Propylthiouracil and carbimazole are antithyroid drugs used for the management of hypothyroidism. They lead to a reduction in thyroid hormone synthesis through inhibition of thyroperoxidase, subsequently preventing the iodination of thyroglobulin. The drugs are administered orally and are rapidly absorbed from the gastrointestinal tract. They concentrate in the thyroid gland, and their duration of action is closely related to the intrathyroidal drug concentration, rather than plasma half-life. The elimination half-life may be increased in hepatic and renal impairment.