Pay attention when patients are on amiodarone

Ensure that atrial fibrillation patients who start amiodarone (Cordarone) at 400 to 800 mg/day drop down to 100 to 200 mg/day after about a month.....
Abdelwahab Ward, BS Pharm, PharmD

Amiodarone (Cordarone, Cardiomep) has hundreds of interactions and a plethora of side effects, but it's still the most commonly prescribed antiarrhythmic. Renew your efforts to ensure safe use of amiodarone...

Firstly WATCH DOSING

Ensure that atrial fibrillation patients who start amiodarone (Cordarone) at 400 to 800 mg/day drop down to 100 to 200 mg/day after about a month. This is usually enough to control symptoms and minimize side effects.

Review all interaction alerts closely. These are usually serious. You can simply use Medscape drug interactions checker. For example, advise reducing warfarin doses by at least 20% when starting amiodarone (Cordarone) and expect it to take 6 to 8 weeks to stabilize INR.

  • Don't jump to a direct oral anticoagulant (Eliquis, etc) instead. These may also interact, but their effects can't be monitored with INR.
  • Also recommend decreasing oral digoxin doses by 50% when starting amiodarone and avoiding amiodarone with many hepatitis C drugs (Sovaldi, Harvoni, etc). If a statin is needed with amiodarone, suggest pravastatin or rosuvastatin (Crestor), these don't need dose adjustments like most other statins.
  • Be cautious with antibiotics such as macrolides or quinolones due to QT prolongation risk. For example, recommend doxycycline instead of azithromycin (Zithromax) if needed for COPD exacerbations.
  • Advise avoiding grapefruit juice because of potential toxicity.

EDUCATE about adverse reactions

Explain that about half of all amiodarone patients have side effects such as fatigue, tremor, or nausea. But tell patients to report dizziness, palpitations, or breathing problems. And emphasize the importance of sticking to routine follow-up and monitoring: liver function tests, thyroid, cardiovascular, lung function, and eye exams. For instance, advise checking TSH every 3 to 6 months to screen for hypo- or hyperthyroidism, either can occur in patients taking amiodarone. The effect of amiodarone on thyroid function does not depend on the dose and can occur at any time after initiating treatment. Further more, because of the high lipid solubility and long half-life of amiodarone, this effect can persist up to 1 year after discontinuing therapy.RECOMMEND SUNSCREEN to limit photosensitivity and possibly the blue-gray discoloration that can rarely occur with amiodarone. Expect interactions and side effects to last at least a few weeks after stopping amiodarone, since its half-life is about 60 days.

References

Abdelwahab Ward, BS Pharm, PharmD