From the Guidelines
Amiodarone should be administered with a loading dose of 400-600 mg daily in divided doses for 2-4 weeks, followed by a maintenance dose of 100-200 mg daily. This dosing regimen is based on the most recent and highest quality study available, which prioritizes minimizing long-term adverse effects while maintaining therapeutic efficacy 1. The loading dose can be up to 1200 mg daily in an inpatient monitoring setting, but the maintenance dose should not exceed 200 mg daily.
Key Considerations
- The dosing regimen aims to achieve therapeutic levels quickly with the loading dose while minimizing side effects with the lower maintenance dose.
- Amiodarone has an extremely long half-life due to its lipophilic nature and tissue accumulation, which allows for once-daily maintenance dosing but also means that side effects may persist long after discontinuation.
- Regular monitoring of liver function, thyroid function, and pulmonary status is essential during amiodarone therapy due to potential toxicity.
- Patients should also be advised to use sun protection as amiodarone can cause photosensitivity reactions.
Potential Adverse Effects
- Bradycardia
- QT prolongation
- Torsades de pointes (rare)
- Gastrointestinal upset
- Constipation
- Hypothyroidism
- Hyperthyroidism
- Pulmonary fibrosis
- Hepatic toxicity
- Corneal deposits
- Optic neuritis
- Peripheral neuropathy
- Photosensitivity
Precautions and Interactions
- Sinus or AV conduction disease (in absence of pacemaker)
- Inflammatory lung disease
- Hepatic dysfunction
- Hypothyroidism, hyperthyroidism
- Peripheral neuropathy
- Abnormal gait/ataxia
- Optic neuritis
- Drugs with SA and/or AV nodal–blocking properties
- Amiodarone is a substrate of and inhibits P-glycoprotein and CYP2C9 (moderate), CYP2D6 (moderate), and CYP3A4 (weak); amiodarone is a substrate for CYP3A4 (major) and CYP2C8 (major); amiodarone is an inhibitor of OCT2
- Reduce warfarin dose by 50%, and reduce digoxin dose by 30%–50% 1.
From the FDA Drug Label
DOSAGE & ADMINISTRATION Amiodarone shows considerable interindividual variation in response. Thus, although a starting dose adequate to suppress life-threatening arrhythmias is needed, close monitoring with adjustment of dose as needed is essential The recommended starting dose of amiodarone HCl injection is about 1000 mg over the first 24 hours of therapy, delivered by the following infusion regimen: After the first 24 hours, the maintenance infusion rate of 0. 5 mg/min (720 mg/24 hours) should be continued utilizing a concentration of 1 to 6 mg/mL
The typical dosing regimen for Amiodarone is:
- Initial dose: 1000 mg over the first 24 hours of therapy
- Maintenance dose: 0.5 mg/min (720 mg/24 hours) after the first 24 hours
- Concentration: 1 to 6 mg/mL, with concentrations greater than 2 mg/mL administered via a central venous catheter 2
- Supplemental dose: 150 mg infusions may be administered over 10 minutes in the event of breakthrough episodes of VF or hemodynamically unstable VT
- Maximum dose: Mean daily doses above 2100 mg were associated with an increased risk of hypotension 2
From the Research
Amiodarone Dosing Regimen
The typical dosing regimen for Amiodarone, an antiarrhythmic medication, varies depending on the specific condition being treated and the patient's response to the medication.
- For patients with recurrent supraventricular tachycardia or atrial fibrillation, maintenance doses of 100 to 400 mg/day are often effective 3.
- For patients with chronic ischemic heart disease and "warning" ventricular arrhythmias, moderate doses of 400 mg/day can be highly effective in suppressing ventricular couplets, runs of ventricular tachycardia (VT), and the "R on T" phenomenon 3.
- For the treatment and prevention of sustained recurrent VT and malignant arrhythmias, higher doses of around 800 mg/day may be required 3.
Loading Dose and Maintenance Therapy
- A loading dose of 800 mg/day for 6 weeks, followed by a maintenance dose of 600 mg/day, has been used in patients with sustained, symptomatic ventricular tachycardia (VT) or cardiac arrest 4.
- High-dose oral loading regimens, such as 50 mg/kg per day for 3 days, then 30 mg/kg per day for 2 days, followed by maintenance therapy of 300 to 400 mg twice daily, have also been used in patients with recurrent ventricular arrhythmias 5.
Dose Adjustment and Side Effects
- The dose of Amiodarone may need to be adjusted based on clinical response, side effects, and plasma drug levels 6.
- Common side effects of Amiodarone include tremor, nausea, visual disturbances, thyroid function abnormalities, and pulmonary interstitial infiltrates 4, 6.
- Despite the potential for side effects, many patients can be successfully managed with Amiodarone, with some studies reporting long-term efficacy and safety with doses ranging from 100 to 600 mg/day 6, 7.