Methimazole

Generic name: methimazole [ me-THIM-a-zole ]
Brand names: Tapazole, Northyx

Drug class: Antithyroid agents

Dosage form: Tablet

Route of administration: Oral

Dose: 5 mg, 10 mg

Mechanism of action: Methimazole inhibits the synthesis of thyroid hormones by blocking the oxidation of iodine in the thyroid gland, thereby reducing the production of thyroxine (T4) and triiodothyronine (T3).

Drug usage cases: Methimazole is used to treat hyperthyroidism, including Graves’ disease, and to prepare the thyroid gland for surgery or radioactive iodine therapy.

Drug contra indications: Methimazole should not be used in patients with known hypersensitivity to the drug or any component of the formulation. It is also contraindicated in patients with severe liver disease.

Side effects: Common side effects include rash, nausea, vomiting, and headache. Serious side effects may include:

• Agranulocytosis: Risk of severe reduction in white blood cell count.
• Hepatotoxicity: Potential for liver enzyme elevation and liver damage.
• Vasculitis: Inflammation of blood vessels.
• Hypothyroidism: Risk of underactive thyroid with prolonged use.

Warnings: Methimazole can cause agranulocytosis and severe liver damage. Blood counts should be monitored regularly, and patients should be advised to report any signs of infection or jaundice. It can also lead to hypothyroidism, requiring adjustment of the dose.

Use during pregnancy or breastfeeding: Methimazole should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It is excreted in human milk, so caution should be exercised when administered to breastfeeding mothers.