Metothyrin (Thiamazole)

Thiamazole blocks the enzyme thyroid peroxidase, which is essential for iodination of tyrosine residues and the coupling reactions that produce T3 and T4 hormones. By inhibiting these steps, the drug reduces the synthesis of thyroid hormones, lowering their circulating concentrations.

The dose of Metothyrin is individualized. A qualified prescriber determines the appropriate amount based on the patient’s thyroid function tests, severity of disease, age, weight and co‑existing conditions. Dosage adjustments are made during treatment to maintain target hormone levels.

Thiamazole is classified as Pregnancy Category D, indicating evidence of risk to the fetus. It should be avoided during pregnancy unless the potential benefit justifies the risk. Limited data are available for breastfeeding; the drug may pass into milk, so a risk‑benefit assessment is required.

To order Metothyrin, submit an enquiry on the product page at gnhindia.com, specifying the required quantity. GNH India supplies hospitals, pharmacies and procurement teams worldwide, verifies trade or institutional credentials, and then provides pricing, availability, shipping details and any necessary import documentation.

The primary alternative to thiamazole is propylthiouracil (PTU). Both are thionamides that inhibit thyroid hormone synthesis, but PTU also blocks peripheral conversion of T4 to T3. Thiamazole generally has a longer half‑life, allowing once‑daily dosing, whereas PTU may be preferred in the first trimester of pregnancy due to a different safety profile.

Metothyrin tablets should be stored at room temperature, below 25 °C, in the original container to protect them from moisture and light. Keep the product out of reach of children and avoid storing in humid environments such as bathrooms.

Metothyrin is taken orally as a tablet. Patients should swallow the tablet whole with a glass of water, preferably on an empty stomach, unless instructed otherwise by their healthcare provider. Doses are usually taken once daily, but the prescriber may adjust frequency based on clinical response.

The most serious adverse events include agranulocytosis (a marked drop in white blood cells), severe liver injury, and rare hypersensitivity reactions such as Stevens‑Johnson syndrome. Patients should seek immediate medical attention for fever, sore throat, jaundice, dark urine, or skin rash.

Metothyrin is contraindicated in patients with known hypersensitivity to thiamazole or other thionamides, in those with severe liver disease, and in pregnant women unless the therapeutic benefit outweighs the fetal risk. Caution is also advised for individuals with pre‑existing blood dyscrasias.