A pregnant woman in her second trimester requires treatment for scrub typhus. Why are tetracyclines avoided during pregnancy?
- A They cross the placenta and deposit in fetal bones and teeth, and inhibit skeletal growth ✓
- B They cause fetal hemolysis through glutathione depletion
- C They induce fetal hepatic microsomal enzymes causing kernicterus
- D They produce fetal cardiac conduction defects via potassium channel blockade
Correct answer: A. They cross the placenta and deposit in fetal bones and teeth, and inhibit skeletal growth
Explanation
Tetracyclines chelate calcium and deposit in developing bone and dentition. Fetal exposure causes tooth discoloration and enamel hypoplasia, and they suppress fetal skeletal growth by their antianabolic effect on protein synthesis, so they are contraindicated in pregnancy and in children below eight years. Hemolysis is associated with sulfonamides and oxidant drugs, kernicterus with sulfonamide displacement of bilirubin, and cardiac conduction defects with macrolide QT prolongation, none of which applies here.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.