Use of clarithromycin could result in potentially avoidable deaths from heart complications, according to researchers, who found current use of the antibiotic was linked to a 76% increased risk of cardiac deaths compared with taking penicillin.
Women appeared to be particularly affected, with a more than two-fold risk increase, whereas the association was not significant in men when looked at separately, according to the Danish study published in the BMJ.
The authors caution against a change in prescribing policy, because the absolute risk is small, but claim that confirmation of the findings should be an ‘urgent priority’.
Macrolide antibiotics prolong the duration of the QT interval and have previously been thought to increase the risk of potentially fatal arrhythmias.
The Danish researchers sought to investigate the link between macrolide use and fatal arrhythmias, comparing use of the macrolides clarithromycin and roxithromycin against use of penicillin V – a non-macrolide antibiotic used for similar indications. The study included nearly two million adult patients aged between 40 and 75 with over five million courses of antibiotic treatment.
While roxithromycin was not linked to an increased risk of cardiac death compared with penicillin V, current clarithromycin use was associated with an excess of 37 deaths for every one million treatment courses.
The researchers advised their finding should have ‘limited effect on prescribing practice in individual patients’, although they add patients ‘with strong risk factors for drug-induced arrhythmia’ may be a ‘possible exception’.
They concluded: ‘Before these results are used to guide clinical decision making, confirmation in independent populations is an urgent priority, given the widespread use of macrolide antibiotics.’