Amiodarone, Injection

1. Health Canada Product Monograph — Amiodarone, Injection

• Emergency treatment of documented, life-threatening, recurrent ventricular fibrillation or hemodynamically unstable ventricular tachycardia refractory to other therapy.
• First-line antiarrhythmic during cardiopulmonary resuscitation for shock-refractory ventricular fibrillation or pulseless ventricular tachycardia, alongside defibrillation and epinephrine.
• Control of hemodynamically stable but drug-refractory monomorphic ventricular tachycardia.
• Not appropriate for polymorphic ventricular tachycardia/torsades de pointes — amiodarone itself prolongs the QT interval; magnesium sulfate is the treatment of choice for that arrhythmia instead.

• Crosses the placenta and can cause fetal or neonatal thyroid dysfunction (goiter, hypothyroidism, or hyperthyroidism) and bradycardia with sustained use.
• Reserve non-emergency use for situations where the expected maternal benefit clearly outweighs the fetal risk; a genuine cardiac-arrest or life-threatening arrhythmia indication is never deferred because of pregnancy.

• Excreted into breast milk in clinically significant amounts given the drug's very long half-life.
• A single emergency resuscitation dose is not a reason to withhold treatment, but breastfeeding should be interrupted afterward, and continued outpatient use is generally incompatible with breastfeeding.

• Clinical experience has not identified a systematic difference in response between older and younger patients, but dose selection should start at the low end of the range, reflecting the greater likelihood of reduced hepatic, renal, or cardiac function and of interacting medications.

• Health Canada has not authorized a pediatric indication for this product. Pediatric weight-based antiarrhythmic dosing exists within resuscitation protocols but should be directed by pediatric emergency medicine or cardiology specialists, not this general reference.

• Cardiac arrest (pulseless VT/VF, shock-refractory): 300 mg IV/IO bolus; may give an additional 150 mg IV/IO bolus if the arrhythmia persists or recurs after further defibrillation attempts.
• Perfusing, hemodynamically stable ventricular arrhythmia — rapid loading infusion: 150 mg over 10 minutes (approximately 15 mg/minute); the initial infusion rate should not exceed 30 mg/minute because of the hypotension risk.
• Slow loading infusion, immediately following the rapid loading dose: 360 mg over the next 6 hours (approximately 1 mg/minute).
• Maintenance infusion: 540 mg over the next 18 hours (approximately 0.5 mg/minute); this rate can be cautiously continued for up to 2–3 weeks if ongoing IV therapy is required.
• Administer through a central line where possible to reduce the risk of phlebitis; if only peripheral access is available, use the largest suitable vein and rotate the infusion site regularly.
• Transition to oral amiodarone once the rhythm is stable and IV therapy is being tapered, following a specific oral-overlap schedule.

If overdose is suspected, seek emergency medical attention immediately or contact your regional Poison Control Centre without delay.

• No specific antidote exists. Treatment is supportive: manage hypotension, bradycardia, and AV block with vasopressors/inotropes and temporary pacing, and slow or stop the infusion.
• Amiodarone and its major metabolite are not removed by dialysis.

• Hypotension, especially with rapid infusion.
• Injection-site reactions and phlebitis, particularly with peripheral administration.
• Nausea, bradycardia.

Serious side effects require immediate discussion with the prescriber or emergency care.

• Pulmonary toxicity (hypersensitivity pneumonitis or interstitial/alveolar pneumonitis), which can be fatal.
• Hepatotoxicity, usually mild transaminase elevation but rarely severe liver injury.
• Proarrhythmia — amiodarone can make the treated arrhythmia less well tolerated or more difficult to reverse, or cause new significant bradycardia or heart block.
• Cardiogenic shock and severe, sometimes precipitous, hypotension.

• Pre-existing hepatic impairment, thyroid disease, or severe pulmonary disease.
• Concurrent use of other QT-prolonging drugs or other agents that slow AV conduction (beta-blockers, non-dihydropyridine calcium channel blockers, digoxin).

• Known hypersensitivity to amiodarone or any component of the product, including iodine.
• Cardiogenic shock.
• Severe sinus-node dysfunction causing bradycardia, or second- or third-degree AV block, unless a functioning pacemaker is in place.
• History of bradycardia-related syncope without a pacemaker.

• Reduce digoxin dose by approximately 50% when starting amiodarone, and monitor digoxin levels.
• Amiodarone inhibits warfarin metabolism — reduce the warfarin dose and monitor INR closely after starting or stopping amiodarone.
• Additive bradycardia and AV block with beta-blockers and non-dihydropyridine calcium channel blockers.
• Raises levels of many CYP3A4 and CYP2C9 substrates (e.g., simvastatin, cyclosporine, phenytoin).
• Avoid combining with other QT-prolonging drugs given amiodarone's own QT effect.
• Life-threatening bradycardia has been reported when combined with certain hepatitis C direct-acting antivirals (e.g., sofosbuvir-based regimens).

• Not applicable to the intravenous formulation beyond standard IV-line compatibility — do not co-infuse with other drugs in the same line unless compatibility is confirmed.

• Hospital or monitored setting only, administered by infusion pump with continuous ECG and blood pressure monitoring.

• Store per product-specific labelled conditions and protect from light.
• Do not use if the solution is discoloured or contains particulate matter.
• Use the administration set material specified in the product monograph, since the concentrated solution can leach plasticizer from some PVC tubing during prolonged infusion.

• This is a hospital-administered emergency antiarrhythmic used to treat life-threatening ventricular arrhythmias.
• On transition to oral amiodarone, the same long-term monitoring required for chronic therapy (thyroid, liver, lung, and eye checks) applies, along with counselling about the drug's very long duration of action and extensive interaction profile.