When a patient is started on amiodarone, what adjustment should be made to their digoxin therapy?

When a patient begins therapy with amiodarone, it is essential to adjust their digoxin therapy due to the pharmacokinetic interactions between these two medications. Amiodarone can significantly increase the serum concentration of digoxin, primarily because it can inhibit the P-glycoprotein transporter in the intestines and the kidneys. This inhibition reduces the clearance of digoxin, which can lead to increased plasma levels and a higher risk of digoxin toxicity.

To mitigate the risk of toxicity, it is prudent to decrease the dose of digoxin. A common practice is to reduce the digoxin dose to a lower frequency and amount, such as 125 mcg three times weekly, which allows for continued therapeutic benefit while minimizing the potential adverse effects associated with elevated digoxin levels.

This adjustment ensures that the patient remains within a safe and effective range of digoxin without incurring the risks associated with increased drug concentrations due to the interaction with amiodarone. This proactive approach in adjusting digoxin therapy is crucial for patient safety and effective management of their cardiovascular condition.