. Patients should be advised to be alert for pain or discomfort in the Achilles tendon or calf and inform their doctors if this occurs.