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- Thyroid Symptoms and Solutions Slideshow Pictures
- What is methimazole, and how does it work (mechanism of action)?
- What brand names are available for methimazole?
- Is methimazole available as a generic drug?
- Do I need a prescription for methimazole?
- What are the side effects of methimazole?
- What is the dosage for methimazole?
- Which drugs or supplements interact with methimazole?
- Is methimazole safe to take if I'm pregnant or breastfeeding?
- What else should I know about methimazole?
What is methimazole, and how does it work (mechanism of action)?
Methimazole is used to treat an overactive thyroid gland (hyperthyroidism). Grave's disease is the most common cause of hyperthyroidism. Grave's disease is an autoimmune disease resulting from antibodies that attach to receptors on thyroid hormone-producing cells in the thyroid gland and trigger overproduction of thyroid hormone. An enzyme (peroxidase) produces thyroid hormones, i.e., thyroxine (T4) and triiodothyronine (T3), by combining iodine with a protein called thyroglobulin. Methimazole prevents iodine and peroxidase from their normal interactions with thyroglobulin to form T4 and T3. This action decreases thyroid hormone production. Methimazole also interferes with the conversion of T4 to T3. Since T3 is more potent than T4, this also reduces the activity of thyroid hormones. The FDA approved methimazole in March 1999.
What brand names are available for methimazole?
Tapazole, Northyx (discontinued)
Is methimazole available as a generic drug?
Do I need a prescription for methimazole?
What are the side effects of methimazole?
Methimazole is generally well-tolerated with side effects occurring in 3 out of every 100 patients. The most common side effects are related to the skin and include:
Other common side effects are:
Less common but more serious side effects include a decrease in white blood cells (agranulocytosis) and blood platelets (thrombocytopenia). Symptoms and signs of agranulocytosis include infections of the throat, the gastrointestinal tract, and skin with an overall feeling of illness and fever. Since platelets are important for the clotting of blood, thrombocytopenia may lead to problems with excessive bleeding. Hepatitis and death of liver cells (hepatic necrosis) have rarely been associated with methimazole.
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