Digoxin-itraconazole interaction: possible mechanisms.
OBJECTIVE
To document a case in which the administration of itraconazole was associated with an apparent decrease in digoxin clearance, resulting in an increase in the serum digoxin concentration.


METHODS
A man receiving digoxin for atrial fibrillation was concurrently treated with itraconazole 200 mg/d for esophageal candidiasis. The estimated urinary digoxin clearance was decreased during this combination therapy.


CONCLUSIONS
Digoxin is primarily cleared by the kidneys, and the mechanism of renal clearance involves both glomerular filtration and tubular secretion. We postulate that itraconazole or a metabolite of this compound may have resulted in decreased tubular secretion of digoxin, accounting for decreased urinary digoxin clearance.


CONCLUSIONS
Monitoring of serum digoxin concentrations should be performed if patients taking digoxin are treated with itraconazole. Further investigation is necessary to elucidate the nature of the interaction between digoxin and itraconazole.
Alderman
C P
CP
Repatriation General Hospital, Daw Park, South Australia.
Allcroft
P D
PD
D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000097:blood* / Q000627:therapeutic use / Q000652:urine; D000935:Antifungal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000150:complications / Q000188:drug therapy; D002177:Candidiasis / Q000150:complications / Q000188:drug therapy; D004077:Digoxin / Q000097:blood* / Q000627:therapeutic use / Q000652:urine; D004347:Drug Interactions; D004935:Esophageal Diseases / Q000150:complications / Q000188:drug therapy; D006801:Humans; D017964:Itraconazole / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male
D000889:Anti-Arrhythmia Agents; D000935:Antifungal Agents; D017964:Itraconazole; D004077:Digoxin