Physicians may want to consider prescribing antibiotics other than azithromycin and levofloxacin to older patients, based on the findings of a study published in the March/April issue of Annals of Family Medicine. Researchers found that both antibiotics increase the risk of mortality and arrhythmia during different time frames.

Gowtham A. Rao, MD, PhD, MPH, of the University of South Carolina in Columbia, and colleagues used data from 14 million patients who visited 140 Veterans Affairs (VA) Medical Centers and 600 community-based clinics between 1999 and 2012 who received prescriptions for exclusively amoxicillin, azithromycin or levofloxacin. They compared the three drugs based on the outcomes of all-cause mortality and serious cardiac arrhythmia. Azithromycin was typically prescribed for five days and the other drugs for 10 days.

Compared with amoxicillin, patients who took azithromycin for the first five days had a significantly higher risk of death (hazard ratio [HR] 1.48) and serious arrhythmia (HR 1.77). On days six through 10, however, there was no statistically significant difference in risk.

The risk of death and the risk of serious arrhythmia for patients taking levofloxacin were also significantly higher compared with amoxicillin (HR 2.49 and 2.43), and this difference persisted through all 10 days of treatment (HR 1.95 and 1.75).

Their findings, the authors noted, support announcements by the FDA in 2011 and 2013 that warned about azithromycin’s association with a prolonged QT interval. They urged caution when prescribing these antibiotics to certain patients.

“There are usually multiple antibiotic choices available for older patients, especially those with cardiac comorbidities; physicians may consider prescribing medications other than azithromycin and levofloxacin,” they wrote.