From the Guidelines
The maximum dose of methimazole is typically 60 mg per day, though most patients require much lower doses. Treatment usually begins with 10-30 mg daily, divided into multiple doses for severe hyperthyroidism, with subsequent dose adjustments based on thyroid function tests. After achieving euthyroidism (normal thyroid function), maintenance doses of 5-15 mg daily are common. Methimazole works by inhibiting thyroid peroxidase, which reduces thyroid hormone production. Patients should be monitored for side effects, which can include rash, joint pain, and rarely agranulocytosis (dangerous decrease in white blood cells). Complete blood counts should be obtained if fever, sore throat, or other signs of infection develop. Methimazole is preferred over propylthiouracil (PTU) in most cases due to its longer duration of action, allowing once-daily dosing, and lower risk of severe liver injury. Pregnant women in their first trimester are an exception, as PTU is generally preferred during this period due to the potential risk of methimazole-associated birth defects.
Key points to consider:
- Initial treatment doses: 10-30 mg daily
- Maintenance doses: 5-15 mg daily
- Maximum dose: 60 mg per day
- Monitoring for side effects: rash, joint pain, agranulocytosis
- Preference over PTU: longer duration of action, lower risk of severe liver injury
- Exception for pregnant women in their first trimester: PTU preferred due to potential risk of methimazole-associated birth defects.
Note: The provided evidence does not directly address the question about methimazole, but based on general medical knowledge and the example answer provided, the above response is given.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Methimazole tablets, USP are administered orally. The total daily dosage is usually given in 3 divided doses at approximately 8-hour intervals. Adult The initial daily dosage is 15 mg for mild hyperthyroidism, 30 mg to 40 mg for moderately severe hyperthyroidism and 60 mg for severe hyperthyroidism, divided into 3 doses at 8-hour intervals. The maximum dose of Methimazole (MMI) is 60 mg per day, as indicated for severe hyperthyroidism 1.
From the Research
Maximum Dose of Methimazole (MMI)
- The maximum dose of Methimazole (MMI) is not explicitly stated in the provided studies, but the highest dose mentioned is 60 mg/day 2 and 30 mg/day 3.
- In one study, MMI was used at an initial dose of 30 mg/day for severe Graves' disease (GD) hyperthyroidism 3.
- Another study used MMI at a dose of 10 to 60 mg/day, which was gradually tapered 2.
- A study comparing the efficacy of a single daily dose of MMI and propylthiouracil (PTU) used a dose of 15 mg MMI once daily 4.
- A prospective long-term follow-up study used conventional divided doses of 10 mg 3 times daily and a small single daily dose of 15 mg once daily of MMI 5.