Amiodarone

Amiodarone

CLASSIFICATION: Class III anti-arrhythmic agent

PRESENTATION: 150mg/3mL ampoule-  Cardarone 100mg, 200mg tablet

INDICATION: Treatment and prophylaxis of serious atrial and ventricular tachyarrhythmias and SVT refractory to other therapy  

DOSAGE AND ADMINISTRATION: 

IV Bolus: 150-300mg diluted in 10-20mL glucose 5% administered slowly over 1-2 minutes (Extreme emergency (ie. resus situation) only)

Continuous IV Infusion: Loading dose: 300mg in 250mL glucose 5% infused over 20-60 minutes (= approx 5mg/kg)

Maintenance dose: 600mg in 250mL glucose 5% infused over 12 hours. This may be repeated. Usual suggested maximum dose over 24 hours is 1200mg (ie. approx 15mg/kg). In fluid restricted patients, dose may be diluted in 100mL glucose 5%. 

NB. Minimum stable concentration = 150mg in 250mL glucose 5%. 

* Supplemental bolus doses (eg. 150mg over 10-30 minutes) may be administered at the discretion of the attending physician based on clinical urgency.

Oral: may be used as a loading dose regimen, typically: 

• 200-400mg three times a day for one week, then 
• 200mg twice a day for one week, then 
• 100-200mg daily. 
• A single oral dose of 1g followed by maintenance dose is also used.
• After IV loading- 200mg twice or three times a day for one week then 100-200mg daily.

ADVERSE EFFECTS: 

Acute:  

• Cardiovascular collapse,  
• Bradycardia with heart block, 
• Hypotension, 
• Hot flushes, 
• Nausea, 
• Sweating (usually associated with rapid IV infusion).

Chronic:  

• Increases in liver transaminases, 
• Photosensitivity; 
• Bluish-grey skin discolouration, 
• Hypothyroidism or hyperthyroidism, 
• Pulmonary fibrosis or alveolitis Corneal micro-deposits (benign), 
• Optic neuritis, 
• Peripheral neuropathy  

Other:           

• Atypical ventricular tachycardia (torsade de pointes) uncommon, although QT prolongation occurs frequently

PRECAUTIONS:      

Amiodarone consists a specific iodine content and should be used with

EXTREME  CAUTION in patients with true iodine allergies. Literature reports indicate use in such

patients is possible, but cross-sensitivity has occurred. 

Can cause severe thrombophlebitis when given through a peripheral line. 

INFUSION VIA A LONG LINE OR CVL IS PREFERABLE. 

Absorption into PVC containers occurs over time. Prepare infusions immediately before use and 

use within 12 hours. 

Incompatible with sodium chloride 0.9%- use glucose 5% only. 

Use in a critical care facility where continuous cardiac monitoring can be performed or 

defibrillation initiated immediately is highly preferable, but not essential. Hardwire monitoring is 

preferred during the bolus infusion or if the patient is unstable. 

Do not use in pregnancy or lactation. 

In patients in whom bradycardia or AV block is sufficient to cause syncope, amiodarone should 

only be used in conjunction with a pacemaker. 

If hypotension or other cardiac irregularity occurs during infusion, a reduction in flow rate may 

be sufficient to correct this. In cases of severe hypotension or bradycardia, see recommendations 

below. 

NURSING IMPLICATIONS: 

• Infusion administered too rapidly may precipitate circulatory collapse (see Precautions). 
• Moderate, but transient, reduction in blood pressure may be observed. 
• Be alert for flushing, nausea and sweating. 
• Observe IV bung site frequently if being administered peripherally. 
• Do not admix in the bag or line with other drugs.

 Record blood pressure and pulse:

1.    at commencement and cessation of bolus dose

2.    hourly for the next FOUR hours

3.    if the patient is stable, TWO hourly until the completion of the first 12 hour infusion

4.    FOUR hourly if a second 12 hour infusion is commenced and the patient is stable.

Due to the slow and variable oral absorption of amiodarone, concurrent intravenous and oral administration is acceptable (especially in patients in whom there is concern about gastrointestinal absorption). References refer to the possibility of overlapping therapy by up to 48 hours. This is a clinical decision based on each individual patient’s response to therapy and may not be necessary in all patients.

 

Bradycardia and Hypotension Guidelines for Concurrent IV and Oral Amiodarone Therapy for Cardiothoracic Patients on 8 North. 

Patients who demonstrate bradycardia (HR < 60 BPM) or hypotension (SBP < 90mmHg) during concurrent therapy may require medical review. If the patient is stable, complete the following steps first prior to calling the medical officer: 

• Cease amiodarone infusion for ONE hour.
• If after one hour the patient remains bradycardic and/or hypotensive, contact the Cardiothoracic 
• registrar.
• If the patient is unstable during this time, call 55 immediately.
• If after ONE hour the blood pressure has improved (SBP>90mmHg) and/or the bradycardia has 
• resolved, recommence the amiodarone infusion at HALF the initial prescribed rate but withhold 
• the next oral dose until medical review.

If the morning dose is omitted and the patient is stable, it is acceptable to wait for the morning  

Cardiothoracic team review.

DRUG INTERACTIONS: 

Warfarin- may increase INR; lower dose of warfarin may be required 

Digoxin- digoxin concentrations may increase by 70%; halving of the digoxin dose is suggested 

Beta-blockers, calcium channel blockers- combined use may give rise to bradycardia 

Class 1A anti-arrhythmic agents- increased risk of Torsade de pointes or other toxicities 

Other drugs that cause QT prolongation 

Potassium depleting drugs (eg. diuretics, laxatives) 

Cyclosporin, phenytoin- increased levels and toxicity possible