What is mechanism of action?

mechanism of action is Thyroid Hormone Synthesis Inhibitors [MoA]

Methimazole

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Methimazole Prescribing Information

Methimazole is administered orally. The total daily dosage is usually given in 3 divided doses at approximately 8-hour intervals.

Adults-

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 maintenance dosage is 5 mg to 15 mg daily.

Pediatric -

Initially, the daily dosage is 0.4 mg/kg of body weight divided into 3 doses and given at 8-hour intervals. The maintenance dosage is approximately 1/2 of the initial dose.

Major adverse reactions (which occur with much less frequency than the minor adverse reactions) include inhibition of myelopoieses (agranulocytosis, granulocytopenia, thrombocytopenia, and aplastic anemia), drug fever, a lupus-like syndrome, insulin autoimmune syndrome (which can result in hypoglycemic coma), hepatitis (jaundice may persist for several weeks after discontinuation of the drug), periarteritis, and hypoprothrombinemia. Nephritis occurs very rarely. There have been postmarketing case reports of acute pancreatitis.

There are reports of a vasculitis, often associated with the presence of anti-neutrophilic cytoplasmic antibodies (ANCA), resulting in severe complications (see WARNINGS).

Minor adverse reactions include skin rash, urticaria, nausea, vomiting, epigastric distress, arthralgia, paresthesia, loss of taste, abnormal loss of hair, myalgia, headache, pruritus, drowsiness, neuritis, edema, vertigo, skin pigmentation, jaundice, sialadenopathy, and lymphadenopathy.

To report

SUSPECTED ADVERSE REACTIONS

, contact Macleods Pharma USA, Inc. at 1-888-943-3210 or 1-855-926-3384 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Anticoagulants (oral)

- Due to potential inhibition of vitamin K activity by methimazole, the activity of oral anticoagulants (e.g., warfarin) may be increased; additional monitoring of PT/INR should be considered, especially before surgical procedures.

β-adrenergic blocking agents

- Hyperthyroidism may cause an increased clearance of beta blockers with a high extraction ratio. A dose reduction of beta-adrenergic blockers may be needed when a hyperthyroid patient becomes euthyroid.

Digitalis glycosides

- Serum digitalis levels may be increased when hyperthyroid patients on a stable digitalis glycoside regimen become euthyroid; a reduced dosage of digitalis glycosides may be needed.

Theophylline

- Theophylline clearance may decrease when hyperthyroid patients on a stable theophylline regimen become euthyroid; a reduced dose of theophylline may be needed.

Methimazole (1-methylimidazole-2-thiol) is a white, crystalline substance that is freely soluble in water. It differs chemically from the drugs of the thiouracil series primarily because it has a 5-instead of a 6-membered ring.

Methimazole tablet, USP contains 5 mg or 10 mg (43.8 or 87.6 μmol) methimazole, an orally administered antithyroid drug.

Each tablet also contains lactose monohydrate, pregelatinised starch, talc, and magnesium stearate.

The molecular weight is 114.17, and the molecular formula is C₄H₆N₂S.The structural formula is as follows:

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Methimazole

Methimazole Prescribing Information

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