Amiodarone

Oral
Intravenous
Class
Antiarrhythmics
Subclass
Class III antiarrhythmics
Substance name
Amiodarone hydrochloride
Brand names
Pacerone®
Common formulations
Tablet
Dosage and administration
Adults patients
Treatment
VF • Life-threatening, recurrent, refractory
•
Loading: 800-1,600 mg PO daily for 1-3 weeks until initial therapeutic response
•
Subsequently: 600-800 mg PO daily for 1 month
•
Maintenance: 400 mg PO daily
Taken consistently with regard to meals. Administer daily doses greater than 1,000 mg in divided doses.
VT • Life-threatening, recurrent, refractory, hemodynamically unstable
•
Loading: 800-1,600 mg PO daily for 1-3 weeks until initial therapeutic response
•
Subsequently: 600-800 mg PO daily for 1 month
•
Maintenance: 400 mg PO daily
Taken consistently with regard to meals. Administer daily doses greater than 1,000 mg in divided doses.
AF • Rate control • Off-label
•
Start at: 200 mg PO TID for 4 weeks
•
Maintenance: up to 200 mg PO daily
Fetal tachycardia • Off-label
•
Loading: 450-600 mg IV q6h for 2 days
•
Maintenance: 200-600 mg IV q24h until rhythm is restored or hydrops has resolved
Reduce loading dose to 200-300 mg orally q6h if previous drug therapy.
SVT • Ongoing management • Off-label
•
Start at: 400-600 mg PO daily, in divided doses, for 2-4 weeks
•
Maintenance: 100-200 mg PO daily
Consider administering up to 1,200 mg loading dose in an inpatient monitoring setting.
Prevention
Prevention of AF, during cardiac surgery • Off-label
•
Start at: 200 mg PO TID for 7 days before surgery
•
Maintenance: 200 mg PO daily until discharge
Alternative
•
10 mg/kg PO daily, in 2 divided doses, 6 days before through 6 days after surgery
Secondary prevention
Ventricular arrhythmias in patients with ischemic heart disease • Recurrent, significant symptoms or ICD shocks • Off-label
•
Start at: 400 mg PO BID-TID for 1-2 weeks
•
Maintenance: 300-400 mg PO daily
Reduce maintenance dose to 200 mg orally daily if possible.
Ventricular arrhythmias in patients with nonischemic cardiomyopathy • Recurrent, significant symptoms or ICD shocks • Off-label
•
Start at: 400 mg PO BID-TID for 1-2 weeks
•
Maintenance: 300-400 mg PO daily
Reduce maintenance dose to 200 mg orally daily if possible.
Indications for use
Labeled indications
Adults
•
Treatment of VF (life-threatening, recurrent, refractory)
•
Treatment of VT (life-threatening, recurrent, refractory, hemodynamically unstable)
Off-label indications
Adults
•
Treatment of AF (rate control)
•
Treatment of fetal tachycardia
•
Treatment of SVT (ongoing management)
•
Prevention of AF, in patients undergoing cardiac surgery
•
Secondary prevention of ventricular arrhythmias in patients with ischemic heart disease (recurrent, significant symptoms or ICD shocks)
•
Secondary prevention of ventricular arrhythmias in patients with nonischemic cardiomyopathy (recurrent, significant symptoms or ICD shocks)
Safety risks
Boxed warnings
Cardiac toxicity
•
Maintain a high level of suspicion, as amiodarone can exacerbate arrhythmias or cause new VF, incessant VT, increased resistance to cardioversion, and polymorphic VT associated with QT prolongation. Initiate amiodarone in a setting where continuous ECG and cardiac resuscitation are available. Correct hypokalemia, hypomagnesemia, and hypocalcemia before initiating treatment.
Hepatotoxicity
•
Maintain a high level of suspicion, as amiodarone has been associated with an increased risk of hepatotoxicity. Obtain baseline and periodic liver transaminases. Discontinue or reduce dose if transaminases exceed three times normal or doubles in a patient with an elevated baseline.
Pulmonary toxicity
•
Maintain a high level of suspicion, as amiodarone has been associated with an increased risk of pulmonary toxicity, particularly hypersensitivity pneumonitis, eosinophilic pneumonia, and interstitial/alveolar pneumonitis. Cases of postoperative adult respiratory distress syndrome have also been reported. Obtain a baseline CXR and pulmonary function tests, including diffusion capacity, when amiodarone is initiated. Repeat history, physical examination, and CXR every 3-6 months.
Contraindications
Hypersensitivity to amiodarone or its components, including iodine
Cardiogenic shock
Corneal refractive laser surgery
•
Advise patients that most manufacturers of corneal refractive laser surgery devices contraindicate corneal refractive laser surgery in patients taking amiodarone.
Warnings and precautions
Amiodarone-induced thyroid disorders
•
Use caution, as amiodarone can cause thyroid abnormalities, including hyperthyroidism and hypothyroidism.
Bradycardia
•
Maintain a high level of suspicion, as amiodarone can causes symptomatic bradycardia or sinus arrest, especially in the presence of electrolytic disorders or concomitant use of antiarrhythmics or negative chronotropes.
Conduction disorders
•
Use caution in patients undergoing surgery, as amiodarine may increase sensitivity to the myocardial depressant and conduction effects of halogenated inhalational anaesthetics.
Interference with implanted cardiac devices
•
Use caution in patients with implanted defibrillators or pacemakers, as chronic use of antiarrhythmic drugs may affect pacing and defibrillation thresholds.
Peripheral neuropathy
•
Maintain a high level of suspicion, as amiodarone has been associated with an increased risk of peripheral neuropathy.
Persistence of adverse effects
•
Maintain a high level of suspicion, as adverse reactions and drug interactions can persist for several weeks after discontinuation due to the long half-life of amiodarone.
Photosensitivity of skin, skin discoloration
•
Maintain a high level of suspicion, as amiodarone can induce photosensitization and cause blue-gray discoloration of the skin with long-term use.
Visual disturbances
•
Maintain a high level of suspicion, as amiodarone has been associated with an increased risk of optic neuropathy, optic neuritis, and corneal microdeposits.
Specific populations
Renal impairment
eGFR 0-90 mL/min/1.73 m²
•
Use acceptable. No dose adjustment required.
Renal replacement therapy
Continuous renal replacement
•
Use acceptable. No dose adjustment required.
Intermittent hemodialysis
•
Use acceptable. No dose adjustment required.
Peritoneal dialysis
•
Use acceptable. No dose adjustment required.
Hepatic impairment
Any severity
•
Use with caution. Monitor serum aminotransferases. Discontinue or reduce dose if transaminases exceed three times normal or doubles in a patient with an elevated baseline.
Pregnancy and breastfeeding
Pregnancy
All trimesters • Australia Category: C
•
Consider safer alternatives. Evidence of fetal harm in humans. Monitor fetal growth. Monitor neonates for bradycardia, hypothyroidism and hyperthyroidism. Use amiodarone only for the treatment of life-threatening arrhythmias when other treatments are ineffective or contraindicated.
Breastfeeding
Do not use during breastfeeding.
Low levels in breastfed infants (5-25%).
May potentially cause adverse effects in breastfed infants.
Adverse reactions
Very common > 10%
•
Nausea, vomiting
Common 1-10%
•
Congestive heart failure, cardiac arrhythmias, sinus node dysfunction, pulmonary fibrosis, hypothyroidism, hyperthyroidism, constipation, loss of appetite, abdominal pain, photosensitivity of skin, malaise, fatigue, tremor, involuntary movements, incoordination, gait disturbance, ataxia, dizziness, paresthesia, insomnia, ↓ libido, headache, sleeping disorder, visual disturbances, ↑ LFTs, skin flushing, change in taste, change in smell, hypersalivation, coagulopathy
Uncommon < 1%
•
Conduction disorders, skin rash, ecchymosis, blue skin discoloration, hypotension, hair loss
Unknown frequency
•
Anaphylactoid reactions, anaphylaxis, idiopathic intracranial hypertension, chronic inflammatory demyelinating polyneuropathy, sinus arrest, acute respiratory distress syndrome, bronchiolitis obliterans organizing pneumonia, diffuse alveolar hemorrhage, acute pancreatitis, liver cirrhosis, hepatitis, cholestasis, toxic epidermal necrolysis, erythema multiforme, Stevens-Johnson syndrome, exfoliative dermatitis, DRESS syndrome, skin cancer, rhabdomyolysis, renal failure, epididymitis, thyroid nodules, syndrome of inappropriate antidiuretic hormone secretion, vasculitis, thyroid cancer, hypersensitivity pneumonitis, hemolytic anemia, aplastic anemia, interstitial lung disease, pancytopenia, ↓ blood neutrophil count, ↓ platelet count, agranulocytosis, angioedema, akinesia, bradykinesia, parkinsonism, hallucinations, confusion, disorientation, delirium, bronchospasm, pleural effusion, pleuritis, urticaria, pruritus, lupus-like symptoms, muscle weakness, myopathy, renal dysfunction, erectile dysfunction, dry mouth, fever, peripheral neuropathy, bradycardia, VF, ↑QT interval
Interactions
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