Carbimazole

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Carbimazole
Systematic (IUPAC) name
ethyl 3-methyl-2-sulfanylidene-imidazole-1-carboxylate
Identifiers
CAS number	22232-54-8
ATC code	H03BB01
PubChem	31072
DrugBank	APRD00503
Chemical data
Formula	C7H10N2O2S
Mol. weight	186.233 g/mol
Pharmacokinetic data
Bioavailability	?
Protein binding	85%
Metabolism	?
Half life	?
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status	℞ Prescription only
Routes	oral

Carbimazole is used to treat hyperthyroidism. It prevents the peroxidase enzyme from coupling and iodinating the tyrosine residues on thyroglobulin, hence reducing the T3/T4.

[edit] Clinical use

Therapy for hyperthyroidism generally starts at a high dose of 15 - 40mg continued until the patient has normal thyroid function, and then reduced to a maintenance dose of 5 - 15mg. Treatment is usually given for 12 - 18 months followed by a trial withdraw. Whilst rashes and pruritis are common, these can often be treated with antihistamines without stopping the carbimazole. For those patients where sensitivity reactions can not be controlled, propylthiouracil may be used as an alternative.

Its most serious rare side effect is bone marrow suppression causing neutropenia and agranulocytosis. This may occur at any stage during treatment and without warning. Patients are advised to immediately report symptoms of infection, especially sore throats, so that a full blood count test may be arranged. If this confirms a low neutrophil count then the drug must be discontinued immediately, allowing for usually a prompt recovery. However failure to report suggestive symptoms or delays in considering the possibility of immunosuppresion and its testing, can lead to fatalities.

[edit] See also

• propylthiouracil

[edit] References

• British National Formulary 45 March 2003