There is no difference between brand-name and generic drug formulations of amiodarone -- taken to control arrhythmia – in the incidence of thyroid dysfunction, according to a study in CMAJ (Canadian Medical Association Journal). Amiodarone, prescribed to control irregular heartbeats, is known for causing hypo- and hyper-thyroidism. Amiodarone is available in Canada in brand-name formulations as well as less costly generic versions. Generic formulations may be substituted if considered bioequivalent to the brand name drug. However, in some drugs there are concerns that generic formulas may be less effective or increase the number of adverse events.
