Carbimazole

Question 1

Carbimazole?

Answer 1

• Carbimazole is used in the management of thyrotoxicosis.
• It is typically given in high doses for 6 weeks until the patient becomes euthyroid before being reduced.

Question 2

Carbimazole: Mechanism of action?

Answer 2

• blocks thyroid peroxidase from coupling and iodinating the tyrosine residues on thyroglobulin → reducing thyroid hormone production
• in contrast propylthiouracil as well as this central mechanism of action also has a peripheral action by inhibiting 5’-deiodinase which reduces peripheral conversion of T4 to T3

Question 3

Carbimazole: Adverse Effects?

Answer 3

Adverse effects:

• agranulocytosis
• crosses the placenta, but may be used in low doses
• during pregnancy