Cardiovascular risks with azithromycin and other antibacterial drugs.

n engl j med 368;18 nejm.org may 2, 2013 1665 During that year, we at the Food and Drug Administration (FDA) reviewed the labels of azithromycin and other approved macrolide antibacterials in view of cardiovascular risks that had become evident from published studies and reports emerging through postmarketing surveillance. On the basis of its review, the FDA approved revisions to azithromycin product labels regarding risks of QT-interval prolongation and the associated ventricular arrhythmia torsades de pointes. The revised labels advise against using azithromycin in patients with known risk factors such as QT-interval prolongation, hypokalemia, hypomagnesemia, bradycardia, or use of certain antiarrhythmic agents, including class IA (e.g., quinidine and procainamide) and class III (e.g., dofetilide, amiodarone, and sotalol) — drugs that can prolong the QT interval. In March 2013, the FDA announced that azithromycin labels had been further revised to reflect the results of a clinical study showing that azithromycin can prolong the corrected QT interval. In a 2012 observational study involving Tennessee Medicaid patients, Ray et al.1 quantified the risk of death from cardiovascular causes associated with azithromycin as compared with other antibacterial drugs or nonuse. The study showed that the risks of death, both from any cause and from cardiovascular causes, associated with azithromycin were greater than those associated with amoxicillin. For every 21,000 outpatient prescriptions written for azithromycin, one cardiovascular death occurred in excess of those observed with the same number of amoxicillin prescriptions. The excess risk over amoxicillin varied considerably according to cardiovascular risk factors; the researchers estimated that there was one excess cardiovascular death per 4100 prescriptions among patients at high cardiovascular risk but less than one per 100,000 among patients with lower cardiovascular risk. Cardiovascular Risks with Azithromycin and Other Antibacterial Drugs