Erythromycin Plus Antihypertensives Increase Risk of Sudden...

"Oral erythromycin alone doubles the risk of sudden cardiac death, but when combined with the antihypertensives diltiazem or verapamil, the risk rises fivefold, according to the results of a study published in the Sept. 9 issue of the New England Journal of Medicine. 'Oral erythromycin prolongs cardiac repolarization and is associated with case reports of torsades de pointes,' write Wayne A. Ray, PhD, from Vanderbilt University School of Medicine in Nashville, Tennessee, and colleagues. 'Because erythromycin is extensively metabolized by cytochrome P-450 3A (CYP3A) isozymes, commonly used medications that inhibit the effects of CYP3A may increase plasma erythromycin concentrations, thereby increasing the risk of ventricular arrhythmias and sudden death.'"