Methimazole Pharmacology


About Methimazole
Thioureylene antithyroid agent, thyroid peroxidase inhibitor.
Mechanism of Action of Methimazole
Methimazole binds to thyroid peroxidase and thereby inhibits the conversion of iodide to iodine. Thyroid peroxidase normally converts iodide to iodine (via hydrogen peroxide as a cofactor) and also catalyzes the incorporation of the resulting iodide molecule onto both the 3 and/or 5 positions of the phenol rings of tyrosines found in thyroglobulin. Thyroglobulin is degraded to produce thyroxine (T4) and tri-iodothyronine (T3), which are the main hormones produced by the thyroid gland. So methimazole effectively inhibits the production of new thyroid hormones.
Pharmacokinets of Methimazole
Absorption:Rapid with an oral bioavailability of 93%
Metabolism:Primarily hepatic. Metabolized rapidly, requiring frequent administration
Onset of Action for Methimazole
Duration of Action for Methimazole
Half Life of Methimazole
5-6 hours
Side Effects of Methimazole
3.Skin pigmentation
5.Rare:Agranulocytosis,Aplastic anemia,Hepatotoxicity
Contra-indications of Methimazole
Hypersensitivity to methimazole
Special Precautions while taking Methimazole
1.Liver disease
2.Risk of rare but serious agranulocytosis, cholestastic jaundice & rare congenital abnormalities (Propylthiouracil preferred in pregnancy)
3.Discontinue if agranulocytosis, pancytopenia, hepatitis, fever, or exfoliative dermatitis occur
4.Patients who receive methimazole should be under close surveillance and should be cautioned to report immediately any evidence of illness, particularly sore throat, skin eruptions, fever, headache, or general malaise. In such cases, white-blood cell and differential counts should be made to determine whether agranulocytosis has developed.
5.Particular care should be exercised with patients who are receiving additional drugs know to cause agranulocytosis.
6.High relapse rate (more likely in smokers)
Pregnancy Related Information
Old Age Related Information
Breast Feeding Related Information
Children Related Information
Indications for Methimazole
For the treatment of hyperthyroidism, goiter, Graves disease and psoriasis.
Interactions for Methimazole
Warfarin (Coumadin) works by reducing the activity of vitamin K and therefore the formation of vitamin K dependent clotting factors. Methimazole may increase the activity of warfarin by further reducing the activity of vitamin K in the body.
Typical Dosage for Methimazole

Adult: The initial daily dosage is 15 mg. It may be increased upto 60 mg, divided into 3 doses at 8-hour intervals. The maintenance dosage is 5 to 15 mg daily.

Pediatric: Initially, the daily dosage is 0.4 mg/kg, divided into 3 doses and given at 8-hour intervals.

Thyrotoxic Crisis:

20-30 mg 6-12hr for short-term, then reduce dose to maintenance dose (5-15 mg/day)

Schedule of Methimazole
Storage Requirements for Methimazole
Store it at controlled room temperature (15? to 30?C), and in an airtight container. Keep away from children.

Effects of Missed Dosage of Methimazole
Effects of Overdose of Methimazole

Home Delivery for Methimazole in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including methimazole.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for methimazole and other medicines and health products. Home delivery services for methimazole may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take methimazole only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for methimazole before they complete the sale. You can get this information while placing the order for methimazole with the pharmacy.

Methimazole is a generic medicine name and there are several brands available for it. Some of the brands for methimazole might be better known than methimazole itself. If the pharmacy that's willing to deliver medicines to your home doesn't have methimazole in stock, you can ask for one of the branded alternatives for methimazole.