Indications: hyperthyroidism, thyrotoxicosis.

Cautions: pregnancy, breast-feeding; tracheal obstruction; large goiter; liver disorders. Doctors should instruct patients about important symptoms and signs of bone marrow suppression induced by carbimazole and the need to stop treatment promptly and do the following:

Patient to report symptoms and signs suggestive of infection, especially sore throat immediately.

To perform white blood cell count if there is any clinical evidence of infection. Stop Carbimazole immediately if there is clinical or laboratory evidence of neutropenia.

Dose: 15 to 40 mg daily; a larger dose may be required occasionally. This dose is continued until the patient becomes euthyroid, usually after 4 to 8 weeks and the dose is then gradually reduced to a maintenance dose of 5 to 15 mg. Duration of therapy is given for 12 to 18 months. Children to be treated by specialist with initial dose of carbimazole of 250 mcg/kg three times daily, and to be adjusted according to response.

Side Effects: Nausea, mild gastro-intestinal disturbances, headache, rashes and pruritus, arthralgia; rarely myopathy, alopecia, bone marrow suppression (including pancytopenia and agranulocytosis), jaundice.

Breast feeding: The lowest effective dose of the drug should be used as the amount in milk may be sufficient to affect neonatal thyroid function. Carbimazole appears in breast milk but this does not preclude breast-feeding: as long as neonatal development is closely monitored and the lowest effective dose is used.