During either carbimazole or propylthiouracil treatment, advise patients to report signs and symptoms of infection, especially sore throat, which may indicate bone marrow suppression, and to discontinue medication pending further investigation. The drug should only be recommenced once neutropenia has been excluded following a blood count. Routine monitoring of white blood cell count is unnecessary. If sensitivity (eg rash) occurs with carbimazole then propylthiouracil is an alternative. Propylthiouracil is the drug of choice in pregnant women. For information on the treatment of thyrotoxic crisis, refer to BNF.

CARBIMAZOLE - (First line)

Important: Therapy notes

MHRA alert: Carbimazole: risk of acute pancreatitis (February 2019) (www.gov.uk).
MHRA alert: Carbimazole: increased risk of congenital malformations; strengthened advice on contraception (February 2019 (www.gov.uk).

Risk minimisation materials

Important: Formulation and dosage details

Formulation:

Tablets 5mg, 20mg (specialist use only)

Dosage:

Initially 20 to 40mg once daily. Repeat TFTs after 4 to 6 weeks and adjust the dose following specialist advice.

PROPYLTHIOURACIL - (Second line)

Important: Therapy notes

Important: Formulation and dosage details

Formulation:

Tablets 50mg (s)

Dosage:

Initially 200mg daily in divided doses. Repeat TFTs after 4 to 6 weeks and adjust the dose following specialist advice.

PROPRANOLOL

Important: Therapy notes

MHRA advice: Drug-name confusion: reminder to be vigilant for potential errors (January 2018) (www.gov.uk).

Important: Formulation and dosage details

Formulation:

Modified release capsules 80mg, 160mg

Dosage:

By mouth, for the relief of thyrotoxic symptoms modified release capsules 80 to 160mg daily.

AQUEOUS IODINE ORAL SOLUTION

Important: Formulation and dosage details

Formulation:

Solution total iodine (Lugol’s Solution) 130mg/mL (s) unlicensed

Editorial Information

Document Id: F198