Amiodarone

Question 1

Indications ?

Answer 1

Indicated in a range of tachyarrhythmias : SVT, VT, AF and refractory ventricular fibrillation VF. Generally only used when other options have failed. It is a dangerous molecule that should only be prescribed when the risk-benefit balance justifies it, it has many AE when used chronically & an extremely long half-life.

Question 2

Mechanism of action ?

Answer 2

Blockade of Na, Ca &K channels and antagonism of a and b adrenoceptors. It reduces spontaneous depolarisation (automaticity), increases resistance to depolarisation and reduces conduction velocity (dromotrope -).

Question 3

Important AE ?

Answer 3

AmIODarone is similar in structure to thyroid hormones &has iode in it : hypo/hyperthyroidism,
When chronically used, it has many side effects on : lungs, heart, liver, skin &thyroid gland. Pneumonitis, bradycardia &AV block, hepatitis, photosensitivity &grey discolouration

Question 4

Important interactions ?

Answer 4

it increases concentrations of : Digoxin, Diltiazem &Verapamil. Their doses should be halved when associated to Amiodarone

Question 5

Important cautions (counselling)

Answer 5

Do not drink grapefruit juice when on Amiodarone,
Avoid direct sun exposure,
Declare breathlessness, restlessness, jaundice &tiredness.
For monitoring : Chest X-ray, renal, liver &thyroid profiles are baseline tests that ought to be repeated 6-monthly.