From the FDA Drug Label
Amiodarone should be used with caution in patients receiving ß- receptor blocking agents (e.g., propranolol, a CYP3A4 inhibitor) or calcium channel antagonists (e.g., verapamil, a CYP3A4 substrate, and diltiazem, a CYP3A4 inhibitor) because of the possible potentiation of bradycardia, sinus arrest, and AV block; if necessary, amiodarone can continue to be used after insertion of a pacemaker in patients with severe bradycardia or sinus arrest Potentiation of warfarin-type (CYP2C9 and CYP3A4 substrate) anticoagulant response is almost always seen in patients receiving amiodarone and can result in serious or fatal bleeding The dose of the anticoagulant should be reduced by one-third to one-half, and prothrombin times should be monitored closely. In general, any added antiarrhythmic drug should be initiated at a lower than usual dose with careful monitoring. The continued need for the other antiarrhythmic agent should be reviewed after the effects of amiodarone have been established, and discontinuation ordinarily should be attempted. If the treatment is continued, these patients should be particularly carefully monitored for adverse effects, especially conduction disturbances and exacerbation of tachyarrhythmias, as amiodarone is continued In amiodarone-treated patients who require additional antiarrhythmic therapy, the initial dose of such agents should be approximately half of the usual recommended dose.
When to hold Amiodarone:
- Severe bradycardia or sinus arrest: Amiodarone may need to be held or a pacemaker inserted.
- Concomitant use with certain medications: such as warfarin, ß-blockers, or calcium channel antagonists, which may require dose adjustments or close monitoring.
- Serious or fatal bleeding: due to potentiation of anticoagulant response.
- Conduction disturbances or exacerbation of tachyarrhythmias: when used with other antiarrhythmic agents.
- QTc prolongation or TdP: when used with fluoroquinolones, macrolide antibiotics, or azoles. 1
From the Research
When to Hold Amiodarone
Amiodarone is a powerful antiarrhythmic medication used to treat various cardiac arrhythmias. However, its use is accompanied by potential risks and side effects. The decision to hold amiodarone should be based on careful consideration of the following factors:
- Toxicity and side effects: Amiodarone can cause thyroid, liver, and pulmonary toxicity, among other side effects. If a patient exhibits signs of toxicity, the medication should be held or discontinued 2, 3.
- Drug interactions: Amiodarone interacts with various medications, including warfarin, digoxin, and other antiarrhythmic agents. If a patient is taking any of these medications, the dose of amiodarone may need to be adjusted or the medication held 3, 4.
- Pregnancy and breastfeeding: Amiodarone is contraindicated in pregnant and breastfeeding women due to its potential to cause harm to the fetus or baby 3.
- Cardiac conditions: Amiodarone can be used to treat various cardiac conditions, including atrial fibrillation, ventricular tachycardia, and congestive heart failure. However, its use should be carefully monitored in patients with these conditions, and the medication should be held if the patient's condition worsens 2, 5.
- Electrophysiologic studies: Amiodarone can affect the results of electrophysiologic studies, and its use should be held before these studies are conducted 5.
Specific Situations to Hold Amiodarone
The following situations may require holding amiodarone:
- QT and QTc-interval prolongation: Amiodarone can cause QT and QTc-interval prolongation, which can increase the risk of ventricular arrhythmias. If a patient exhibits significant QT or QTc-interval prolongation, the medication should be held 2.
- Ventricular proarrhythmia: Amiodarone can rarely cause ventricular proarrhythmia, which can be life-threatening. If a patient exhibits signs of ventricular proarrhythmia, the medication should be held immediately 2.
- Thyroid dysfunction: Amiodarone can cause thyroid dysfunction, including hypothyroidism and hyperthyroidism. If a patient exhibits signs of thyroid dysfunction, the medication should be held or discontinued 2, 3.