Carbimazole is an anti-thyroid agent, once converted to its active form of methimazole, it prevents the thyroid peroxidase enzyme from coupling and iodinating the tyrosine residues on thyroglobulin, hence reducing the production of the thyroid hormones T3 and T4.
After oral ingestion, peak plasma concentrations of thiamazole, the active moiety, occur at 1 to 2 hours. The total volume of distribution of thiamazole is 0.5 1/kg. Carbimazole has a half-life of 5.3 to 5.4 hours. Over 90% of orally administered carbimazole is excreted in the urine as thiamazole or its metabolites. The remainder appears in faeces. There is 10% enterohepatic circulation.
The usual starting dose for adults is between 20mg and 60mg a day, split into 2 or 3 smaller doses. Final dosage is usually in the range of 5-15mg per day which may be taken as single daily dose. Therapy should be continued for at least six months and upto 18 months with thyroid function test and approximate dose modification.
HDP pot of 100 tablets