Chronic Digoxin Toxicity Precipitated by Dronedarone.

To report the case of a patient who presented with chronic symptoms attributable to dronedarone-induced digoxin toxicity. A review of the literature is also provided.

This case report details a case of a 77-year-old male patient who presented to the hospital with multiple ambiguous symptoms that lasted several weeks. The patient was later hospitalized for symptoms of chronic digoxin toxicity, including prolonged nausea, diarrhea, weakness, and lack of appetite. The patient had a long history of digoxin use for control of his atrial fibrillation but experienced signs and symptoms of toxicity only after the addition of dronedarone.

Both the Naranjo and Drug Interaction Probability Scales indicated a "probable" relationship between the development of digoxin toxicity and dronedarone. Due to a p-glycoprotein-mediated interaction, dronedarone is able to decrease the renal clearance of digoxin, thus putting patients at risk for potentially fatal digoxin toxicity.

This is the second case report detailing dronedarone-induced digoxin toxicity and the first to focus on chronic digoxin toxicity. The presentation, possible causes, and drug-drug interactions associated with digoxin toxicity are described. This report aims to increase clinicians' awareness of this possible complication. It is recommended that digoxin be discontinued prior to initiating dronedarone. If concomitant therapy is absolutely necessary, the dose of digoxin should be halved prior to initiating dronedarone. Digoxin plasma levels should be monitored closely, with frequent patient evaluation for signs and symptoms of digoxin toxicity.