Tuesday Aug 19, 2014 (foodconsumer.org) -- A new study published in thebmj.com suggests taking antibiotic clarithromycin to treat common bacterial infections may increase the risk of cardiac death.

Clarithromycin is one of macrolides - a class of antibiotics known to prolong the duration of electrical activity of the heart muscle or the QT interval and therefore increase the risk of potential fatal heart rhythm problems.

The current study was to test clarithromycin and another macrolide called roxithromycin to see how they affect the risk of cardiac death, compared to penicillin V, which has no known effect on the cardiac risk.

The study was based on data from 160,297 patients with clarithromycin, 588,988 with roxithromycin and 4,355,309 with penicillin V who received antibiotic treatment from 1997 through 2011.  The ages ranged from 40 to 74 years.  At the time of enrollment, patients with serious diseases were excluded from the analysis.

Ongoing use of clarithromycin was found correlated with 76% increased risk of cardiac death, compared with use of penicillin V.  When the antibiotic use was discontinued, then the patients were not at an elevated risk.

One million courses with clarithromycin were associated with 37 cardiac deaths.

Ongoing or past use of roxithromycin was not correlated with increased risk of cardiac death.

Because many patients are using clarithromycin, the findings should be confirmed as soon as possible so that prescription guidelines may be adjusted accordingly to reduce the risk of cardiac death. (David Liu, PHD)