Dangerous Drug Interaction: Digoxin-Amiodarone

Impact: Potential for digoxin toxicity.¹

Mechanism of Interaction: Multiple theories exist, but actual mechanism is unknown. Amiodarone may decrease the clearance of digoxin, resulting in prolonged digoxin activity. There may also be an additive effect on the sinus node of the heart.

Alternatives to Patient Management: Obtain digoxin level prior to initiation of amiodarone therapy. Then, decrease dose of digoxin by 25-50% and monitor digoxin levels once weekly for several weeks.^8,9 Digoxin therapy should be cautiously started in with hypokalemia, hypomagnesemia or hypothyroidism due to the potential for adverse drug reactions at lower digoxin levels.^10,11

Monitoring/Precautions:

1. Maintain digoxin level below 2ng/mL (2.6nmol/L).¹²
2. Monitor for signs and symptoms of digoxin toxicity (abdominal pain, anorexia, bizarre mental symptoms in the elderly, blurred vision, bradycardia, confusion, delirium, depression, diarrhea, disorientation, drowsiness, fatigue, hallucinations, halos around lights, visual acuity, mydriasis nausea, neuralgia, nightmares, personality changes, photophobia, restlessness, vertigo, vomiting, and weakness).
3. Monitor heart rate for bradycardia and EKG-look for elongated PR interval.
4. Monitor calcium, magnesium and potassium levels.

References: Follow this link for a complete list of references.

The above information serves only as a guide for use by qualified medical practitioners in understanding, handling and avoiding frequent and potentially dangerous drug interactions that occur in long-term care. This presentation is not intended to instruct a practitioner how to treat any medical condition, nor is it intended to replace a practitioner's best clinical judgment. AMDA expressly disclaims responsibility and liability for any adverse effects, damages or other consequences resulting from the use of any of the information contained in this presentation.