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Azithromycin Safety Concerns Reach the FDA

Darrell Hulisz, RPh, PharmD
Jamie Eiben

May 25, 2012

A recent study published in the May 17th issue of the New England Journal of Medicine has sparked concern over the cardiovascular safety of azithromycin.1 The publication coincided with a press release issued by the FDA to address the issue.2 The study was an observational cohort analysis of mortality in Tennessee Medicaid patients who received a 5-day course of azithromycin (347,795 total prescriptions), as compared to those who received no antibiotic, amoxicillin, ciprofloxacin or levofloxacin. Specifically, the study tested the hypothesis that increased cardiovascular events could lead to sudden cardiac death in patients receiving azithromycin. This would theoretically be due to the drug's ability to adversely affect cardiac conduction by prolonging the QT interval. Prolonged QT interval predisposes patients to a sometimes fatal arrhythmia known as Torsades de Pontes (TdP), a type of polymorphic ventricular tachycardia that has long been associated with the macrolide, erythromycin. In this study, there was a small increase in the risk for sudden cardiac death, relative to the other comparison groups, but similar to that seen with levofloxacin. The risk was most pronounced among patients with a high baseline risk of cardiovascular disease.

Last year the FDA reviewed macrolide drug labeling information related to QT interval prolongation and TdP. Subsequently, the labeling for azithromycin extended release for oral suspension was revised in March 2012 to include new warnings regarding the risk for QT interval prolongation, which appears to be low. The drug labels for clarithromycin and erythromycin also contain information about QT interval prolongation. The FDA plans to update risk information in the labeling for additional antibiotics. Patients taking azithromycin should not stop taking the antibiotic without talking to their healthcare provider first. Pharmacists should be aware of the potential for QT interval prolongation and cardiac arrhythmias when dispensing azithromycin, especially in patients who are already receiving drugs known to prolong ventricular repolarization. Examples include amitriptyline, thioridazine, moxifloxacin, methadone, quinidine and other antiarrhythmia agents. Pharmacists should also be aware of conditions associated with TdP, such as hypokalemia and hypomagnesemia.

Ray WA, Murray KT, Hall K, Arbogast PG, Stein CM. Azithromycin and the risk of cardiovascular death. N Engl J Med 2012; 366:1881-1890.

FDA statement regarding azithromycin (Zithromax) and the risk of cardiovascular death. http://www.fda.gov/Drugs/DrugSafety/ucm304372.htm.

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