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Drug Interactions due to Chelating Cations

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Drug Interactions due to Chelating Cations, Chelating Cation, Cation Binding

  • Definitions
  1. Charged elements that bind drugs in the intestinal tract and prevent absorption
  • Mechanism
  1. Multivalent cations bind medications and form insoluble complexes that cannot be absorbed across gut
  • Causes
  • Cations
  1. Aluminum (e.g. amphojel)
  2. Magnesium (e.g. Magnesium Oxide, Magnesium Citrate)
  3. Aluminum-Magnesium Combinations (e.g. Maalox)
  4. Calcium (e.g. Tums)
  5. Iron (e.g. iron supplements)
  • Drug Interactions
  • Decreased Absorption when Cations present
  1. Tetracyclines
  2. Fluoroquinolones
  3. Thyroid medications (e.g. Synthroid)
  • Management
  1. Administer medications 2 hours before or 6 hours after cation containing agents
  • References
  1. Carpenter (2019) Am Fam Physician 99(9): 558-64 [PubMed]