Question

Which hyperthyroid drug is safer during the first trimester of pregnancy?

• A. Propylthiouracil
• B. Methimazole
• C. Carbimazole
• D. Radioactive iodine

Hint:

In the first trimester, Propylthiouracil (PTU) is preferred over methimazole or carbimazole due to its lower risk of birth defects.

Answer 1

The Correct Option is A

Propylthiouracil: This is the safest option for treating hyperthyroidism during the first trimester of pregnancy. Propylthiouracil (PTU) is preferred in early pregnancy because it has a lower risk of teratogenicity compared to other thyroid drugs. It inhibits the production of thyroid hormones and does not cross the placenta as easily.
Methimazole: While methimazole is effective for treating hyperthyroidism, it is not recommended in the first trimester because it is associated with an increased risk of birth defects, particularly congenital malformations. It can be used later in pregnancy.
Carbimazole: This drug is a prodrug of methimazole and has the same risks. It should be avoided in the first trimester for the same reasons as methimazole.
Radioactive iodine: This is contraindicated during pregnancy as it can cause permanent thyroid damage to the fetus, leading to hypothyroidism. Thus, the correct answer is Propylthiouracil (1), as it is safer during the first trimester of pregnancy.