A 45-year-old woman on long-term tetracycline for acne develops yellow-brown discoloration of permanent teeth in her 8-year-old child who was inadvertently exposed. This occurs because tetracycline:

• A Inhibits type I collagen synthesis in developing dentin
• B Competitively inhibits fluoride uptake in enamel hydroxyapatite
• C Chelates calcium ions and incorporates into calcifying tissues ✓
• D Activates osteoclasts causing localized dental resorption

Explanation

Tetracyclines have a high affinity for divalent cations and chelate calcium, forming tetracycline-calcium orthophosphate complexes that are permanently deposited in forming bones and teeth. When deposited in developing teeth (up to 8 years of age), this causes yellow-gray-brown discoloration and enamel hypoplasia under UV exposure. Therefore tetracyclines are contraindicated in children under 8 years and in pregnant or lactating women.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.