Amiodarone

Amiodarone is generally thought to be the most effective anti-arrhythmic drug available. It can be used to treat atrial fibrillation as well as ventricular tachycardia (an abnormal heart rhythm from the bottom chamber of the heart). It is a very useful drug that can be used in a number of situations, for example in patients with cardiac failure and coronary artery disease.

Mechanism of action

Amiodarone acts by blocking sodium and potassium channels in the heart muscle, slowing electrical conduction and prolonging the heart’s recovery period.  It can be given through the veins intravenously or orally in tablet form.  The drug has a long half-life (approximately 58 days) so can take several months to become effective and to be eliminated by the body if it is stopped.

Potential side-effects

Unfortunately despite its uses Amiodarone also has a number of side-effects including: sensitivity to the sun, thyroid gland dysfunction (40%), visual impairment due to reversible corneal deposits, liver dysfunction, paraesthesia (or tingling) in the fingers/toes and pulmonary fibrosis (scarring of the lungs). If you are on Amiodarone you will be required to have regular liver and thyroid function tests every 6-12 months.

Interactions

Amiodarone also interacts with a number of medications.  The most common interactions to be aware of are with Warfarin and Digoxin. Doses of both of these medications will need to be reduced when taking Amiodarone.  In particular if you are on Warfarin you will need to have your INR levels monitored closely when Amiodarone is initiated.

More information

Amiodarone Surveillance for patients taking this medication >12 months