Methimazole Dosage

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Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Hyperthyroidism

Initial:
Mild hyperthyroidism: 5 mg orally every 8 hours.
Moderately severe hyperthyroidism: 10 mg orally every 8 hours (up to 40 mg per day).
Severe hyperthyroidism: 20 mg orally every 8 hours.

Maintenance:
5 to 15 mg orally daily.

Usual Pediatric Dose for Hyperthyroidism

Greater than or equal to 1 year:

Initial dose: 0.4 mg/kg/day orally in 3 equally divided doses 8 hours apart.

Maintenance dose: 0.2 mg/kg/day orally in 3 equally divided doses 8 hours apart.

Maximum dose: 30 mg/day.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

An elevated TSH, during periodic monitoring of thyroid function, should lead to a decrease in the dosage of methimazole.

Precautions

Because methimazole may cause hypoprothrombinemia and bleeding, prothrombin time should be evaluated during therapy, especially before surgical procedures.

Periodic monitoring of thyroid function is necessary, and the finding of an elevated TSH warrants a decrease in dose.

Dialysis

Not dialyzable.

Other Comments

Methimazole has been given as a once daily dose in the morning.

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