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, with subsequent adjustments based on thyroid function tests. For severe hyperthyroidism, initial doses of 30-40 mg daily may be used, but rarely would doses exceed 40-60 mg daily due to increased risk of side effects. After achieving euthyroidism (normal thyroid function), maintenance doses are typically reduced to 5-15 mg daily. Methimazole works by inhibiting thyroid peroxidase, which prevents the synthesis of thyroid hormones. Higher doses carry increased risks of adverse effects including rash, gastrointestinal symptoms, agranulocytosis, and hepatotoxicity. Regular monitoring of complete blood counts and liver function is essential, especially at higher doses. Patients should be instructed to report symptoms like fever, sore throat, unusual bleeding or bruising, which could indicate serious adverse effects requiring immediate medical attention.
Key points to consider:
- Initial doses: 10-30 mg daily
- Severe hyperthyroidism: 30-40 mg daily
- Maximum dose: 60 mg daily
- Maintenance dose: 5-15 mg daily
- Monitoring: complete blood counts and liver function
Note: The provided evidence does not directly address the question, but based on general medical knowledge, the above answer is provided, citing no specific reference as none of the provided references directly answer the question about methimazole dosage.
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.