Amiodarone Digoxin Interaction

A 67 year old male has a past medical history of hypertension, atrial fibrillation, CHF, and osteoarthritis.  He has had numerous issues with his cardiac status and it has led him to frequent physician visits, including involvement of a cardiologist.

This gentleman has been on digoxin 250 mcg daily with digoxin levels around the 0.8 mark.  He has had no symptoms of toxicity.  Due to the cardiologists findings, he feels it is appropriate to add amiodarone to this patient’s regimen.

There’s a couple of important points I want to address here regarding the digoxin.

  1. Clarification would be nice to identify what the digoxin is being used for.  Is it being used for heart failure, atrial fibrillation, or both?
  2. The digoxin level and no toxicity seems to be fine for this patient.  However, from my experience, I have a heightened awareness when I see patients on the 250 mcg daily dose.  I would keep an extra close eye on this dosing.
  3. Of course the amiodarone digoxin interaction is one you need to know! Amiodarone can significantly raise the concentration of digoxin in the body potentially leading to digoxin toxicity.  A reduction in the dose of digoxin will likely be required in this situation with a new start of amiodarone.  The cardiologist would hopefully be all over this drug interaction, but so should we as pharmacists!

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8 Comments

  1. Felipe Lopez

    Nicely done. I am currently on an anticoagulation rotation and learning a lot about CHF and Afib.

    Reply
    • Eric Christianson

      Thanks Felipe – good luck on the rotation!

      Reply
  2. Rajesh Thalapparambath

    If you are starting Amiodarone on a patient who is already stabilized on Digoxin, a 50% reduction in Digoxin dose is suggested.

    Reply
    • MITchel Phillips

      I was on digxon since 08and in April 18 Dr started. Me on amiodaron. In june of that year I ended up in sta Ford 12 days all most died. And I’ve had a icd how could my Dr make that mistake???

      Reply
  3. Craig Robertson

    Fabulous case. Reminds me of one of the first care of the elderly patients I had in my current post. Transferred from cardiology, developed confusion and consciousness level reduced. Digoxin level tested and high.

    Reply
    • Eric Christianson

      Thanks Craig!

      Reply
  4. Bill Jones

    I would need more information. Why start amiodarone? Was the patient having a lot of atrial fibrillation symptoms? Was the HR controlled with digoxin? The AFFIRM study results were no difference in rate and rhythm control strategies and changed the practice of trying to cardiovert patients. Did digoxin work (would not surprise me if it did not)? Again, why start amiodarone? I would be sure a TSH is checked or was done recently when starting amiodarone and recheck in 6-12 months. I would also want to know if amiodarone works to convert to NSR. If it does not work, then it should be stopped because of serious and possible life-threatening toxicity. Rate control with a beta-blocker, verapamil, or diltiazem can be used. If the HR was not controlled, I would also DC digoxin and find an alternative. I would lower the digoxin dose to 125 mcg daily in anticipation of the interaction and check a serum level in 4 weeks and 8 weeks. Studies done in the 1980s showed digoxin levels increasing for over 2 weeks and then the study was stopped when amiodarone was added to digoxin. The serum concentrations increased 2-3 fold in 2 studies (J Am Coll Cardiol 1984; 111; Chest 1984; 86: 75)

    Reply
  5. Gopinath

    May I know the demographic data of the patient along with co – morbid and other drugs, the patient using on for maintainance. Both the drugs are narrow index drugs and just reducing the dose of digoxin and the need of amiodarone is under ? If it is inevitable TDM + close monitoring are the choices …
    Good case study. Thank you and regards.

    Reply

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Written By Eric Christianson

November 6, 2016

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