methimazole /məthim″əzōl/ , an orally administered antithyroid drug. ▪ INDICATIONS: It is prescribed in the treatment of hyperthyroidism. ▪ CONTRAINDICATIONS: Use in nursing mothers, because it is excreted in milk, and known hypersensitivity to the drug prohibit its use. ▪ ADVERSE EFFECTS: Agranulocytosis, leukopenia, thrombocytopenia, and aplastic anemia may occur.