Tetracyclines are contraindicated in children under 8 years primarily because they:

• A Cause irreversible eighth nerve damage
• B Chelate calcium in developing bones and teeth, causing permanent discoloration, enamel hypoplasia, and impaired bone growth ✓
• C Inhibit dihydroorotate dehydrogenase causing mitochondrial toxicity in rapidly dividing cells
• D Cause gray baby syndrome due to immature glucuronidation

Explanation

Tetracyclines form stable chelation complexes with divalent cations (Ca2+, Mg2+, Fe2+). In children under 8, this chelation occurs in the hydroxyapatite matrix of developing teeth and bone. In teeth, the tetracycline-calcium orthophosphate complex causes permanent yellow-brown-gray staining that fluoresces under UV light; enamel hypoplasia also occurs as tetracyclines impair ameloblast function. Gray baby syndrome is caused by chloramphenicol due to immature hepatic glucuronidation. Eighth nerve damage is characteristic of aminoglycosides.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.