II. Definitions
- Charged elements that bind drugs in the intestinal tract and prevent absorption
III. Mechanism
- Multivalent cations bind medications and form insoluble complexes that cannot be absorbed across gut
IV. 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)
V. Drug Interactions: Decreased Absorption when Cations present
- Tetracyclines
- Fluoroquinolones
- Thyroid medications (e.g. Synthroid)
VI. Management
- Administer medications 2 hours before or 6 hours after cation containing agents