• Special considerations
  • Oral tetracyclines should not be taken with substances that contain large amounts of Ca²⁺, Mg2+, or Fe2+ (e.g., milk, antacids, iron supplements, respectively) because divalent cations inhibit the intestinal absorption of tetracyclines.
    • Tetracyclines interact with polyvalent cations to form nonabsorbable chelate complexes
  • CNS penetration is limited