Tapazole (Methimazole)

Description

Tapazole, or Methimazole, is a medication used to treat hyperthyroidism, a condition characterized by an overactive thyroid gland that produces excessive thyroid hormone. This medication works by blocking the production of these hormones, thereby helping patients manage symptoms more effectively. Methimazole belongs to a class of drugs known as thionamides and is typically available in tablet form, with dosages of 5 or 10 mg. Patients often use this medication to alleviate the symptoms of hyperthyroidism or to prepare for thyroid surgery or treatment with radioactive iodine.

Directions

Take Methimazole by mouth with water, with or without food, following a healthcare provider’s directions. The total daily dosage is usually given in three divided doses at approximately 8-hour intervals: adults typically start with 15 mg for mild hyperthyroidism, 30 to 40 mg for moderate cases, and 60 mg for severe cases, while pediatric dosages are based on body weight. It’s important to take the medicine at the same times each day. If you forget a dose, take it as soon as you remember unless it’s almost time for your next one; don’t take two doses at once.

Ingredients

The active ingredient in Tapazole is Methimazole.

Contraindications

Avoid taking or using Methimazole if you have a known allergy to Methimazole or any component of the formulation.

Cautions

• Before using Tapazole, you may want to consult a healthcare provider about the following:
• Any existing health conditions
• Any allergies
• A list of all medications you are currently taking
• Whether you are pregnant or breastfeeding
• Tapazole crosses the placenta and may cause birth defects, especially in the first trimester of pregnancy. If you are pregnant or planning to become pregnant, talk to your doctor about alternative treatments. If Tapazole is necessary, the lowest effective dose should be used.
• Tapazole can cause a dangerous drop in white blood cells (agranulocytosis), which increases the risk of serious infections. Symptoms like fever, sore throat, or unusual fatigue should be reported to a doctor immediately. The medication should be stopped if blood disorders develop.
• In rare cases, Tapazole has been linked to liver damage, including acute liver failure. Watch for signs like loss of appetite, itching, upper right abdominal pain, or jaundice (yellowing of the skin or eyes) and seek medical help if they occur.
• Tapazole can lower thyroid hormone levels too much, leading to hypothyroidism. Regular blood tests are needed to monitor thyroid function and adjust the dose as needed.
• Tapazole can interact with blood thinners, beta-blockers, digitalis, and theophylline. If you take any of these medications, your doctor may need to adjust the dosage.
• Tapazole passes into breast milk but has not been shown to harm nursing infants when thyroid function is monitored regularly. Talk to your doctor before using this medication while breastfeeding.
• Tapazole is the preferred treatment for hyperthyroidism in children over other antithyroid drugs due to a lower risk of liver damage. However, close monitoring is still needed.

Side Effects

The most common side effects of Tapazole include nausea, vomiting, and mild stomach discomfort. Some patients may experience skin reactions such as rash, itching, or hives. Other minor side effects reported include headache, dizziness, drowsiness, or joint and muscle pain. These effects are usually mild and resolve with continued use.

Tapazole can cause rare but serious reactions, including severe blood disorders like agranulocytosis or thrombocytopenia, which can increase the risk of infection or bleeding. Liver problems, including hepatitis or jaundice, have also been reported. In rare cases, it may trigger lupus-like syndrome or inflammation of the kidneys (nephritis). Seek medical attention immediately if you experience symptoms such as persistent fever, unusual bruising, yellowing of the skin or eyes, or severe fatigue.

References

1. Tapazole (Methimazole) Product Monograph. Bristol, TN: King Pharmaceuticals, Inc.; 2012.
2. Tapazole (Methimazole) Drug Label Information. Philadelphia, PA: United Research Laboratories, Inc.; 2007.

About Dr. Gerardo Sison (Page Author)

An honors graduate of the University of Florida, Dr. Sison started his pharmacy career in a community setting, extending his services to hospitals and clinics over time. He has also worked in medication therapy management, advising patients on proper medication use for their chronic health conditions. Read More....