Antithyroid Drugs

The thionamide drugs, i.e. carbimazole and its metabolite methimazole (MMI), andpropylthiouracil (PTU) have extensively been used in the management of various forms ofhyperthyroidism over the past eight decades. This review aims to summarize different aspectsof these outstanding medications. Thionamides have shown their own acceptable efficacy andeven safety profiles in treatment of hyperthyroidism, especially GD in both children and adultsand also during pregnancy and lactation. Of the antithyroid drugs (ATDs) available, MMI isthe preferred choice in most situations taking into account its better efficacy and less adverseeffects accompanied by once-daily dose prescription because of a long half-life and similar cost.Considering the more severe teratogenic effects of MMI, PTU would be the selected ATD fortreatment of hyperthyroidism during pre-pregnancy months and the first 16 weeks of gestation.Recent studies have confirmed the efficacy and safety of long-term MMI therapy with lowmaintenance doses for GD and toxic multinodular goiter. Despite the long-term history of ATDuse, there is still ongoing debate regarding their pharmacology and diverse mechanisms of action,viz. their immunomodulatory effects, and mechanisms and susceptibility factors to their adversereactions.