Which drug should be avoided by women of childbearing potential due to potential fetal harm?

• A. Methotrexate
• B. Finasteride
• C. Fluoxetine
• D. Sulfasalazine

Answer: (B)

Teratogenic risk is the issue here: some medicines can cause birth defects when a woman could become pregnant. Finasteride is a 5-alpha-reductase inhibitor that blocks the conversion of testosterone to dihydrotestosterone, which is essential for the development of male genitalia in the fetus. Because of this, exposure during pregnancy—especially in the first trimester—can cause abnormalities in the external genitalia of a male fetus. For this reason, women of childbearing potential should avoid handling finasteride tablets (even if intact) and should not become pregnant while taking it; alternative therapies should be used. Other drugs on the list have pregnancy risks as well, but finasteride is the one most clearly and specifically associated with fetal genital abnormalities in a male fetus, making it the drug to avoid.