Erythromycin and Sudden Death

Certain drugs such as erythromycin prolong the QT interval and increase risk for ventricular arrhythmias. Erythromycin is metabolized by the cytochrome P₄₅₀ isoenzyme CYP3A; drugs that inhibit CYP3A (e.g., some calcium-channel blockers, azole antifungals, protease inhibitors) raise blood levels of erythromycin and presumably potentiate its toxicity.

In this study of data from 1988 through 1993 -- drawn from the Tennessee Medicaid database -- researchers examined whether erythromycin was associated with risk for sudden cardiac death. Multivariable analysis revealed a twofold higher rate of sudden cardiac death among current erythromycin users than among nonusers. In contrast, current amoxicillin users and former erythromycin users exhibited n…