Clarithromycin-Related Toxic Effects of Digoxin

To the Editor: Digitalis glycosides and macrolide antibiotics are both commonly prescribed medications. Erythromycin prolongs the clearance of digoxin by altering the flora in the distal portion of the intestine that metabolizes digoxin to various inactive compounds that can be found in the stool and urine. When erythromycin is ingested by patients receiving oral or intravenous digoxin, the formation of these metabolites decreases and serum digoxin concentrations increase substantially. 1 Clarithromycin may have a similar effect on the metabolism of digoxin. We report the occurrence of elevated serum digoxin concentrations and toxic effects of digoxin during clarithromycin therapy in a patient . . .