Management of amiodarone-related thyroid problems

Amiodarone is a highly effective and well-established antiarrrhythmic drug. It can be used to treat supraventricular and ventricular tachyarrhythmias and has the added advantage of being well tolerated in patients with impaired left ventricular systolic function with a low incidence of arrhythmic events, such as torsades de pointes. However, owing to its marked lipid affinity, it is highly concentrated in tissues and is linked to a number of adverse effects, including thyroid dysfunction. Amiodarone can lead to both hypothyroidism (amiodarone-induced hypothyroidism) and less commonly hyperthyroidism (amiodarone-induced thyrotoxicosis) and relates to high iodine content within the molecule as well as to several unique intrinsic properties of amiodarone. Dronedarone is a recently approved antiarrhythmic drug. It is structurally very similar to amiodarone, however the iodine moiety, present with amiodarone has been removed and replaced with a methylsulfonamide group to reduce fat solubility and adverse effects. We present an overview of the effects of amiodarone on thyroid function and the treatment options available, as well as a brief insight into dronedarone and its potential as an alternative to amiodarone.