Drug Interactions Newsletter

Volume 2, Issue 18, 05/04/2010

Question

How does aluminum hydroxide chelate with and reduce the intestinal absorption of the fluoroquinolone antibiotic, levofloxacin (Levaquin)?

Answer

Aluminum hydroxide Al(OH)₃ is a common ingredient in many over-the-counter (OTC) oral antacid medications.   It is also used in the short-term as an oral phosphate binder in patients with hyperphosphatemia secondary to chronic kidney disease.    When using aluminum based products as an antacid, the short duration of action requires frequent administration throughout the day.  Due to its availability OTC, the route, the frequency of administration throughout the day, and the recognition that many people prefer to take all of their medications at the same time, it is plausible that the introduction of levofloxacin (Levaquin) for the treatment of a bacterial infection could be met with the presence of a di- or tri-valent cation, such as aluminum.  The coadministration of levofloxacin and aluminum hydroxide can result in a reduction in the overall absorption and bioavailability of levofloxacin thus increasing the risk of the patient either developing bacterial drug resistance and/or treatment failure.¹ 

How does aluminum specifically interact with levofloxacin to cause a reduction in absorption or bioavailability?
A basic evaluation of the chemical structure of levofloxacin reveals that each levofloxacin molecule has...

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