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Norfloxacin interaction with antacids and minerals
N R Campbell1, M Kara, B B Hasinoff
1Faculty of Medicine, Memorial University of Newfoundland, St John's, Canada.
British Journal of Clinical Pharmacology
|January 1, 1992
Summary
Concurrent use of common over-the-counter metal ions like iron, zinc, aluminum, and magnesium significantly reduces norfloxacin excretion. This interaction may compromise the antibiotic
Area of Science:
- Pharmacology
- Drug Interactions
- Clinical Pharmacy
Background:
- Norfloxacin is a widely used fluoroquinolone antibiotic.
- Over-the-counter (OTC) medications containing metal ions are frequently used.
- Potential interactions between norfloxacin and OTC drugs are not fully understood.
Purpose of the Study:
- To investigate the effect of common OTC metal ions on norfloxacin's urinary excretion.
- To determine the in vitro interaction between norfloxacin and specific metal ions.
Main Methods:
- Eight healthy volunteers received norfloxacin with various OTC preparations containing metal ions (iron, zinc, aluminum, magnesium, bismuth).
- Urinary excretion of norfloxacin was measured over 24 hours.
- In vitro complex formation between norfloxacin and metal ions was assessed.
Main Results:
- Ferrous sulfate, zinc sulfate, aluminum hydroxide, and magnesium hydroxide significantly reduced 24-hour norfloxacin urinary excretion by 50-90%.
- Bismuth subsalicylate showed no significant effect on norfloxacin excretion.
- In vitro studies confirmed complex formation between norfloxacin and iron, zinc, aluminum, and magnesium ions.
Conclusions:
- Commonly used OTC metal ions can significantly decrease norfloxacin's urinary excretion.
- The formation of metal-norfloxacin complexes is the likely mechanism for reduced drug excretion.
- Concomitant administration of norfloxacin with these OTC preparations may compromise its therapeutic efficacy.