From the Guidelines
Amiodarone should be held if liver function tests exceed 3 times the upper limit of normal, as this indicates potential liver toxicity, which occurs at a rate of 0.6 percent annually 1. The parameters to hold amiodarone due to potential toxicity include:
- Liver function tests exceeding 3 times the upper limit of normal, as this is a common indicator of liver toxicity in patients receiving long-term amiodarone therapy 1
- Signs of toxicity such as QTc prolongation, PR interval prolongation, new heart block, bradycardia, or significant symptoms of toxicity
- Thyroid dysfunction, particularly thyrotoxicosis, as amiodarone can affect thyroid function 1
- Pulmonary toxicity, suspected by new infiltrates, dyspnea, cough, or decreased diffusion capacity, as amiodarone has been associated with lung toxicity 1
- Visual changes, neurological symptoms, or severe skin reactions, as these can be indicative of amiodarone toxicity 1 It is essential to regularly monitor ECG, liver function, thyroid function, and pulmonary status in patients on long-term amiodarone therapy to promptly identify potential toxicity and hold the medication if necessary 1. In acute situations where amiodarone toxicity is suspected, supportive care should be provided while the drug is cleared, which may require temporary pacing for severe bradycardia or heart block. The dosage of amiodarone should be kept at the lowest effective level, and potential drug interactions must be considered, especially with digoxin and warfarin 1.
From the FDA Drug Label
The dose regimen consisted of an initial rapid loading infusion, followed by a slower 6-hour loading infusion, and then an 18-hour maintenance infusion. The maintenance infusion was continued up to hour 48 Additional 10-minute infusions of 150 mg amiodarone HCl injection were given for “breakthrough” VT/VF Amiodarone HCl injection has been found to leach out plasticizers, including DEHP [di-(2-ethylhexyl)phthalate] from intravenous tubing (including PVC tubing)
The parameters to hold amiodarone due to potential toxicity include:
- Hypotension: Amiodarone can cause hypotension, and the risk is increased with higher doses.
- QTc prolongation: Amiodarone can cause QTc prolongation, which can increase the risk of torsades de pointes.
- Electrolyte disturbances: Hypokalemia or hypomagnesemia can exacerbate the risk of QTc prolongation and torsades de pointes.
- Liver enzyme elevations: Amiodarone can cause liver enzyme elevations, and the risk is increased with higher doses.
- Renal impairment: Although amiodarone is not significantly affected by renal impairment, close monitoring is recommended in patients with severe renal disease.
It is essential to monitor patients closely for these potential toxicities and adjust the dose or discontinue treatment as needed. 2, 2, 2
From the Research
Parameters to Hold Amiodarone
The following parameters indicate when to hold amiodarone due to potential toxicity:
- Significant conduction system disease 3
- Significant liver or pulmonary disease 3
- Hyperthyroidism 3
- New symptoms or adverse reactions in patients taking amiodarone 3
- Severe side effects, such as:
- Elevated liver enzymes (e.g., aspartate aminotransferase, alanine aminotransferase) 5
- Abnormal thyroid function tests (e.g., thyroid-stimulating hormone, free thyroxine) 5
- Pulmonary toxicity (e.g., interstitial pneumonitis) 6, 7, 5
- Hepatic toxicity (e.g., hepatitis) 6, 7, 5
Monitoring and Dose Adjustment
Regular monitoring of patients taking amiodarone is crucial to identify potential toxicity early on. This includes: