Hyperthyroidism

Treatment of hyperthyroidism with antithyroid drugs
Carbimazole
Carbimazole 5mg tablets

To be initiated on specialist advice. 15-40mg daily until euthyroid (usually 4-8 weeks), then progressively reduced to a maintenance dose, typically 5-15mg, daily usually for 18 months.

Carbimazole 10mg tablets

To be initiated on specialist advice. 15-40mg daily until euthyroid (usually 4-8 weeks), then progressively reduced to a maintenance dose, typically 5-15mg, daily usually for 18 months.

Carbimazole 15mg tablets

To be initiated on specialist advice. 15-40mg daily until euthyroid (usually 4-8 weeks), then progressively reduced to a maintenance dose, typically 5-15mg, daily usually for 18 months.

Carbimazole 20mg tablets

To be initiated on specialist advice. 15-40mg daily until euthyroid (usually 4-8 weeks), then progressively reduced to a maintenance dose, typically 5-15mg, daily usually for 18 months.

Propylthiouracil may be an alternative in early pregnancy or for patients who suffer sensitivity reactions to carbimazole.

Propylthiouracil
Propylthiouracil 50mg tablets

To be initiated on specialist advice. 200-400mg daily, maintained until patient is euthyroid, and the dose can be gradually reduced to a maintenance dose of 50-150mg daily.

Prescribing Notes:

  • Carbimazole 40-60mg daily may be given with levothyroxine 100-125micrograms daily in a block and replace regimen, usually for 18 months.
  • Carbimazole has rarely been associated with bone marrow suppression and treatment should be stopped promptly if there is clinical or laboratory evidence of neutropenia. Patients should be asked to report symptoms and signs suggestive of infection, especially sore throat, fever or mouth ulcers. A white blood cell count should be performed if there is any clinical evidence of infection. If there is clinical or laboratory evidence of neutropenia, carbimazole or propylthiouracil should be stopped.
  • Pregnant patients receiving anti-thyroid drugs must be monitored in secondary care.
  • MHRA/ CHM (Feb 19) “Carbimazole is associated with an increased risk of congenital malformations when used during pregnancy, especially in the first trimester and at high doses (daily dose of 15 mg or more). Women of childbearing potential should use effective contraception during treatment with carbimazole. It should only be considered in pregnancy after a thorough benefit-risk assessment, and at the lowest effective dose without additional administration of thyroid hormones—close maternal, fetal, and neonatal monitoring is recommended.”

History Notes

16/02/2022

East Region Formulary content agreed.

Treatment of hyperthyroidism with beta blockers
Propranolol
Propranolol 10mg tablets

Thyrotoxicosis (adjunct), 10-40mg 3-4 times daily.

Propranolol 40mg tablets

Thyrotoxicosis (adjunct), 10-40mg 3-4 times daily.

Prescribing Notes:

  • Propranolol can be withdrawn once hyperthyroidism is controlled (2-6 weeks), and the patient maintained on carbimazole.

History Notes

16/02/2022

East Region Formulary content agreed.

Hyperthyroid crisis
Potassium iodide
Potassium iodide 65mg tablets

As per specialist.

History Notes

16/02/2022

East Region Formulary content agreed.

Treatment of hyperthyroidism with antithyroid drugs
Carbimazole
Carbimazole 5mg tablets

For dose, refer to BNF for Children and follow specialist advice.

Carbimazole 10mg tablets

For dose, refer to BNF for Children and follow specialist advice.

Carbimazole 15mg tablets

For dose, refer to BNF for Children and follow specialist advice.

Carbimazole 20mg tablets

For dose, refer to BNF for Children and follow specialist advice.

Propylthiouracil may be an alternative in early pregnancy or for patients who suffer sensitivity reactions to carbimazole.

Propylthiouracil
Propylthiouracil 50mg tablets

For dose, refer to BNF for Children and follow specialist advice.

Prescribing Notes:

  • Carbimazole may be given with levothyroxine in a block and replace regimen, usually for 18 months.
  • See the link for the medicines for children leaflet: carbimazole for hyperthyroidism.
  • Carbimazole and propylthiouracil have been associated with bone marrow suppression and treatment should be stopped promptly if there is clinical or laboratory evidence of neutropenia. Patients/carers should be asked to report symptoms and signs suggestive of infection, especially sore throat, fever or mouth ulcers. A white blood cell count should be performed if there is any clinical evidence of infection. If there is clinical or laboratory evidence of neutropenia, carbimazole or propylthiouracil should be stopped.
  • Pregnant patients receiving anti-thyroid drugs must be monitored in secondary care.
  • MHRA Drug Safety Update (Feb 19) “Carbimazole is associated with an increased risk of congenital malformations when used during pregnancy, especially in the first trimester and at high doses (daily dose of 15mg or more). Women of childbearing potential should use effective contraception during treatment with carbimazole. It should only be considered in pregnancy after a thorough benefit-risk assessment, and at the lowest effective dose without additional administration of thyroid hormones – close maternal, fetal and neonatal monitoring is recommended.”
  • Refer to guidance in Scottish Paediatric Endocrine Group and British Society for Paediatric Endocrinology and Diabetes.

History Notes

29/02/2024

East Region Formulary content agreed.

Treatment of hyperthyroidism with beta blockers

Consider starting treatment at lower doses and increasing gradually, for example starting propranolol 10mg twice daily.
Prescribers should be aware of recent increases in propranolol overdoses and consider patients risk factors before prescribing.

Propranolol
Propranolol 10mg tablets

For dose, refer to BNF for Children and follow specialist advice.

Propranolol 40mg tablets

For dose, refer to BNF for Children and follow specialist advice.

Propranolol 5mg/5ml oral solution sugar free

For dose, refer to BNF for Children and follow specialist advice.

Prescribing Notes:

History Notes

29/02/2024

East Region Formulary content agreed.

Hyperthyroid crisis
Potassium iodide
Potassium iodide 65mg tablets

As per specialist.

History Notes

29/02/2024

East Region Formulary content agreed.