CLINICAL AND CHEMICAL INTERACTIONS BETWEEN IRON PREPARATIONS AND CIPROFLOXACIN

1 The effect of ferrous sulphate (300 mg), ferrous gluconate (600 mg), and a combination tablet of iron (10 mg), magnesium (100 mg), zinc (15 mg), calcium (162 mg), copper (2 mg), and manganese (5 mg) (Centrum Forte) co-administration on ciprofloxacin bioavailability was tested in eight healthy subjects. 2 Peak serum ciprofloxacin concentrations and area under the curve (AUC) were significantly reduced when ciprofloxacin was administered with 300 mg ferrous sulphate (3.0 vs 2.0 mg l-1, P < 0.05 and 12.3 vs 6.7 mg l-1 h, P < 0.01, respectively). Reductions in peak ciprofloxacin concentrations and AUC also occurred when ciprofloxacin was ingested with 600 mg ferrous gluconate (1.3 mg l-1, P < 0.01 and 4.1 mg l-1 h, P < 0.01, respectively) and a Centrum Forte tablet (1.4 mg l-1, P < 0.01 and 5.4 mg l-1 h, P < 0.01, respectively). 3 When ferrous ion was mixed with ciprofloxacin, rapid spectral changes occurred (t1/2 = 1.9 min). Additional studies were consistent with oxidation of the ferrous form of iron to its ferric form, which is followed by rapid formation of a Fe3+ -ciprofloxacin complex. Ciprofloxacin seems to bind to ferric ion in a ratio of 3:1 by interacting with the 4-keto and 3-carboxyl groups on ciprofloxacin. 4 The formation of a ferric ion-ciprofloxacin complex is probably the cause of the reduction in ciprofloxacin bioavailability in the presence of iron.