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