Adult: Initially, 5 mg/kg via infusion over a period of 20-120 minutes, may repeat infusion up to 1,200 mg (approx 15 mg/kg) per 24 hours, with a rate of infusion adjusted based on clinical response. For emergency cases: 150-300 mg via slow inj over ≥3 minutes, may be repeated at least 15 minutes after the first dose. Elderly: Use the minimum effective dose.
Adult: For cardiopulmonary resuscitation in cases that are resistant to defibrillation: Initially, 300 mg (or 5 mg/kg) via rapid inj. Additional 150 mg (or 2.5 mg/kg) may be given if ventricular fibrillation or pulseless ventricular tachycardia persists.
Adult: Initially, 200 mg tid for 1 week then reduced to 200 mg bid for another week. Maintenance: ≤200 mg daily based on patient response. Elderly: Use minimum effective dose.
Administration
May be taken with or without food. Take consistently w/ or w/o meals. Take w/ meals if high dose or to reduce GI discomfort.
Reconstitution
Supraventricular and ventricular arrhythmias: For initial infusion, dilute the required dose with 250 mL dextrose 5% solution, then 500 mL dextrose 5% solution for the succeeding infusion. Pulseless ventricular tachycardia or ventricular fibrillation resistant to defibrillation: Dilute required dose with 20 mL dextrose 5% solution.
Incompatibility
Incompatible with 0.9% NaCl solutions. Y-site admin: Incompatible with aminophylline, cefamandole nafate, cefazolin, mezlocillin, heparin, Na bicarbonate.
Contraindications
Sinus bradycardia, sino-atrial heart block, severe conduction disturbances (e.g. high-grade AV block, bifascicular or trifascicular block) without a presence of pacemaker, cardiogenic shock, severe hypotension, severe respiratory failure, known or history of thyroid dysfunction, known hypersensitivity to iodine, corneal refractive laser surgery. IV (bolus inj): Hypotension, heart failure, cardiomyopathy. Lactation. Concomitant use with drugs which may induce QT prolongation or torsades de pointes.
Special Precautions
Patient with latent or manifest heart failure, implantable cardioverter defibrillator or pacemaker, decompensated cardiomyopathy, hypotension. Patient undergoing surgery. Elderly. Pregnancy.
This drug may cause eye disorders, if affected, do not drive or operate machinery. Avoid excessive exposure to sunlight and use proper protective measures during treatment.
Monitoring Parameters
Monitor blood pressure, heart rate and rhythm (ECG), LFT, serum electrolytes (particularly K and Mg); pacing or defibrillation thresholds prior to and during treatment (in patients with implantable cardiac devices). Evaluate thyroid function tests prior to therapy and periodically (every 3-6 months) thereafter. Perform regular ophthalmologic examination, chest X-ray, and pulmonary function tests.
Overdosage
Symptoms: Sinus bradycardia, heart block, ventricular tachycardia attacks, torsades de pointes, circulatory failure, hepatic injury. Management: Symptomatic and supportive treatment. Perform gastric lavage to reduce absorption. Administer β-adrenergic agonists or glucagon if bradycardia occurs. Monitor cardiac status.
Drug Interactions
Increased concentration with inhibitors of CYP3A4 (e.g. HIV-protease inhibitors, cimetidine). Reduced concentration with inducers of CYP3A4 (e.g. rifampicin, phenytoin). May induce bradycardia with β-blockers, Ca channel blockers, and other antiarrhythmic drugs. May increase risk of arrhythmia with stimulant laxatives, diuretics, systemic corticosteroids. May increase concentration of ciclosporin, clonazepam, digoxin, flecainide, procainamide, quinidine, simvastatin, warfarin. May affect drugs that are P-glycoprotein substrates. Potentially Fatal: May cause prolongation of QT interval with fluoroquinolones, antipsychotics (e.g. chlorpromazine, thioridazine, fluphenazine), lithium, TCAs (e.g. doxepin, maprotiline, amitriptyline), halofantrine, and terfenadine.
Food Interaction
Increased plasma concentrations with grapefruit juice.
Action
Description: Mechanism of Action: Amiodarone is a class III antiarrhythmic agent but exhibits characteristics of all Vaughn-Williams classes. Its main effect is to lengthen the action potential and refractory period in the myocardial tissue. It blocks the Na, K, and Ca channels resulting in slowing of the conduction and prolongation of refractoriness. It produces negative chronotropic effect in nodal tissues similar to class IV. Onset: Oral: 2 days to 3 weeks. IV: Within hours (electrophysiologic); 2-3 days to 1-3 weeks (antiarrhythmic). Pharmacokinetics: Absorption: Variably and slowly absorbed from the gastrointestinal tract. Bioavailability: Oral: Approx 50% (range: 35-65%). Time to peak plasma concentration: 3-7 hours (oral). Distribution: Extensively distributed and accumulates in fat, skeletal muscles, and highly perfused tissues (e.g. liver, lung, spleen). Crosses the placenta and enters breast milk. Volume of distribution: Oral: 66 L/kg (range: 18-148 L/kg); IV: 40-84 L/kg. Plasma protein binding: >96%. Metabolism: Metabolised in the liver primarily by CYP3A4 and CYP2C8 to N-desethylamiodarone (active metabolite), may undergo enterohepatic recirculation. Excretion: Mainly via faeces, urine (<1% as unchanged drug). Elimination half-life: Amiodarone: 58 days (range: 15-142 days); N-desethylamiodarone: 36 days (range: 14-75 days).
Chemical Structure
Amiodarone Source: National Center for Biotechnology Information. PubChem Database. Amiodarone, CID=2157, https://pubchem.ncbi.nlm.nih.gov/compound/Amiodarone (accessed on Jan. 20, 2020)
Storage
Store between 20-25°C. Protect from light and moisture.
C01BD01 - amiodarone ; Belongs to class III antiarrhythmics.
References
Amiodarone 200 mg Tablets (Medreich Plc). MHRA. https://products.mhra.gov.uk. Accessed 19/05/2020.Amiodarone 30mg/mL Solution for Injection/Infusion in Pre-filled Syringe (Aurum Pharmaceuticals Ltd). MHRA. https://products.mhra.gov.uk. Accessed 19/05/2020.Amiodarone Injection, Solution (Fresenius Kabi USA LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 17/01/2020.Amiodarone Tablet (Cameron Pharmaceuticals, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 17/01/2020.Anon. Amiodarone. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 04/03/2021.Buckingham R (ed). Amiodarone. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/03/2021.Cordarone 150 mg/3 mL (Sanofi-Aventis [Malaysia] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 04/03/2021.Cordarone X 150 mg/3 mL Solution for Injection (Aventis Pharma Limited, Trading as Sanofi). MHRA. https://products.mhra.gov.uk. Accessed 04/03/2021.Joint Formulary Committee. Amiodarone Hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/03/2021.
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