From the Guidelines
No, propylthiouracil (PTU) and carbimazole should not be combined for treating hyperthyroidism. These medications belong to the same class of drugs called thionamides or antithyroid drugs, and they work through the same mechanism by inhibiting thyroid hormone production. Using them together would increase the risk of side effects without providing additional therapeutic benefit, which could negatively impact morbidity, mortality, and quality of life 1.
Treatment Approach
Instead, either medication should be used alone at appropriate doses. For initial treatment of hyperthyroidism, typical starting doses are carbimazole 10-40 mg daily or PTU 100-300 mg daily in divided doses, with the dose adjusted based on thyroid function tests every 4-6 weeks until euthyroidism is achieved. Both medications can cause similar side effects including rash, joint pain, and rarely agranulocytosis (dangerous decrease in white blood cells) 1.
Considerations for Use
The choice between carbimazole and PTU should be based on individual factors such as pregnancy status (PTU is preferred in the first trimester due to possible teratogenicity associated with methimazole), side effect profile, and availability 1. If one medication is not effective or causes side effects, switching to the other may be considered, but they should never be used simultaneously. It's also important to monitor for side effects such as agranulocytosis, hepatitis, vasculitis, and thrombocytopenia, and to adjust treatment accordingly to minimize risks and optimize outcomes in terms of morbidity, mortality, and quality of life.
From the Research
Combination Therapy for Hyperthyroidism
- The use of Propylthiouracil (PTU) in combination with Carbimazole for treating hyperthyroidism is not directly addressed in the provided studies.
- However, the studies discuss the adverse effects and efficacy of PTU and Carbimazole (or its active metabolite Methimazole) as individual treatments for hyperthyroidism 2, 3, 4, 5, 6.
- According to the studies, PTU and Methimazole/Carbimazole have different side effect profiles, with PTU being associated with a higher risk of liver injury 3, 5.
- The studies suggest that the choice of antithyroid drug should be based on the individual patient's needs and risk factors, such as pregnancy or liver disease 3, 5.
Adverse Effects of Antithyroid Drugs
- The studies report that antithyroid drugs, including PTU and Methimazole/Carbimazole, can cause adverse effects such as hypothyroidism, rash, pruritus, neutropenia, and liver injury 2, 3, 4, 5, 6.
- The incidence of these adverse effects can vary depending on the specific drug, dose, and patient population 3, 5.
- The studies emphasize the importance of monitoring patients for adverse effects and adjusting treatment accordingly 2, 3, 4, 5, 6.
Treatment Considerations
- The studies discuss the use of PTU and Methimazole/Carbimazole in different patient populations, including pregnant women, children, and adults 3, 5, 6.
- The choice of antithyroid drug may depend on the patient's age, pregnancy status, and other individual factors 3, 5.
- The studies suggest that radioactive iodine therapy may be considered as an alternative treatment option for some patients with hyperthyroidism 6.