What is the first line medication used for Graves' disease?

Methimazole is considered the first-line medication for the treatment of Graves' disease, a condition characterized by hyperthyroidism due to an overproduction of thyroid hormones. This medication functions as a thionamide, inhibiting the enzyme thyroid peroxidase, which plays a crucial role in the synthesis of these hormones. By blocking this enzyme, methimazole effectively reduces the production of thyroid hormones, leading to a decrease in the symptoms associated with hyperthyroidism.

Methimazole has a preferred profile compared to other medications used in this context, such as propylthiouracil, which is generally used in specific situations, like during the first trimester of pregnancy or in cases of severe liver disease. While carbimazole is also a thionamide similar to methimazole, it is considered a prodrug and is not as commonly used as methimazole in clinical practice outside certain regions. Levothyroxine, on the other hand, is a synthetic form of thyroid hormone and is not an appropriate treatment for hyperthyroidism; rather, it is used to treat hypothyroidism.

Utilizing methimazole allows for effective management of hyperthyroid symptoms with a favorable safety profile and a lower risk of adverse effects when compared to some alternatives.