Amiodarone

Question 1

Indications

Answer 1

• Cardiac arrest with VF or VT at any time after the first dose of adrenaline.
• Adults with sustained VT in the absence of cardiac
  arrest.
• Adults with moderate cardiovascular compromise
  as a result of fast atrial fibrillation or fast atrial
  flutter.

Question 2

Contraindications and cautions

Answer 2

Contraindications:
- Known severe allergy.

• Known severe allergy to iodine.
• VT secondary to cyclic anti-depressant poisoning.
  In this setting amiodarone administration can be associated with severe worsening of shock,
  without resolution of the rhythm.

Cautions:
- None if the patient is in cardiac arrest.

• Poor perfusion or signs of low cardiac output. Amiodarone reduces inotropy and may cause
  significant fall in cardiac output, particularly when
  administered rapidly.
• Hypotension. Amiodarone causes vasodilation and may worsen hypotension, particularly when administered rapidly.
• Atrial fibrillation associated with severe sepsis. Amiodarone may cause a significant fall in cardiac
  output.
• Sick sinus
• 2nd or 3rd degree heart blocks
• Pregnancy

Question 3

Actions

Answer 3

Amiodarone is an antidysrhythmic with a broad spectrum of activity. It has predominantly class III activity. It prolongs the action potential duration, reduces automaticity and prolongs the refractory
period of atrial, nodal and ventricular tissues.

The electrophysiological effects result in a reduction in abnormal electrical activity (for example ectopy), a reduction in electrical conduction, a reduction in heart rate, and a stabilisation of the SA and AV nodes.

Amiodarone also causes a small increase in coronary blood flow (although this is not usually clinically significant) and a reduction in myocardial oxygen consumption by reducing inotropy (the force of cardiac conduction).

Question 4

Route

Answer 4

IV
IO

Question 5

Dosage:

Answer 5

Adults:
CA: 300mg first dose,
150mg second after 15 minutes

Infusion for tachydyrhthmias:
- 300mg in 100mg 5% glucose given over 30 minutes
- 300mg in 50ml via infusion

Question 6

Side effects

Answer 6

Common adverse effects:
– Hypotension.
– Light headedness.
– Bradydysrhythmia.

Amiodarone may potentiate the action of cyclic antidepressants in cyclic poisoning.

Amiodarone may cause bradycardia following reversion if the patient is on a beta- blocker and/ or a centrally acting calcium channel blocker (for
example diltiazem).