Aluminum, magnesium or iron reduces absorption of Ciprofloxacin. It also decreases the clearance of theophylline, increases blood concentrations of midazolam according to some isolated reports. The urinary excretion of Ciprofloxacin reduced by probenecid. When used simultaneously with azlocillin, it has resulted in higher and more prolonged concentration of Ciprofloxacin. Changes in pharmacokinetics of fluoroquinolones such as Ciprofloxacin have been reported when given with histamine H2 antagonist, possibly due to the change in gastric pH, but do not seem to be of much of clinical significance.
Theophylline interferes with metabolism of caffeine, enhances effects of oral anticoagulants warfarin, glibenclamide, probenecid, metoclopramide and its derivatives.