From the Guidelines
Amiodarone can cause several adverse effects, including thyroid dysfunction, pulmonary toxicity, liver enzyme abnormalities, and cardiac effects like bradycardia and heart block, and patients on this medication require regular monitoring of these potential side effects. The potential adverse effects of amiodarone are numerous and can be severe, affecting various organ systems. Common side effects include:
- Thyroid dysfunction (both hypothyroidism and hyperthyroidism)
- Pulmonary toxicity (including interstitial pneumonitis and fibrosis)
- Liver enzyme abnormalities
- Corneal microdeposits
- Photosensitivity
- Blue-gray skin discoloration with prolonged use
- Neurological effects like tremor, ataxia, and peripheral neuropathy
- Cardiac effects can include bradycardia, heart block, and rarely, torsades de pointes
- Gastrointestinal symptoms like nausea, vomiting, and constipation are common.
According to the most recent guidelines, such as the 2015 ESC Guidelines 1, regular monitoring of lung, liver, and thyroid function is necessary for patients on amiodarone. The longer the therapy and the higher the dose of amiodarone, the greater the likelihood that adverse side effects will require discontinuation of the drug. Lower maintenance doses (200mg daily or less) may reduce the risk of adverse effects while maintaining efficacy, as suggested by various studies, including those referenced in the 2015 ACC/AHA/HRS guideline 1. Patients should be advised to use sunscreen and protective clothing due to photosensitivity and to report any new respiratory symptoms, visual changes, or other concerning symptoms promptly.
From the FDA Drug Label
ADVERSE REACTIONS In a total of 1836 patients in controlled and uncontrolled clinical trials, 14% of patients received amiodarone HCl injection for at least one week, 5% received it for at least 2 weeks, 2% received it for at least 3 weeks, and 1% received it for more than 3 weeks, without an increased incidence of severe adverse reactions. The mean duration of therapy in these studies was 5. 6 days; median exposure was 3. 7 days. The most important treatment-emergent adverse effects were hypotension, asystole/cardiac arrest/ electromechanical dissociation (EMD), cardiogenic shock, congestive heart failure, bradycardia, liver function test abnormalities, VT, and AV block. The following table lists the most common (incidence ≥ 2%) treatment-emergent adverse events during amiodarone HCl injection therapy considered at least possibly drug-related. Other treatment-emergent possibly drug-related adverse events reported in less than 2% of patients receiving amiodarone HCl injection in controlled and uncontrolled studies included the following: abnormal kidney function, atrial fibrillation, diarrhea, increased ALT, increased AST, lung edema, nodal arrhythmia, prolonged QT interval, respiratory disorder, shock, sinus bradycardia, Stevens-Johnson syndrome, thrombocytopenia, VF, and vomiting (sometimes fatal)
The adverse effects of amiodarone include:
- Hypotension: the most common adverse effect
- Asystole/cardiac arrest/electromechanical dissociation (EMD)
- Cardiogenic shock
- Congestive heart failure
- Bradycardia
- Liver function test abnormalities
- VT
- AV block Other possible adverse effects reported in less than 2% of patients include:
- Abnormal kidney function
- Atrial fibrillation
- Diarrhea
- Increased ALT
- Increased AST
- Lung edema
- Nodal arrhythmia
- Prolonged QT interval
- Respiratory disorder
- Shock
- Sinus bradycardia
- Stevens-Johnson syndrome
- Thrombocytopenia
- VF
- Vomiting (sometimes fatal) 2 2
From the Research
Adverse Effects of Amiodarone
The adverse effect profile of amiodarone is diverse, involving several systems in the body. Some of the key adverse effects include:
- Cardiac effects: Amiodarone can cause cardiodepression, although this is not usually clinically significant in patients with left ventricular dysfunction 3.
- Thyroid effects: Amiodarone-induced thyrotoxicosis (AIT) and amiodarone-induced hypothyroidism (AIH) can occur, depending on the iodine status of individuals and prior thyroid disease 4, 5.
- Pulmonary effects: Interstitial pneumonitis is a potentially fatal adverse effect of amiodarone 3.
- Hepatic effects: Hepatitis is a potentially fatal adverse effect of amiodarone 3.
- Gastrointestinal effects: Amiodarone can cause gastrointestinal adverse effects, although these are often less serious 3.
- Ocular effects: Amiodarone can cause ocular adverse effects, although these are often less serious 3.
- Neurological effects: Amiodarone can cause neurological adverse effects, although these are often less serious 3.
- Dermatological effects: Amiodarone can cause dermatological adverse effects, although these are often less serious 3.
Management of Adverse Effects
To minimize the risk of adverse effects, pretreatment monitoring, regular assessments, and the use of minimum effective doses are necessary 3. Screening for thyroid disease before starting amiodarone and periodic monitoring of thyroid function tests are also advocated 4, 5. In cases of amiodarone-induced thyroid dysfunction, treatment may involve discontinuation of the drug, thioamides, corticosteroids, or other medications 4, 5.
Drug Interactions
Amiodarone interacts with several medications, including warfarin, simvastatin, and atorvastatin, and many HIV antiretroviral medications 6. Clinicians should be aware of these interactions to ensure safe and effective use of amiodarone.