Methimazole

Also known as: Thiamazole, Methylmercaptoimidazole

Drug #461

Methimazole is antithyroid drug that is employed for the preparation of the hyperthyroid patient for surgery and for the total treatment of hyperthyroidism. Methimazole is the active metabolite of carbimazole and is given by mouth. Chemically Methimazole is 1, 3-dihydro-1-methyl-2H-imidazole-2-thione.

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Primary Characteristics

Methimazole is also known as Thiamazole, Methylmercaptoimidazole.

It is of Natural origin and belongs to Imidazole.

It belongs to Thyroid peroxidease inhibitor pharmacological group on the basis of mechanism of action and also classified in Antithyroid pharmacological group.

Molecular Weight: 114.2 · Solubility in Water: 1 in 5 · Solubility in Alcohol: 1 in 5 · Non-proprietary name: Methimazole.

Pharmacokinetics

Absorption: Methimazole has an oral bioavailability is 95% (±5%).

Distribution: Methimazole has a volume of distribution is 0.5 l/kg. plasma protein binding is 40%.

Elimination: it is metabolised via Hepatic, Thyroid, plasma half-life is 3-5 hr, renal excretion is 12%.

Indications

Methimazole is primarily indicated in conditions like Hyperthyroidism, Hyperthyroidism of graves disease, Thyrotoxicosis.

Contraindications

Methimazole is contraindicated in conditions like Bone marrow depression, Agranulocytosis, Destructive hyperthyroidism.

Dosage

Methimazole's dosage details are as follows:

Dose	Single Dose	Frequency	Route	Instructions
Adult Dosage
35 mg	35 mg	—		Modevately severe.
60 mg	60 mg	—		severe hyperthroidism
10 mg	10 mg	Every 8h	PO	Maintance
15 mg/kg	15 mg/kg	Every 24h	PO	Initial child hyperthyroidino,
Paediatric Dosage (20kg)
No data.
Neonatal Dosage (3kg)
No data.

Drug Interactions

1 interaction

Major1 interaction

Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.

Side Effects

Methimazole in overdosage may give rise to further complications which include Drug fever , Lupus like syndrome , Hypoprothorombinemia, Aplastic anemia , Vasculitis , Hypothyroidism , Hepatitis .

Methimazole produces potentially life-threatening effects which include Agranulocytosis. Careful monitoring is needed with proper medical management.

Methimazole is known to cause more or less tolerable side effects which are usually transient. These include Arthralgia, Drowsiness, Edema, Hair loss, Headache, Loss of taste, Nausea, Skin rash.

Warnings / Precautions

Excessive dose of antithyroid should not be used, because it may cause hypothyroidism or goiter. Treatment with methimazole should be discontinued immediately if there is any clinical or lab. evidence of neutropenia. It is not recommended to use high dose during pregnancy or lactation. Before having an emergency treatment or surgery including dental surgery, tell the doctor about the use of the drug.

Available Brands

None recorded.

Storage Conditions

Methimazole should be stored Tab.

Drug Classification

1.18.8 — Thyroid & antithyroid preparations