GENERIC NAME: methimazole

BRAND NAME: Tapazole

DRUG CLASS AND MECHANISM: Methimazole is used to manage hyperthyroidism (overactivity of the thyroid gland). It is considered an antithyroid agent, like propylthiouracil (PTU).

Grave's disease is the most common cause of hyperthyroidism. It is an autoimmune disease in which an individual's own antibodies attach to thyroid stimulating hormone receptors within thyroid cells and thereby trigger overproduction of thyroid hormones. The two thyroid hormones manufactured by the thyroid gland, thyroxine (T4 ) and triiodothyronine (T3), are formed by combining iodine with a protein called thyroglobulin with the assistance of an enzyme called peroxidase. Methimazole inhibits 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, and, since T3 is more potent than T4, this also reduces the activity of thyroid hormones.)

GENERIC AVAILABLE: no

PRESCRIPTION: yes

PREPARATIONS: Tablet: 5 mg and 10 mg.

STORAGE: Methimazole should be stored at room temperature, 15-30°C (59-86°F).

PRESCRIBED FOR: Methimazole is used to manage hyperthyroidism associated with Grave's disease. It is also used to decrease symptoms of hyperthyroidism in preparation for surgically removing the thyroid gland or before inactivating the thyroid gland with radioactive iodine.

DOSING: The initial adult dose of methimazole is 15 mg/day for mild hyperthyroidism, 30-40 mg/day for moderately severe hyperthyroidism and 60 mg/day for severe hyperthyroidism. The drug is usually taken every eight hours but may be taken once daily under physician supervision. A common, long-term, adult dose after initial treatment is 5-30 mg/day. Children's initial and continuing doses vary.

DRUG INTERACTIONS: There are no known drug interactions with methimazole.

PREGNANCY: There is evidence that methimazole may cause harm to the fetus during pregnancy.

NURSING MOTHERS: There is evidence that methimazole may cause harm to the fetus during nursing.

SIDE EFFECTS: 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 rash, itching, hives, abnormal hair loss, and skin pigmentation. Other common side effects are swelling, nausea, vomiting, heartburn, loss of taste, joint or muscle aches, numbness and headache.

Less common but serious side effects have occurred with methimazole therapy. A decrease of white blood cells in the blood (agranulocytosis) may occur. Symptoms and signs of agranulocytosis include infectious lesions of the throat, the gastrointestinal tract and skin with an overall feeling of illness and fever. A decrease in blood platelets (thrombocytopenia) also may occur. Since platelets are important for the clotting of blood, thrombocytopenia may lead to problems with excessive bleeding.

There also have been rare occurrences with methimazole of hepatitis and death of liver cells (hepatic necrosis). Failure of the liver due to hepatic necrosis may lead to severe brain swelling, gastrointestinal bleeding, and death.

From the Doctors at MedicineNet.com

propylthiouracil - Emphasizes the medication propylthiouracil, a drug used to manage hyperthyroidism. Source:MedicineNet Hypothyroidism - Learn about Hypothyroidism (underactive thyroid) including causes, symptoms (such as weight gain, fatigue, and depression), diagnosis, and treatment. Source:MedicineNet Thyroid Blood Tests - Read about thyroid blood tests, which are used to diagnose disease of the thyroid such as hyperthyroidism and hyperthyroidism, as well as point to other diseases of the thyroid gland. Source:MedicineNet Read 23 more methimazole related articles ... Scoliosis: An Unnatural Curve Nasal Irrigation Can Help Fight Spring Allergies Health Highlights: May 11, 2008 Aging Hands? Docs Put Beauty Within Reach Banishing Wrinkles With Fillers Body Contouring Surgery Improves Acrylamide in Diet: Cancer Risk? Newer Prostate Cancer Treatment Similar to Traditional Surgery Protective Eyewear Key to Sports Safety Health Tip: Coping With Alzheimer's