Effects of aluminum hydroxide and calcium carbonate antacids on the bioavailability of ciprofloxacin

Antimicrob Agents Chemother. 1992 Apr;36(4):830-2. doi: 10.1128/AAC.36.4.830.


This study was designed to determine the effects of an aluminum hydroxide antacid and a calcium carbonate antacid on the bioavailability of ciprofloxacin (Cipro). Cipro (750 mg) was administered orally to 12 healthy volunteers in a three-way randomized crossover design. The three treatments included Cipro alone, four 850-mg calcium carbonate tablets taken 5 min before Cipro, and three 600-mg aluminum hydroxide tablets taken 5 min before Cipro. The relative bioavailability of Cipro when given with calcium carbonate was approximately 60% of the control value. When Cipro was given with aluminum hydroxide, the relative bioavailability was approximately 15%. Urinary recovery of Cipro in the aluminum hydroxide treatment group was approximately one-fourth of that in the calcium carbonate group. Although calcium carbonate decreased absorption to a lesser extent than aluminum hydroxide, these data suggest that antacids containing either aluminum or calcium should not be given concomitantly with Cipro.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aluminum Hydroxide / administration & dosage
  • Aluminum Hydroxide / pharmacology*
  • Biological Availability
  • Calcium Carbonate / administration & dosage
  • Calcium Carbonate / pharmacology*
  • Ciprofloxacin / administration & dosage
  • Ciprofloxacin / pharmacokinetics*
  • Humans
  • Male


  • Ciprofloxacin
  • Aluminum Hydroxide
  • Calcium Carbonate