BACKGROUND: Erythromycin has been associated with prolongation of myocardial repolarization and torsades de pointes (TdP). METHODS: To determine the frequency, dose-response, and risk factors for erythromycin-associated prolongation of myocardial repolarization, we observed data of patients admitted to our hospital with pneumonia who were treated with erythromycin. RESULTS: In 35 women and 28 men enrolled in this study, the QTc increased from 434 +/- 4 milliseconds at baseline to 464 +/- 5 milliseconds after receiving a cumulative dose of 3.2 +/- 0.2 g of erythromycin. Neither age, sex, presence of preexistent congestive heart failure/coronary artery disease, electrolyte values, nor cumulative dose of erythromycin was associated with QTc prolongation. In 27 patients who received intravenous erythromycin for 3 days, the QTc increased from 427 +/- 5 milliseconds before to 461 +/- 8 milliseconds at 24 hours but did not increase further by day 3 (457 +/- 10 milliseconds). No patient in this cohort had TdP. CONCLUSIONS: Erythromycin therapy is associated with prolongation of myocardial repolarization that manifests after the first few doses in a majority of patients.
BACKGROUND:Erythromycin has been associated with prolongation of myocardial repolarization and torsades de pointes (TdP). METHODS: To determine the frequency, dose-response, and risk factors for erythromycin-associated prolongation of myocardial repolarization, we observed data of patients admitted to our hospital with pneumonia who were treated with erythromycin. RESULTS: In 35 women and 28 men enrolled in this study, the QTc increased from 434 +/- 4 milliseconds at baseline to 464 +/- 5 milliseconds after receiving a cumulative dose of 3.2 +/- 0.2 g of erythromycin. Neither age, sex, presence of preexistent congestive heart failure/coronary artery disease, electrolyte values, nor cumulative dose of erythromycin was associated with QTc prolongation. In 27 patients who received intravenous erythromycin for 3 days, the QTc increased from 427 +/- 5 milliseconds before to 461 +/- 8 milliseconds at 24 hours but did not increase further by day 3 (457 +/- 10 milliseconds). No patient in this cohort had TdP. CONCLUSIONS:Erythromycin therapy is associated with prolongation of myocardial repolarization that manifests after the first few doses in a majority of patients.